do you experiment on animals

Why Do Scientists Experiment on Animals?

Animal studies in science are experiments that control an animal's behaviour or physiology for study, often to serve as a model for human biology where testing on humans is impractical or unethical.

The species or classification of animals used in testing largely depends on the goal of the experiment.

For example, zebrafish are quick to breed, easy to house, and transparent as embryos - but they also carry 70 percent of the genes found in humans. All this makes them suitable for studies on human disease and embryological development.

Rodents have a long history of being used for science experiments, and today make up around three quarters of all animal subjects in testing. Easy to raise and breed, their mammalian physiology and genomes overlap even more considerably with those of humans, making them suitable models for studying behaviours, toxicology, and the effects of medical treatments.

Non-human primates , especially chimpanzees and rhesus monkeys, have also been used extensively in scientific testing. While harder to reproduce in large numbers and challenging to house comfortably, experiments on our closest evolutionary relatives can yield valuable information on a wide range of issues, from drug toxicity to neurology.

However, the close likeness of non-human primates to ourselves also means their use in experiments is the most controversial of all types of animal testing . Generally, data across different countries, including the European Union , show that non-human primate research constitutes less than 1 percent of all animal studies.

However, studies on monkeys aren't yet phased out: In 2017, the US had a record-high number of studies involving monkeys.

How useful are animal models in experiments?

If conducted under strict methods with appropriate protocols, animal experimentation can provide reliable evidence on how that animal's physiology or behaviour responds under the experiment's conditions; genetic studies are particularly effective, while behavioural studies can yield less firm conclusions.

Unfortunately, the nature of experiments that make use of animal models can often lend themselves to being poorly designed, conducted, or analysed. There can also be a sex imbalance, with much of rodent research done only on male mice , for example.

Experiments that apply the findings to human biology require significant assumptions on whether any differences between them are significant. Even where animals are genetically altered to better reflect human biochemistry, there is always the risk that an unidentified behaviour or function might mean the experimental results can't be applied to humans.

This doesn't make animal models useless. As with all experiments, the weight of replicated experiments performed critically under peer review determines how confident we should be in a set of results.

It does mean we ought to be cautious about how results from an experiment based on an animal model might apply to our own bodies.

What are the ethics of testing on animals?

Concerns surrounding experiments using animal models are often based on the morality of depriving animals of their liberty or subjecting them to pain or discomfort, to meet a human need or value.

At an extreme end of the ethics spectrum is the claim that all animals have rights equal to humans, and therefore any experiment that wouldn't ethically be conducted on humans shouldn't be conducted on any animal.

Ethics boards today tend to weigh up the potential benefits of an experiment with the risks of harm and suffering to the animal. However, what constitutes a benefit , as well as objective ways to define acceptable limits of harm, pain, and discomfort in different animals can make this more challenging than first appears.

What is the future of animal testing?

More than half a century ago, zoologists William Russell and Rex Burch suggested experimentation should become more humane by following the three Rs; restrict when to use animals; refine the kinds of experiments conducted on them; and replace as the technology becomes available.

Advances in computer modelling and in-vitro tissue culture design are continuing to provide alternatives to animal models that don't suffer from the same ethical and practical limitations.

Human tissue models, such as those making up 3D tissue conglomerates called organoids , are increasingly serving as appropriate models for studying growth and development.

These solutions might not make the way we conduct the experiments themselves more trustworthy. But with robust debate and reliable review procedures, they will steadily make animal testing - and the ethical and practical problems they bring - a thing of the past.

All Explainers are determined by fact checkers to be correct and relevant at the time of publishing. Text and images may be altered, removed, or added to as an editorial decision to keep information current.

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• Future Perfect

Animal testing, explained

Is anything really “cruelty-free”?

by Celia Ford

It’s nearly impossible to go a day without benefitting from the suffering of animals. The ingredients in your toiletries and makeup; your medicine, vaccines, and implants; your cleaning supplies; the chemicals that helped grow your food — most of it was, at some point, tested on animals.

For centuries, the biological sciences have relied on animal testing. To figure out how a machine works, you need to disassemble it and check out its component parts. Understanding the living body, one of nature’s most complex and beautiful machines, is no different. Taking apart and fiddling with a toaster doesn’t hurt anyone, but dismantling a biological system certainly does.

Many scientists believe that experimenting on living animals is a necessary means of solving problems that affect both humans and animals. But these experiments often involve animals experiencing distress, whether from the side effects of an experimental drug, an intentionally inflicted illness, or simply their confined living situation. Some lucky lab animals get to spend their retirement in sanctuaries once they’re no longer needed. Most of the time, the animal dies, either as a direct consequence of the experiment or from euthanasia.

More often than not, animal research happens behind closed, locked, unmarked doors. That lack of transparency makes it difficult to know what to think about animal testing, and public opinion is tellingly divided. A 2018 Pew Research Center survey found that 47 percent of people in the US support the use of animals in scientific research, and 52 percent oppose it. Unlike climate change or reproductive health , where the parties are highly polarized, animal testing is one of few science-related policy issues where the attitudes of Republicans and Democrats are pretty similar: Both parties are split roughly 50-50.

Experimenting on animals places two seemingly good things — medical innovation and animal welfare — at odds. Even those who support animal research generally hold nuanced, conflicted beliefs about it, and questions about the nature and extent of animal testing are still hotly debated.

Inside this story

• What animal testing actually does
• Who is looking out for the welfare of animals
• The truth behind labels like “cruelty-free”
• The future of animal-free testing

Brands frequently mislead consumers about animal testing involving their products with vague labeling, and alternative research methods aren’t as broadly applicable as some activist organizations imply . Meanwhile, research facilities often ban employees from sharing photos of lab animals without institutional approval and rarely let the media observe experiments for themselves.

After spending six years as a neuroscience PhD student working in a lab with monkeys, I left academia with the impression that animal testing is neither as well-managed or justified as regulators claim, nor as malicious as others fear. Government agencies are starting to direct funding toward finding alternatives to animal testing, but the use of animals is deeply embedded in biological sciences.

A world without lab animals may be possible, but we don’t live in it yet. Here’s what’s actually going on.

What is animal testing?

Before humans invented microscopes, universities, or even paper, we were using animals for medical research. Over two millennia ago , ancient Greek philosopher Aristotle dissected dozens of animal species to better understand their anatomy and argued that studying their bodies could teach us a lot about our own biology. Over four centuries later, Galen of Pergamon , one of the most pivotal characters in Western medical history, performed public surgeries on animals ( especially monkeys ) for science, providing a spectacle that attracted curious audiences.

Today, animal experimentation is widespread and conducted far from the public eye. It falls under two broad, semi-overlapping umbrellas: biomedical research (which aims to understand, prevent, and treat diseases, as well as uncover fundamental information about how bodies work) and toxicology , or testing the effects of chemicals (including everything from toothpaste and makeup to pesticides) on living things.

Humans generally don’t want to be proverbial guinea pigs for new medicines or consumer products. We’d rather know that things are safe before we put them anywhere near our bodies. Companies, whether they deal in cosmetics or pharmaceuticals, also don’t want to be liable for poisoning their customers.

People can participate in experiments that might harm them, but historically, at best, such projects have been difficult to administer . At worst, they have involved illegal human experimentation that cast a long, dark shadow over the field of medical research.

The Tuskegee syphilis study , for example, put hundreds of poor Black men with untreated syphilis through decades of invasive tests in exchange for hot meals and basic medical treatment, just to see how the disease would progress if left untreated. Effective treatments became available during the study, but researchers withheld them. Once the experiment’s scandalous history was publicly disclosed in 1972 , the US government formalized basic ethical guidelines for human research and required Institutional Review Boards (IRBs) to approve studies on humans.

Today, many questions — like What is the lethal dose of this new drug? and Does this new surgical technique actually work? — can’t ethically be asked regarding humans without first being tested on a nonhuman subject.

For a long time, animals were the only alternative to humans available. To figure out the lethal dose of a new drug, scientists can give increasingly large amounts of it to mice and see what it takes to kill them. To test whether a brain implant actually relieves Parkinson’s symptoms, scientists do brain surgery on monkeys . Without computational models or cell cultures sophisticated enough to mimic the complicated interactions between organs, the options have historically been to use animals as a proxy or to drop or scale back your planned research.

We can only guess how many animals are being used in scientific experiments worldwide. The United States Department of Agriculture (USDA) publishes official reports on animal research every year, but they only include animals protected by the Animal Welfare Act (AWA), the federal law setting basic standards for the treatment and housing of certain farm animals and lab animals. The law covers dogs, cats, monkeys, guinea pigs, hamsters, pigs, rabbits, and sheep. In 2019, about 800,000 animals protected by AWA were used in research — 930,000, if you add those that lived in labs but were never included in a study.

Notably, the AWA doesn’t apply to mice and rats, which several studies estimate account for somewhere between 93 and 99 percent of all lab animals in the US. The AWA also excludes invertebrates like flies, worms, fish, and cephalopods like octopuses, whose intelligence makes them intriguing neuroscience subjects. The EU, which counts all vertebrates used in experiments, tallied about 10.6 million animals used in 2017. It’s harder to pin down a number in the US. Depending on who you ask , there might be 10 million rodents subjected to scientific experiments annually, or there might be 111 million. (Either way, it’s more than three times the number of rats in New York City.)

Rodents make appealing animal models for many scientists because they’re smart enough to learn simple tasks but are still socially regarded as pests; those who kill rats for a living don’t face the same kind of backlash as someone who, say, boasts about shooting a puppy . Nearly all mouse genes share functions with human genes, so at a basic level, their biology resembles ours. Mice only live for a year or two, enabling scientists to study things like chronic disease progression without waiting an entire human lifespan. And scientists can genetically alter mice in countless ways, knocking out or adding DNA to express diseases or make certain cell types glow under a microscope.

In some cases, a research question requires invasively studying a full, living biological system, but the gap between mice and humans is too wide. The USDA reported that 68,257 monkeys were used in 2019 to study subjects like SARS-CoV-2 , Parkinson’s disease , and HIV , where physiological and cognitive similarity to humans was a priority. Those primates were mostly macaques and marmosets; the use of chimpanzees (our closest ape relative) is now banned in many countries , including the US .

But monkey research may not be viable much longer. While hundreds of monkey experiments are being funded by the NIH , there aren’t enough long-tailed macaques to go around. In a desperate attempt to keep up with skyrocketing demand, thousands of wild-caught monkeys are illegally imported to US research institutions from countries like Cambodia. Two years ago, the long-tailed macaque was listed as endangered for the first time. PETA petitioned the US government to protect the species under the Endangered Species Act , which could end their use in research altogether, but the request has yet to be approved. Most people are uncomfortable with the idea of experimenting on an animal so similar to us, including some of the scientists who do it. However, many scientists and policymakers agree that we still don’t have non-animal alternatives that can answer tough research questions involving interactions between organs. Researchers worry that the looming primate shortage in the US — engendered by transportation restrictions and therapeutic testing requirements and exacerbated by pandemic-era demands — will limit our ability to respond to public health emergencies.

Monkeys are traditionally recognized as the only nonhuman animals that react to drugs with human-specific targets, meaning that in some cases, their body’s reactions could uniquely predict whether a drug will be safe and effective for humans. During the first years of the Covid-19 pandemic, monkeys were considered so crucial to SARS-CoV-2 research that when the rhesus macaque supply dried up, scientists didn’t turn to cell cultures or computer models — they just looked for different monkeys .

You might not agree that this research justifies the nonconsensual use of highly intelligent animals; many don’t, for both ethical and scientific reasons. But it’s happening, and if you’ve been vaccinated or take medications, you’ve likely benefited from it.

Who’s looking out for the welfare of lab animals?

The regulatory framework surrounding animal research is a tangled web of acronyms, committees, and working groups. Since the Animal Welfare Act was passed in 1966, the USDA has been in charge of enforcing it through inspections and annual reports.

In theory, researchers have to justify the use of animals in their work. To conduct an animal experiment, scientists in the US go through a review process with their Institutional Animal Care and Use Committee (IACUC), which decides whether animals are “necessary” and whether steps are being taken to minimize their pain.

IACUCs are mostly comprised of researchers who experiment on animals and the veterinarians who help them, strongly biasing committees toward approving animal experiments. In the US and elsewhere, scientists are subtly incentivized to use animals, even when they aren’t actually necessary. Academic journals tend to preferentially publish work with animal methods , and academic careers hinge on accumulating publications . These norms seep into the labs where animal experiments are performed. New animal researchers often receive explicit instructions on how to steer clear of animal rights activists, according to several researchers I spoke with while working as a neuroscientist (as well as my own experience).

This can make holding institutions accountable for animal welfare violations challenging. While researchers are required to report information about animals in their facilities, like what medical procedures they’ve received and when they’ve been fed, they are told to keep these reports “ minimal, but complete .” In other words: Avoid including photos, videos, or graphic descriptions that could enrage activists or entice the media.

There also isn’t a clear legal definition for “animal cruelty” in research settings beyond violations of the basic standards outlined by the Animal Welfare Act. This leaves some room for interpretation about what is acceptable and what would constitute illegal treatment. The EU’s Directive 2010/63/EU , its equivalent of the Animal Welfare Act, emphasizes that animals should only be used if there are no other options and if the potential benefits of the research outweigh the animals’ suffering.

This cost-benefit analysis is subjective. For example, a team of immunologists studying cancer in mice would probably say that the potential public health benefits of their work justify harming mice. A team of science policy experts at PETA would say that mice aren’t ours to use and that these experiments often don’t translate to human trials, anyway .

To bridge this ethical divide, research universities and private companies in the UK have signed a Concordat on Openness on Animal Research , pledging to proactively and transparently inform the public about their treatment of lab animals. In the decade since its launch, nine other countries have followed suit. It’s likely not a coincidence that these countries generally have the tightest restrictions on animal use. However, an independent review found that Concordat signatories in the UK are still struggling to be transparent about their animal research practices in the face of potential disapproval.

On top of the slow pace for necessary regulation, stigma obscures the true nature of what happens in these labs. In the late 2000s, the most extreme opponents of animal testing used violence to try to end the practice, sending poisoned razors and death threats to lab heads and, in at least one case, firebombing a neurobiologist’s car . But rather than encourage scientists to reconsider their methods, attacks like these cemented a culture of silence. While physical violence is not representative of activism against animal testing today — which usually centers around investigations , government advocacy , and direct care for animals and has shifted to become more inclusive — the threat of retaliation still haunts animal researchers , some of whom are encouraged by their institutions to hide their connections to animal testing from the public.

Scientists “don’t want to feel like they’re bad people,” said neuroscientist and author Garet Lahvis, who has written about primate research for Vox.

What if I want to avoid animal testing altogether? What does “cruelty-free” mean?

After learning about what lab animals go through, some people will want to find ways to avoid the products of animal testing. This is much easier said than done, however.

Animal testing is pervasive in health care. Many treatments we take for granted today, like anesthesia , flu shots , and allergy medications , went through preclinical trials in animals before reaching us. They are also valuable to your health, so please keep taking your medicine if you need it. We have more power to avoid animal testing elsewhere. Animal testing requirements are generally looser to nonexistent for cosmetics, cleaning supplies, and other household chemicals, so it’s possible to buy “cruelty-free” makeup or laundry detergent.

The legal distinction between “cosmetics” and “drugs” is blurry, though. Essentially, drugs claim to affect the body’s structure or function in some way, while cosmetics are things you apply to your body to change your appearance (like lipstick) or clean yourself (like deodorant — but not soap, which is neither a cosmetic nor a drug, but its own special category ). Many products we might think of as cosmetics are, in fact, also drugs, like anti-dandruff shampoo, tinted moisturizer with sunscreen, and other cosmetics that claim to treat some ailment. In the US, all of these items had to be tested on animals until the FDA Modernization Act 2.0 took effect in 2023 .

Cruelty-free claims used on product labels are often misleading, and differences in regulation across countries add to the confusion.

For years, the EU , Canada, Mexico, and 16 other countries (including South Korea, for the skincare girlies ) have had legislation in place banning animal testing for cosmetics or their ingredients (although last year, the UK changed their policy to allow testing for makeup ingredients again). But testing on final products or their ingredients has never been banned in the US. Even if a company doesn’t test its final product on animals, it may still run animal tests on raw ingredients. And even if those raw ingredients aren’t currently being tested on animals, they probably were when they were first introduced.

The US government doesn’t have a legal definition for the terms “cruelty-free” or “not tested on animals.” A product labeled “cruelty-free” likely earned voluntary certification from a private organization like Leaping Bunny or PETA’s Beauty Without Bunnies program by pledging to end animal testing at all stages of product development. The definition of “cruelty-free” isn’t standardized across animal protection groups, but earning a “bunny label” generally means that a brand attested to never conducting tests on animals during a product’s development.

Despite pressure from advocates and consumers, many US companies don’t bother with these pledges on animal testing. As of this year, approximately 310 brands globally still test their beauty and household cleaning products on animals. And some actively say they don’t test on animals at all but still sell their products to countries like China, which, until recently, required that all cosmetics (even imported ones) be tested on animals . Most certification programs exclude brands and products sold in China for this very reason.

To make it easier for US companies to sell truly cruelty-free products in China, US regulators and animal welfare advocates have been lobbying their Chinese counterparts for years to change their approach to animal testing for consumer products. Twenty years ago, Thomas Hartung, a toxicologist at the Johns Hopkins Center for Alternatives to Animal Testing, spoke with the National Medical Products Administration (China’s FDA) about regulating animal testing of chemicals and told me “it was like we were coming from Mars.”

In response to yearslong campaigns by organizations like PETA and the Institute for In Vitro Sciences, China recently lifted this requirement . It is now possible to buy Chinese cosmetics that weren’t tested on animals — kind of.

As of January 2021, China no longer requires pre-market or post-market animal testing for cosmetics, meaning that companies from the US and elsewhere can sell things like eyeliner or nail polish in China while still maintaining “cruelty-free” status. But certain “special cosmetics,” like sunscreen, teeth whiteners, and hair dye, or products made for children, are all still required to undergo animal testing. And if a product uses a raw ingredient that isn’t already approved in China, foreign companies have to either reformulate or get that ingredient approved, which requires more animal testing. So, it’s possible to sell US-made “cruelty-free” products in China, but it requires sifting through a confusing and ever-evolving swamp of documentation requirements.

We have made imperfect progress toward a world of cruelty-free cosmetics. While the number of animals used for cosmetic testing in the US has dropped by 90 percent since the 1980s, 44 of the largest 50 cosmetic brands in the world still are not cruelty-free . And without a consensus agreement on what “cruelty-free” actually means, consumers are left to guess which bunny labels are genuine and which are false advertising.

Since many brands can just slap on cruelty-free claims while still sending products abroad to animal testing labs, for now, if you want to avoid animal testing, Leaping Bunny and Beauty Without Bunnies are your best bets. These certifications consider post-market animal testing in other countries as part of their standards.

Alternative methods are (slowly) coming

In some places, like the UK, strict restrictions on animal research and a commitment to transparency have considerably improved lab conditions in recent decades. Companies like Neuralink , however, continue to perform high-risk, ethically dubious experiments hidden from the public eye.

While new alternative methods are under development, animal testing remains necessary in at least some circumstances. Tight regulation — and buy-in from scientists — will be key to minimizing harm in the meantime.

Nicole Kleinstreuer, acting director of the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) , told me that improving the current state of animal testing hinges on researchers gathering “the courage to admit that we can substantially improve upon how we’ve been doing things historically.”

Until relatively recently, alternatives to animal testing in many areas of science were very limited. But in the past decade, bioengineering and computer science have advanced rapidly. New tools like AI, organoids (balls of stem cells that grow into organ tissue), and CRISPR have made replacing animals, at least in certain experiments, more attainable.

For chemical testing, good animal-free research methods have been around for decades — long before most scientists considered using them. Even when well-validated animal alternatives exist, researchers can be slow to adopt them . Hartung, a toxicologist, said, “I turned 60 last year. The methods they’re using were introduced when I was in kindergarten.”

In 2007, the National Academies of Sciences, Engineering, and Medicine , a nonprofit that produces independent policy guidance for the US, laid out a strategy for researchers to move away from using animals in toxicity testing and to develop faster, more human-relevant models to take their place. Today, a number of working groups, both within the US and collaborating internationally, are still trying to put this principle into practice.

As the largest single public funder of biomedical research in the world, the National Institutes of Health (NIH) is uniquely positioned to influence animal testing. In 2023, the NIH spent an estimated $19 billion on US-based projects involving animals, according to Citizens for Alternatives to Animal Research and Experimentation. Between 2011 and 2021, they spent $2.2 billion on projects based in other countries — where oversight boils down to trusting self-generated, non-validated reports from foreign institutions.

Kleinstreuer said that changing the current state of animal research “really necessitates a sea change, and a dramatic investment on the part of funders, particularly the NIH.”

The people in charge of the money have the power to redistribute it and could choose to spend more of it on projects that don’t use animals and less on those that do. That’s the easy part. “It’s kind of the lowest-hanging fruit, and the easiest ask,” said Emily Trunnell , director of Science Advancement and Outreach at PETA. “Even people who are in support of animal testing are on board with the funding of different methods as well.”

NICEATM, led by Kleinstreuer, is doing the in-the-weeds work of figuring out how we’d know whether a replacement method is good enough to substitute for animal experiments. Earlier this year, the NIH also approved the Complement Animal Research in Experimentation (Complement-ARIE) Program , which will set up technology development centers for researchers to make better human-based models.

Non-animal methods can already outperform certain animal tests. Back in 2018, Hartung’s research group created algorithms mapping the relationships between 10,000 known chemical compounds. With this model and lots of data, they predicted the toxicity of 89 percent of the 48,000 toxic chemicals more accurately than animal tests could and for much less money — without endangering any living creatures. Since then, Hartung said things have only become better. But AI-driven research methods are still limited by what real-world data has already been collected. “When you have no data,” he said, “nothing is possible.”

In some cases, using animals is simply bad science. There are some questions “that absolutely necessitate a human cell-based approach,” Kleinstreuer said. “You can’t look at the efficacy of a drug whose target is not expressed in animals by using animal models,” she added. Certain cancer drugs target protein receptors that only exist in humans, and gene therapies often aim to rewrite human-specific DNA sequences. One emerging option: take a sample of human cells, reprogram them to behave like whatever cells you want them to be, and test your drug on the resulting tissue sample.

These tools offer exciting opportunities to personalize medicine to individual patients, but it’s still tough to extrapolate results from a small mass of lab-grown cells in a tightly controlled environment to a human body and the complex interactions of its organ systems. Cancer and embryonic development are incredibly complex biological processes, involving lots of different interconnected body parts that evolve over time. Without that capability, Kleinstreuer said it’s harder to argue that a substance is actually safe and ready to clear for human use.

Change happens one retirement at a time

As it stands, alternatives to animal tests are not being used as widely as they should be, especially in cosmetics. But if we want to study things like deep brain stimulation or run safety tests on new cancer drugs , animal tests are all we have.

While we are stuck with animal experiments, we can try to limit them and make them more humane. Lahvis believes that we should have extremely strict criteria for what animal experiments are funded. Strategically allocating grant funding could not only save millions of lives, but also inspire better science.

Convincing animal researchers to replace animals with other methods is still a huge challenge. Hartung joked that in academia, change happens “one retirement at a time.” Unfortunately, “it’s often been one graveyard at a time,” as retired scientists continue to serve as reviewers who help choose what new projects get funded and published.

The further along a scientist is in their career, the more challenging it becomes to pivot. Because scientists are pushed to maintain a constant level of productivity, Trunnell said, someone who builds their whole lab around their current use of animal models has no incentive to change, unless they have a strong desire to do so. Changing tactics could mean putting their job on the line.

“We’re highly leveraged by the system to keep doing what we’ve always done,” Lahvis agreed. And, Hartung said, turning against a tried-and-true method would require a scientist invalidating their existing body of work or at least acknowledging that it was either unethical, ineffective, or inefficient. Using past observations to inform future experiments is at the core of the scientific method, but, Hartung said, “We’re not trained to be very self-critical.”

That said, a growing number of scientists support the development of non-animal methods, even as they continue to work with animals themselves. People want new tools, whether for the sake of animal welfare or simply because it would make for better science. We might just have to wait another generation.

• Animal Welfare

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Should Animals Be Used for Scientific or Commercial Testing?

• History of Animal Testing

Animals are used to develop medical treatments, determine the toxicity of medications, check the safety of products destined for human use, and other  biomedical , commercial, and health care uses. Research on living animals has been practiced since at least 500 BC.

Descriptions of the dissection of live animals have been found in ancient Greek writings from as early as circa 500 BC. Physician-scientists such as  Aristotle ,  Herophilus , and  Erasistratus  performed the experiments to discover the functions of living organisms.  Vivisection  (dissection of a living organism) was practiced on human criminals in ancient Rome and Alexandria, but prohibitions against mutilation of the human body in ancient Greece led to a reliance on animal subjects. Aristotle believed that animals lacked intelligence, and so the notions of justice and injustice did not apply to them.  Theophrastus , a successor to Aristotle, disagreed, objecting to the vivisection of animals on the grounds that, like humans, they can feel pain, and causing pain to animals was an affront to the gods. Read more background…

Pro & Con Arguments

Pro 1 Animal testing contributes to life-saving cures and treatments for humans and animals alike. Nearly every medical breakthrough in the last 100 years has resulted directly from research using animals, according to the California Biomedical Research Association. To name just a few examples, animal research has contributed to major advances in treating conditions including breast cancer, brain injury, childhood leukemia, cystic fibrosis, multiple sclerosis, and tuberculosis. Testing on animals was also instrumental in the development of pacemakers, cardiac valve substitutes, and anesthetics. [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] Scientists racing to develop a vaccine for coronavirus during the 2020 global pandemic needed to test on genetically modified mice to ensure that the vaccine did not make the virus worse. Nikolai Petrovsky, professor in the College of Medicine and Public Health at Flinders University in Australia, said testing a coronavirus vaccine on animals is “absolutely essential” and skipping that step would be “fraught with difficulty and danger.” [ 119 ] [ 133 ] Researchers have to test extensively to prevent “vaccine enhancement,” a situation in which a vaccine actually makes the disease worse in some people. “The way you reduce that risk is first you show it does not occur in laboratory animals,” explains Peter Hotez, Dean for the National School of Tropical Medicine at Baylor College. [ 119 ] [ 141 ] Further, animals themselves benefit from the results of animal testing. Vaccines tested on animals have saved millions of animals that would otherwise have died from rabies, distemper, feline leukemia, infectious hepatitis virus, tetanus, anthrax, and canine parvo virus. Treatments for animals developed using animal testing also include pacemakers for heart disease and remedies for glaucoma and hip dysplasia. [ 9 ] [ 21 ] Animal testing has also been instrumental in saving endangered species from extinction, including the black-footed ferret, the California condor and the tamarins of Brazil. The American Veterinary Medical Association (AVMA) endorses animal testing to develop safe drugs, vaccines, and medical devices. [ 9 ] [ 13 ] [ 23 ] Read More

Pro 2 Animals are appropriate research subjects because they are similar to human beings in many ways. Chimpanzees share 99% of their DNA with humans, and mice are 98% genetically similar to humans. All mammals, including humans, are descended from common ancestors, and all have the same set of organs (heart, kidneys, lungs, etc.) that function in essentially the same way with the help of a bloodstream and central nervous system. Because animals and humans are so biologically similar, they are susceptible to many of the same conditions and illnesses, including heart disease, cancer, and diabetes. [ 9 ] [ 17 ] [ 18 ] Animals often make better research subjects than humans because of their shorter life cycles. Laboratory mice, for example, live for only two to three years, so researchers can study the effects of treatments or genetic manipulation over a whole lifespan, or across several generations, which would be infeasible using human subjects. Mice and rats are particularly well-suited to long-term cancer research, partly because of their short lifespans. [ 9 ] [ 29 ] [ 30 ] Further, animals must be used in cases when ethical considerations prevent the use of human subjects. When testing medicines for potential toxicity, the lives of human volunteers should not be put in danger unnecessarily. It would be unethical to perform invasive experimental procedures on human beings before the methods have been tested on animals, and some experiments involve genetic manipulation that would be unacceptable to impose on human subjects before animal testing. The World Medical Association Declaration of Helsinki states that human trials should be preceded by tests on animals. [ 19 ] [ 20 ] A poll of 3,748 scientists by the Pew Research Center found that 89% favored the use of animals in scientific research. The American Cancer Society, American Physiological Society, National Association for Biomedical Research, American Heart Association, and the Society of Toxicology all advocate the use of animals in scientific research. [ 36 ] [ 37 ] [ 38 ] [ 39 ] [ 40 ] [ 120 ] Read More

Pro 3 Animal research is highly regulated, with laws in place to protect animals from mistreatment. In addition to local and state laws and guidelines, animal research has been regulated by the federal Animal Welfare Act (AWA) since 1966. As well as stipulating minimum housing standards for research animals (enclosure size, temperature, access to clean food and water, and others), the AWA also requires regular inspections by veterinarians. [ 3 ] All proposals to use animals for research must be approved by an Institutional Animal Care and Use Committee (IACUC) set up by each research facility. Most major research institutions’ programs are voluntarily reviewed for humane practices by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC). [ 24 ] [ 25 ] Animal researchers treat animals humanely, both for the animals’ sake and to ensure reliable test results. Research animals are cared for by veterinarians, husbandry specialists, and animal health technicians to ensure their well-being and more accurate findings. Rachel Rubino, attending veterinarian and director of the animal facility at Cold Springs Harbor Laboratory, says, “Most people who work with research animals love those animals…. We want to give them the best lives possible, treat them humanely.” At Cedars-Sinai Medical Center’s animal research facility, dogs are given exercise breaks twice daily to socialize with their caretakers and other dogs, and a “toy rotation program” provides opportunities for play. [ 28 ] [ 32 ] Read More

Con 1 Animal testing is cruel and inhumane. Animals used in experiments are commonly subjected to force feeding, food and water deprivation, the infliction of burns and other wounds to study the healing process, the infliction of pain to study its effects and remedies, and “killing by carbon dioxide asphyxiation, neck-breaking, decapitation, or other means,” according to Humane Society International. The US Department of Agriculture reported in Jan. 2020 that research facilities used over 300,000 animals in activities involving pain in just one year. [ 47 ] [ 102 ] Plus, most experiments involving animals are flawed, wasting the lives of the animal subjects. A peer-reviewed study found serious flaws in the majority of publicly funded US and UK animal studies using rodents and primates: “only 59% of the studies stated the hypothesis or objective of the study and the number and characteristics of the animals used.” A 2017 study found further flaws in animal studies, including “incorrect data interpretation, unforeseen technical issues, incorrectly constituted (or absent) control groups, selective data reporting, inadequate or varying software systems, and blatant fraud.” [ 64 ] [ 128 ] Only 5% of animals used in experiments are protected by US law. The Animal Welfare Act (AWA) does not apply to rats, mice, fish, and birds, which account for 95% of the animals used in research. The types of animals covered by the AWA account for fewer than one million animals used in research facilities each year, which leaves around 25 million other animals without protection from mistreatment. The US Department of Agriculture, which inspects facilities for AWA compliance, compiles annual statistics on animal testing but they only include data on the small percentage of animals subject to the Act. [ 1 ] [ 2 ] [ 26 ] [ 28 ] [ 135 ] Even the animals protected by the AWA are mistreated. Violations of the Animal Welfare Act at the federally funded New Iberia Research Center (NIRC) in Louisiana included maltreatment of primates who were suffering such severe psychological stress that they engaged in self-mutilation, infant primates awake and alert during painful experiments, and chimpanzees being intimidated and shot with a dart gun. [ 68 ] Read More

Con 2 Animal tests do not reliably predict results in human beings. 94% of drugs that pass animal tests fail in human clinical trials. Over 100 stroke drugs and over 85 HIV vaccines failed in humans after succeeding in animal trials. Nearly 150 clinical trials (human tests) of treatments to reduce inflammation in critically ill patients have been undertaken, and all of them failed, despite being successful in animal tests. [ 57 ] [ 58 ] [ 59 ] Drugs that pass animal tests are not necessarily safe. The 1950s sleeping pill thalidomide, which caused 10,000 babies to be born with severe deformities, was tested on animals prior to its commercial release. Later tests on pregnant mice, rats, guinea pigs, cats, and hamsters did not result in birth defects unless the drug was administered at extremely high doses. Animal tests on the arthritis drug Vioxx showed that it had a protective effect on the hearts of mice, yet the drug went on to cause more than 27,000 heart attacks and sudden cardiac deaths before being pulled from the market. [ 5 ] [ 55 ] [ 56 ] [ 109 ] [ 110 ] Plus, animal tests may mislead researchers into ignoring potential cures and treatments. Some chemicals that are ineffective on (or harmful to) animals prove valuable when used by humans. Aspirin, for example, is dangerous for some animal species. Intravenous vitamin C has shown to be effective in treating sepsis in humans, but makes no difference to mice. Fk-506 (tacrolimus), used to lower the risk of organ transplant rejection, was “almost shelved” because of animal test results, according to neurologist Aysha Akhtar. A report on Slate.com stated that a “source of human suffering may be the dozens of promising drugs that get shelved when they cause problems in animals that may not be relevant for humans.” [ 105 ] [ 106 ] [ 127 ] Read More

Con 3 Alternative testing methods now exist that can replace the need for animals. Other research methods such as in vitro testing (tests done on human cells or tissue in a petri dish) offer opportunities to reduce or replace animal testing. Technological advancements in 3D printing allow the possibility for tissue bioprinting: a French company is working to bioprint a liver that can test the toxicity of a drug. Artificial human skin, such as the commercially available products EpiDerm and ThinCert, can be made from sheets of human skin cells grown in test tubes or plastic wells and may produce more useful results than testing chemicals on animal skin. [ 15 ] [ 16 ] [ 50 ] [ 51 ] Michael Bachelor, Senior Scientist and Product Manager at biotech company MatTek, stated, “We can now create a model from human skin cells — keratinocytes — and produce normal skin or even a model that mimics a skin disease like psoriasis. Or we can use human pigment-producing cells — melanocytes — to create a pigmented skin model that is similar to human skin from different ethnicities. You can’t do that on a mouse or a rabbit.” The Environmental Protection Agency is so confident in alternatives that the agency intends to reduce chemical testing on mammals 30% by 2025 and end it altogether by 2035. [ 61 ] [ 134 ] [ 140 ] Scientists are also able to test vaccines on humans volunteers. Unlike animals used for research, humans are able to give consent to be used in testing and are a viable option when the need arises. The COVID-19 (coronavirus) global pandemic demonstrated that researchers can skip animal testing and go straight to observing how vaccines work in humans. One company working on a COVID-19 vaccine, Moderna Therapeutics, worked on developing a vaccine using new technology: instead of being based on a weakened form of the virus, it was developed using a synthetic copy of the COVID-19 genetic code. [ 142 ] [ 143 ] Read More

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Ethical care for research animals

WHY ANIMAL RESEARCH?

The use of animals in some forms of biomedical research remains essential to the discovery of the causes, diagnoses, and treatment of disease and suffering in humans and in animals., stanford shares the public's concern for laboratory research animals..

Many people have questions about animal testing ethics and the animal testing debate. We take our responsibility for the ethical treatment of animals in medical research very seriously. At Stanford, we emphasize that the humane care of laboratory animals is essential, both ethically and scientifically.  Poor animal care is not good science. If animals are not well-treated, the science and knowledge they produce is not trustworthy and cannot be replicated, an important hallmark of the scientific method .

There are several reasons why the use of animals is critical for biomedical research: 

••  Animals are biologically very similar to humans. In fact, mice share more than 98% DNA with us!

••  Animals are susceptible to many of the same health problems as humans – cancer, diabetes, heart disease, etc.

••  With a shorter life cycle than humans, animal models can be studied throughout their whole life span and across several generations, a critical element in understanding how a disease processes and how it interacts with a whole, living biological system.

The ethics of animal experimentation

Nothing so far has been discovered that can be a substitute for the complex functions of a living, breathing, whole-organ system with pulmonary and circulatory structures like those in humans. Until such a discovery, animals must continue to play a critical role in helping researchers test potential new drugs and medical treatments for effectiveness and safety, and in identifying any undesired or dangerous side effects, such as infertility, birth defects, liver damage, toxicity, or cancer-causing potential.

U.S. federal laws require that non-human animal research occur to show the safety and efficacy of new treatments before any human research will be allowed to be conducted.  Not only do we humans benefit from this research and testing, but hundreds of drugs and treatments developed for human use are now routinely used in veterinary clinics as well, helping animals live longer, healthier lives.

It is important to stress that 95% of all animals necessary for biomedical research in the United States are rodents – rats and mice especially bred for laboratory use – and that animals are only one part of the larger process of biomedical research.

Our researchers are strong supporters of animal welfare and view their work with animals in biomedical research as a privilege.

Stanford researchers are obligated to ensure the well-being of all animals in their care..

Stanford researchers are obligated to ensure the well-being of animals in their care, in strict adherence to the highest standards, and in accordance with federal and state laws, regulatory guidelines, and humane principles. They are also obligated to continuously update their animal-care practices based on the newest information and findings in the fields of laboratory animal care and husbandry.  

Researchers requesting use of animal models at Stanford must have their research proposals reviewed by a federally mandated committee that includes two independent community members.  It is only with this committee’s approval that research can begin. We at Stanford are dedicated to refining, reducing, and replacing animals in research whenever possible, and to using alternative methods (cell and tissue cultures, computer simulations, etc.) instead of or before animal studies are ever conducted.

Organizations and Resources

There are many outreach and advocacy organizations in the field of biomedical research.

• Learn more about outreach and advocacy organizations

Stanford Discoveries

What are the benefits of using animals in research? Stanford researchers have made many important human and animal life-saving discoveries through their work. 

• Learn more about research discoveries at Stanford

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• Animals in Laboratories

Animal Testing

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About Animal Testing

Humane Society International / Global

What is animal testing?

The term “animal testing” refers to procedures performed on living animals for purposes of research into basic biology and diseases, assessing the effectiveness of new medicinal products, and testing the human health and/or environmental safety of consumer and industry products such as cosmetics, household cleaners, food additives, pharmaceuticals and industrial/agro-chemicals. All procedures, even those classified as “mild,” have the potential to cause the animals physical as well as psychological distress and suffering. Often the procedures can cause a great deal of suffering. Most animals are killed at the end of an experiment, but some may be re-used in subsequent experiments. Here is a selection of common animal procedures:

• Forced chemical exposure in toxicity testing, which can include oral force-feeding, forced inhalation, skin or injection into the abdomen, muscle, etc.
• Exposure to drugs, chemicals or infectious disease at levels that cause illness, pain and distress, or death
• Genetic manipulation, e.g., addition or “knocking out” of one or more genes
• Ear-notching and tail-clipping for identification
• Short periods of physical restraint for observation or examination
• Prolonged periods of physical restraint
• Food and water deprivation
• Surgical procedures followed by recovery
• Infliction of wounds, burns and other injuries to study healing
• Infliction of pain to study its physiology and treatment
• Behavioural experiments designed to cause distress, e.g., electric shock or forced swimming
• Other manipulations to create “animal models” of human diseases ranging from cancer to stroke to depression
• Killing by carbon dioxide asphyxiation, neck-breaking, decapitation, or other means

What types of animals are used?

Many different species are used around the world, but the most common include mice, fish, rats, rabbits, guinea pigs, hamsters, farm animals, birds, cats, dogs, mini-pigs, and non-human primates (monkeys, and in some countries, chimpanzees). Video: Watch what scientists have to say about alternatives to animal testing .

It is estimated that more than 115 million animals worldwide are used in laboratory experiments every year. But because only a small proportion of countries collect and publish data concerning animal use for testing and research, the precise number is unknown. For example, in the United States, up to 90 percent of the animals used in laboratories (purpose-bred rats, mice and birds, fish, amphibians, reptiles and invertebrates) are excluded from the official statistics, meaning that figures published by the U.S. Department of Agriculture are no doubt a substantial underestimate.

Within the European Union, more than 12 million animals are used each year, with France, Germany and the United Kingdom being the top three animal using countries. British statistics reflect the use of more than 3 million animals each year, but this number does not include animals bred for research but killed as “surplus” without being used for specific experimental procedures. Although these animals still endure the stresses and deprivation of life in the sterile laboratory environment, their lives are not recorded in official statistics. HSI believes that complete transparency about animal use is vital and that all animals bred, used or killed for the research industry should be included in official figures. See some animal use statistics .

What’s wrong with animal testing?

For nearly a century, drug and chemical safety assessments have been based on laboratory testing involving rodents, rabbits, dogs, and other animals. Aside from the ethical issues they pose—inflicting both physical pain as well as psychological distress and suffering on large numbers of sentient creatures—animal tests are time- and resource-intensive, restrictive in the number of substances that can be tested, provide little understanding of how chemicals behave in the body, and in many cases do not correctly predict real-world human reactions. Similarly, health scientists are increasingly questioning the relevance of research aimed at “modelling” human diseases in the laboratory by artificially creating symptoms in other animal species.

Trying to mirror human diseases or toxicity by artificially creating symptoms in mice, dogs or monkeys has major scientific limitations that cannot be overcome. Very often the symptoms and responses to potential treatments seen in other species are dissimilar to those of human patients. As a consequence, nine out of every 10 candidate medicines that appear safe and effective in animal studies fail when given to humans. Drug failures and research that never delivers because of irrelevant animal models not only delay medical progress, but also waste resources and risk the health and safety of volunteers in clinical trials.

What’s the alternative?

If lack of human relevance is the fatal flaw of “animal models,” then a switch to human-relevant research tools is the logical solution. The National Research Council in the United States has expressed its vision of “a not-so-distant future in which virtually all routine toxicity testing would be conducted in human cells or cell lines”, and science leaders around the world have echoed this view.

The sequencing of the human genome and birth of functional genomics, the explosive growth of computer power and computational biology, and high-speed robot automation of cell-based (in vitro) screening systems, to name a few, has sparked a quiet revolution in biology. Together, these innovations have produced new tools and ways of thinking that can help uncover exactly how chemicals and drugs disrupt normal processes in the human body at the level of cells and molecules. From there, scientists can use computers to interpret and integrate this information with data from human and population-level studies. The resulting predictions regarding human safety and risk are potentially more relevant to people in the real world than animal tests.

But that’s just the beginning. The wider field of human health research could benefit from a similar shift in paradigm. Many disease areas have seen little or no progress despite decades of animal research. Some 300 million people currently suffer from asthma, yet only two types of treatment have become available in the last 50 years. More than a thousand potential drugs for stroke have been tested in animals, but only one of these has proved effective in patients. And it’s the same story with many other major human illnesses. A large-scale re-investment in human-based (not mouse or dog or monkey) research aimed at understanding how disruptions of normal human biological functions at the levels of genes, proteins and cell and tissue interactions lead to illness in our species could advance the effective treatment or prevention of many key health-related societal challenges of our time.

Modern non-animal techniques are already reducing and superseding experiments on animals, and in European Union, the “3Rs” principle of replacement, reduction and refinement of animal experiments is a legal requirement. In most other parts of the world there is currently no such legal imperative, leaving scientists free to use animals even where non-animal approaches are available.

If animal testing is so unreliable, why does it continue?

Despite this growing evidence that it is time for a change, effecting that change within a scientific community that has relied for decades on animal models as the “default method” for testing and research takes time and perseverance. Old habits die hard, and globally there is still a lack of knowledge of and expertise in cutting-edge non-animal techniques.

But with HSI’s help, change is happening. We are leading efforts globally to encourage scientists, companies and policy-makers to transition away from animal use in favour of 21st century methods. Our work brings together experts from around the globe to share knowledge and best practice, improving the quality of research by replacing animals in the laboratory.

Are animal experiments needed for medical progress?

It is often argued that because animal experiments have been used for centuries, and medical progress has been made in that time, animal experiments must be necessary. But this is missing the point. History is full of examples of flawed or basic practices and ideas that were once considered state-of-the-art, only to be superseded years later by something far more sophisticated and successful. In the early 1900’s, the Wright brothers’ invention of the airplane was truly innovative for its time, but more than a century later, technology has advanced so much that when compared to the modern jumbo jet those early flying machines seem quaint and even absurd. Those early ideas are part of aviation history, but no-one would seriously argue that they represent the cutting-edge of design or human achievement. So it is with laboratory research. Animal experiments are part of medical history, but history is where they belong. Compared to today’s potential to understand the basis of human disease at cellular and molecular levels, experimenting on live animals seems positively primitive. So if we want better quality medical research, safer more effective pharmaceuticals and cures to human diseases, we need to turn the page in the history books and embrace the new chapter—21st century science.

Independent scientific reviews demonstrate that research using animals correlates very poorly to real human patients. In fact, the data show that animal studies fail to predict real human outcomes in 50 to 99.7 percent of cases. This is mainly because other species seldom naturally suffer from the same diseases as found in humans. Animal experiments rely on often uniquely human conditions being artificially induced in non-human species. While on a superficial level they may share similar symptoms, fundamental differences in genetics, physiology and biochemistry can result in wildly different reactions to both the illness and potential treatments. For some areas of disease research, overreliance on animal models may well have delayed medical progress rather than advanced it. By contrast, many non-animal replacement methods such as cell-based studies, silicon chip biosensors, and computational systems biology models, can provide faster and more human-relevant answers to medical and chemical safety questions that animal experiments cannot match.

“The claim that animal experimentation is essential to medical development is not supported by proper, scientific evidence but by opinion and anecdote. Systematic reviews of its effectiveness don’t support the claims made on its behalf” (Pandora Pound et al. British Medical Journal 328, 514-7, 2004).

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Donate to help animals suffering in labs and other cruel situations, discover more.

Imagine a syringe being forced down your throat to inject a chemical into your stomach, or being restrained and forced to breathe sickening vapours for hours. That’s the cruel reality of animal testing for millions of mice, rabbits, dogs and other animals worldwide.

We’re giving the beauty industry a cruelty-free makeover with a wave of animal testing bans supported by hundreds of companies and millions of caring consumers worldwide.

We all dream of the day when cancer is cured and AIDS is eradicated, but is the continued use of mice, monkeys and other animals as experimental “models” of human disease actually holding us back from realizing the promise of 21st century science?

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Animal testing and experiments FAQ

How many animals are used in experiments each year?

Which animals are used in experiments, what kinds of experiments are animals used in, what kinds of institutions use animals in experiments, where do laboratories get the animals they use in experiments, what is life like for animals in laboratories, what happens to the animals once an experiment is over, aren’t there laws to protect animals used in experiments, why are animals still used in experiments, what are the alternatives to experiments on animals, what are the advantages of using non-animal alternatives instead of animals in experiments.

• What are you doing to end experiments on animals?

What can I do to help animals in laboratories?

Stand with us to demand that the federal government, state governments, companies and universities stop relying on outdated animal experiments.

It is estimated that more than 50 million animals are used in experiments each year in the United States. Unfortunately, no accurate figures are available to determine precisely how many animals are used in experiments in the U.S. or worldwide.

The U.S. Department of Agriculture (USDA) does compile annual statistics on some animals used in experiments, including cats , dogs , guinea pigs , hamsters , pigs , primates , rabbits and  sheep .

However, the animals most commonly used in experiments—“purpose-bred” mice and rats  (mice and rats bred specifically to be used in experiments)—are not counted in annual USDA statistics and are not afforded the minimal protections provided by the Animal Welfare Act. The Animal Welfare Act is a federal law that sets minimal standards for the treatment of certain warm-blooded animals used in experiments. The law also requires that unannounced inspections of all regulated animal testing facilities are carried out annually, although some facilities only receive partial inspections . In addition to purpose-bred mice and rats, animals such as crabs, fish , frogs, octopuses and turtles , as well as purpose-bred birds , are not covered by the Animal Welfare Act. The failure to protect these animals under the law means that there is no oversight or scrutiny of their treatment in the laboratory or the experiments performed on them. And, because these animals are not counted, no one knows how many of them are suffering in laboratories. It also means that facilities using unprotected species in experiments are not required to search for alternative, non-animal methods that could be used to replace or reduce harmful experiments that use animals.

View Animals Used in Experiments by State

View Dogs Used in Experiments by State

Read Dogs Used in Experiments FAQ

Use our Animal Laboratory Search Tool  to find information about universities, hospitals, companies and other organizations that use certain animals in experiments

View a list of U.S. laboratories that use certain animals in experiments ; click on “License Type” and select “Class R – Research Facilities." Note that numbers only include animals covered by the Animal Welfare Act.

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Animals used in experiments include baboons, cats , cows , dogs , ferrets,  fish , frogs, guinea pigs , hamsters , horses , llamas, mice , monkeys (such as marmosets and macaques), owls, pigs , quail, rabbits , rats and  sheep .

Chimpanzees have thankfully not been subjected to invasive experiments in the U.S. since 2015, when federal decisions were made to prevent their use. Despite this, hundreds of chimpanzees are still languishing in laboratories while they wait to be moved to sanctuaries.

Animals are used in many different kinds of experiments. These are just a few examples:

• Dogs have their hearts, lungs or kidneys deliberately damaged or removed to study how experimental substances might affect human organ function.  
• Monkeys are taken from their mothers as infants to study how extreme stress might affect human behavior.
• Mice are force-fed daily doses of a chemical for two years to see if it might cause cancer in humans.
• Cats have their spinal cords damaged and are forced to run on treadmills to study how nerve activity might affect human limb movement.
• Ferrets are deliberately infected with extremely painful, potentially fatal diseases (such as RSV, COVID-19 or Ebola) and not given pain relief or treatment before their death to study how humans might be affected by the same disease.  
• Pigs are implanted with various devices (such as pacemakers and dental implants) to study how human bodies might respond to such devices.  
• Pregnant rabbits are force-fed toxic pesticides every day for several weeks to study how human mothers and babies might be affected if they were exposed to the pesticides.
• Sheep are subjected to high pressures (such as those experienced deep underwater) for hours at a time and then returned to normal pressure so that their response can be observed.
• Rats are placed in small tubes and are forced to inhale cigarette smoke for hours at a time to study how humans might respond to cigarette smoke.   
• Baboons are injected with endometrial tissue to induce painful symptoms of endometriosis and study how humans might be affected by the disorder.
• Horses are infected with a potentially fatal virus (such as hepatitis) and their symptoms monitored to study how humans might be affected by the same virus.

Experiments are often excruciatingly painful for the animals used and can vary in duration from days to months to years. The experiment can cause vomiting, diarrhea, irritation, rashes, bleeding, loss of appetite, weight loss, convulsions, respiratory distress, salivation, paralysis, lethargy, bleeding, organ abnormalities, tumors, heart failure, liver disease, cancer and death.

There is no limit to the extent of pain and suffering that can be inflicted on animals during experiments. In some instances, animals are not given any kind of pain medication to help relieve their suffering or distress during or after the experiment on the basis that it could affect the experiment.

Animals are typically killed once an experiment is over so that their tissues and organs can be examined, although it is not unusual for animals to be used in multiple experiments over many years. There are no accurate statistics available on how many animals are killed in laboratories every year.

Read Cosmetics Animal Testing FAQ

• Read about our 2022 undercover investigation at Indiana laboratory Inotiv, one of America’s largest animal testing labs. We documented hundreds of dogs, monkeys, rats and pigs undergoing experiments, including terrified beagle puppies being force-fed a potentially toxic drug in cruel and ineffective months-long tests paid for by Crinetics, a pharmaceutical company in San Diego.
• Read about our 2019 undercover investigation at a Michigan laboratory where thousands of dogs are killed every year. After weeks of pressure from the public, the pesticide company that had commissioned a year-long fungicide test on 32 dogs agreed that the test was unnecessary and released the dogs to one of our shelter partners to be adopted.

Chemical, pesticide and drug companies (as well as contract laboratories that carry out tests for those companies), public and private universities, community and technical schools, government facilities, Veterans Affairs (VA) facilities and hospitals all use animals in experiments.

View Chart of Institutions That Use Dogs in Experiments

The majority of animals in laboratories are “purpose-bred” meaning that they are bred specifically to be used in experiments. People who breed and sell certain purpose-bred animals are called Class A dealers and are licensed and inspected by the U.S. Department of Agriculture (USDA). Facilities that only sell purpose-bred mice, rats, birds or cold-blooded animals such as crabs, fish, frogs, octopuses and turtles to laboratories are excluded and are not licensed or inspected by the USDA.

Some animals used in experiments are taken from the wild—including birds and  monkeys . 

Historically, some cats and dogs  were sold to laboratories by brokers known as random source Class B dealers, who acquired animals at auctions, from newspaper ads and various other sources, including animal shelters. Random source Class B dealers have not been allowed to operate since 2015 when Congress first passed legislation to prevent them from being licensed.  

Some cats and dogs in laboratories are still obtained directly from animal shelters, a practice known as “pound seizure.” Pound seizure laws vary from state to state with one state (Oklahoma) requiring shelters to give cats and dogs to laboratories, rather than euthanizing them, and others allowing or prohibiting laboratories from taking animals from animal shelters. Some states have no laws at all, leaving it up to the individual shelter or locality.

View Pound Seizure Laws by State

Animals in laboratories suffer immensely. In addition to the painful experiments that the vast majority of animals in laboratories experience over days, months, years or even decades, life in a laboratory is typically a miserable and terrifying experience.

Typically kept alone in barren steel cages with little room to move around and few, if any, comforts, such as toys or soft bedding, animals often become excruciatingly lonelyand anxious, often devoid of the companionship of other animals or the loving touch of a human. Animals in laboratories can associate humans with painful situations and, with no way to hide or get away, they panic whenever a person approaches their cage or freeze with fear when they are taken into treatment rooms. Despite this, dogswill often still seek out human attention.

Animals in laboratories typically also have to watch (or hear) other animals suffering, including their own parents, siblings or babies. High levels of constant stress can cause animals to exhibit unnatural behaviors. For example, it is not uncommon for monkeys to mutilate themselves or to rock or vocalize constantly as a way to help relieve their anxiety, mice to overgroom each other until they are completely bald, and dogs to continually pace.  

Very often the experiments themselves lead to suffering and death. In our 2022 undercover investigation we documented monkeys in “restraint chairs”—devices that are used to hold monkeys in place while the experiments are carried out—who accidentally hanged themselves while unattended. We also documented a dog named Riley used to test a substance so toxic that it brought him near death after only two days of forced dosing. He was hypersalivating, trembling, vomiting, and moaning, yet was dosed yet again with this highly toxic substance. Later, he lay on the floor, unable to stand. Our undercover investigator tried to comfort him while he was dying, but Riley was left to suffer in excruciating pain overnight because the laboratory’s veterinarian was unavailable on a weekend

Animals in laboratories are also subject to mistreatment by inexperienced or careless staff. Although there are penalties for laboratories when animals are injured or killed due to negligence or when they fail to meet minimum standards of animal care, in reality, the fines are typically either very small or waived entirely.

In some cases, animals die as a deliberate result of the experiment. For example, the LD50 (lethal dose 50%) test, which is typically performed on mice, rats, pigeons, quail and fish, involves determining the dose of a substance (such as a pesticide) that kills (or would lead to the death of) 50% of the animals tested.

It is extremely rare that animals are either adopted out or placed into a sanctuary after research is conducted on them. However, more and more states are passing laws that require laboratories, when possible, to offer dogs and cats to shelters and other rescue organizations so they can be adopted into loving homes after the experiments they were used in have ended. As of December 2023, 16 states have such laws.

The Animal Welfare Act was designed to protect certain animals, like dogs and monkeys, used in experiments, but the law only offers minimal standards for housing, food and exercise. The Animal Welfare Act also stipulates that the proposed experiments be reviewed by an Institutional Animal Care and Use Committee, whose members are appointed by the laboratory itself and largely made up of employees of the institution. A 2014 audit report reviewing Animal Welfare Act oversight of laboratories found that “animals are not always receiving basic humane care and treatment and, in some cases, pain and distress are not minimized during and after experimental procedures.”

The animals most commonly used in experiments—“purpose-bred” mice and rats  (mice and rats bred specifically to be used in experiments)—are not counted in annual USDA statistics and are not afforded the minimal protections provided under the Animal Welfare Act. The Animal Welfare Act is a federal law that sets minimal standards for the treatment of certain warm-blooded animals used in experiments. The law also requires that unannounced inspections of all regulated research facilities are carried out annually. In addition to purpose-bred mice and rats, animals such as crabs, fish , frogs, octopuses and turtles as well as purpose-bred birds are not covered by the Animal Welfare Act. The failure to protect these animals under the law means that there is no oversight or scrutiny of their treatment and use in the laboratory. And, because these animals are not counted, no one knows how many of them are suffering in laboratories. It also means that facilities using unprotected species in experiments are not required to search for alternative, non-animal methods that could be used to replace or reduce harmful experiments that use animals.

The vast majority of experiments on animals are not required by government law or regulations. Despite that, government agencies often seem to prefer that companies carry out animal tests to assess the toxicity or efficacy of products such as industrial chemicals, pesticides, medical devices and medicines.

For example, the Environmental Protection Agency (EPA) requires that a new pesticide be fed to dogs for 90 days as part of its evaluation and approval process. The Food and Drug Administration (FDA), which regulates various products such as drugs, medical devices, food, fragrances and color additives, will not approve potential drugs unless they are first tested on animals, which usually includes dogs. In addition to tests on  dogs ,  mice and rats ,  rabbits ,  birds  and primates are also used to test pesticides and drugs. These types of tests have been performed for years, regardless of whether they provide valuable information. While some regulatory agencies, like the EPA, are now taking a critical look at these animal tests to determine if they provide information necessary for assessing how safe a product or substance is for humans, and if better approaches are available, others have done little. More efforts can be made by agencies to invest in and encourage the development of non-animal methods.

Swapping animal experiments for non-animal alternative methods seems like a straightforward process, given that using animals has so many limitations and sophisticated new technologies offer countless possibilities for creating methods that are more humane and that more accurately mimic how the human body will respond to drugs, chemicals or treatments. Unfortunately, developing these alternatives is a complex process facing many obstacles, including inadequate funding. In most cases, a non-animal alternative must be formally validated—historically an expensive and lengthy process—in order to be accepted by government regulatory agencies, both in the U.S. and globally, although new, faster approaches to approving these methods are being developed. In contrast, animal experiments have never been subjected to the same level of scrutiny and validation. Despite these challenges, many scientists are increasingly committed to developing and using non-animal methods.

The world is continuously moving toward a future dominated by sophisticated methods that use human cells, tissues and organs, 3D printing, robotics, computer models and other technologies to create experiments that do not rely on animals.

While many animal experiments have not changed since they were developed decades ago and will always have severe limitations, advanced non-animal methods represent the very latest techniques that science has to offer, provide countless possibilities to improve our understanding and treatment of human diseases and will only continue to improve over time. Non-animal methods also have several advantages over outdated animal experiments: they more closely mimic how the human body responds to drugs, chemicals and treatments; they are more efficient and often less expensive; and they are more humane. Ultimately, moving away from animal experiments is better for both humans and animals.

We advocate for the immediate replacement of animal experiments with available non-animal methods and for more funding to develop new non-animal methods. A concerted effort to shift funding and technological development toward more non-animal alternatives will lead us to a future where animal experiments are a thing of the past.

Examples of non-animal alternative methods

• “Organs-on-chips” are tiny 3D chips created from human cells that look and function like miniature human organs. Organs-on-chips are used to determine how human systems respond to different drugs or chemicals and to find out exactly what happens during infection or disease. Several organs, representing heart, liver, lungs or kidneys, for example, can be linked together through a “microfluidic” circulatory system to create an integrated “human-on-a-chip” model that lets researchers assess multi-organ responses.
• Sophisticated computer models use existing information (instead of carrying out more animal tests) to predict how a medicine or chemical, such as drain cleaner or lawn fertilizer, might affect a human.
• Cells from a cancer patient’s tumor are used to test different drugs and dosages to get exactly the right treatment for that specific individual, rather than testing the drugs on animals.
• Specialized computers use human cells to print 3D tissues that are used to test drugs.
• Skin cells from patients, such as those with Alzheimer’s disease, are turned into other types of cells (brain, heart, lung, etc.) in the laboratory and used to test new treatments.
• Sophisticated computer programming, combined with 3D imaging, is used to develop highly accurate 3D models of human organs, such as the heart. Researchers then input real-world data from healthy people and those with heart disease to make the model hearts “beat” and test how they might respond to new drugs.

Human cells or synthetic alternatives can replace horseshoe crab blood in tests to determine whether bacterial contaminants are present in vaccines or injectable drugs.

• Animal experiments are time-consuming and expensive.
• Animal experiments don’t accurately mimic how the human body and human diseases respond to drugs, chemicals or treatments.
• Animals are very different from humans and, therefore, react differently.
• Increasing numbers of people find animal testing unethical.
• There are many diseases that humans get that animals do not.

What are you doing to end experiments on animals?

We advocate for replacing animals with non-animal alternative methods when they are available and more funding for the development of new alternative methods to quickly replace antiquated and unreliable animal tests and experiments. Our two main areas of focus are ending cosmetics animal testing  and ending experiments on dogs .

Cosmetics testing on animals

We—along with our partner, Humane Society International —are committed to ending cosmetics animal testing forever. Through our  Be Cruelty-Free campaign, we are working in the United States and around the globe to create a world where animals no longer have to suffer to produce lipstick and shampoo. 

• In the United States, we are working to pass the Humane Cosmetics Act , federal legislation that would prohibit animal testing for cosmetics, as well as the sale of animal-tested cosmetics.
• We are also working in several U.S. states to pass legislation that would end cosmetics animal testing. As of March 2024, 12 states (California, Hawai'i, Illinois, Louisiana, Maine, Maryland, Nevada, New Jersey, New York, Oregon, Virginia and Washington) have passed laws banning the sale of animal-tested cosmetics.
• Internationally, as of December 2023, 45 countries have passed laws or regulations to ban cosmetics animal testing, including every country in the European Union, Australia, Brazil, Canada, Chile, Colombia, Ecuador, Guatemala, Iceland, India, Israel, Mexico, New Zealand, Norway, South Korea, Switzerland, Taiwan, Turkey, the United Kingdom.
• We work with scientists from universities, private companies and government agencies around the globe to promote the development, use and regulatory acceptance of non-animal test methods that will reach beyond cosmetics.
• We educate consumers about animals used in cruel and unnecessary cosmetics tests and how to shop for cruelty-free cosmetics and personal care products.

Experiments on dogs

There is no place for harmful experiments on dogs in the U.S. We are committed to ending this practice.

• In the summer of 2022, we led the removal of 3,776 beagles from Envigo, a facility in Virginia that bred dogs to sell to animal laboratories. This historic mission was the result of a lawsuit filed by the U.S. Department of Justice that described shocking violations of the Animal Welfare Act at the facility. Instead of continuing to suffer, the dogs were removed from Envigo and headed to loving homes , a process facilitated by our shelter and rescue partners around the country.
• In April 2022, we released the results of our undercover investigation at Inotiv, an Indiana laboratory where thousands of dogs, monkeys, pigs and rats are used in experiments and killed.
• In 2021, we released a report examining the U.S. government’s role in using dogs in experiments. We found that the government uses millions of taxpayer dollars to fund harmful experiments on dogs each year—and also seems to prefer that companies carry out dog tests. Our researchers scrutinized public records and found that between 2015 and 2019, the National Institutes of Health (NIH) awarded more than $200 million to 200 institutions for 303 projects that used dogs in harmful experiments. Dogs were subjected to multiple surgeries, fitted with equipment to impair their heart function and implanted with devices to alter normal bodily functions. Following the conclusion of an experiment, dogs are typically killed instead of being adopted into loving homes.
• In 2019, we released the results of our undercover investigation at a Michigan laboratory where thousands of dogs are killed every year. After weeks of pressure from the public, the pesticide company that had commissioned a test year-long fungicide test on 32 dogs, agreed that the test was unnecessary and released the dogs to one of our shelter partners so they could be adopted.
• After a recent analysis we performed that showed the 90-day dog test for pesticide registration was rarely used by the Environmental Protection Agency (EPA) to assess the risk that pesticides pose to humans, we are urging the agency to eliminate or significantly limit this test in the near future. We also want the agency to reaffirm their previously stated commitment to end their reliance on using mammals to test pesticides and chemicals by 2035.
• We are asking the Food and Drug Administration (FDA) to support the development of alternative methods that replace dogs in experiments. 
• We want the Department of Veterans Affairs (VA) to adopt the recommendations of an independent panel review released in 2020 that analyzed VA experiments using dogs, identified several areas where dogs are not needed and urged the agency to develop a strategy to replace all animal use. 
• We are recommending that the National Institutes of Health (NIH) scrutinize grant proposals for projects using dogs, by applying strict criteria that must be met before dogs can be used and that they ban the use of dogs in experiments that cause unrelieved pain. We are also requesting that the NIH define a date when they will no longer fund or support experiments on dogs.
• prohibit or limit the use of dogs in experiments not required by federal law, similar to laws passed in California and Illinois .
• ensure an opportunity for  dogs and cats to be adopted into loving homes after the experiment ends.
• strengthen regulatory oversight of facilities that breed dogs destined for laboratories and increase penalties for animal welfare violations.
• Direct state funding to support the research and development of modern non-animal technologies, similar to the law passed in Maryland .

One easy way to help animals suffering in cosmetics tests is to swap out your personal care and household products for cruelty-free versions! Cosmetics (such as shampoo, deodorant and lipstick) and household products (such as dish soap, laundry detergent and glass cleaner) are typically tested on guinea pigs , rabbits ,  mice and rats .

Help us demand better for animals used in experiments through the following actions:

• Tell the FDA to stop encouraging companies to test on animals and instead switch to sophisticated non-animal alternatives.
• Stand with us to end research and tests on dogs by signing our petition.
• Urge the USDA to do their job and help protect animals in laboratories.
• Ask your federal legislators in Congress to ban cosmetic tests on animals.
• Support efforts to replace animal experiments with advanced non-animal alternatives that are better for both human health and animal welfare.

Follow us on Facebook to learn the latest news and actions related to animals in laboratories!

Alternatives to horseshoe crab blood

The Humane Society of the United States urges that horseshoe crab blood be replaced with non-animal methods when conducting endotoxin tests for medical products.

Vaccine, injectable drug and medical device manufacturers must test for endotoxins, a type of bacterial contaminant that, if present, can cause patients to develop symptoms that can include fever, chills, headache and nausea. Blood from horseshoe crabs is used to conduct the Limulus amebocyte lysate (or LAL) test for endotoxins.

The problem

To create this test, horseshoe crabs are captured from the wild and up to 30% of their blood is removed by medical supply companies. The crabs are later returned to the wild; however, it is estimated that 10-15% or more of them die as a result of this process.

In addition to being collected for their blood, horseshoe crabs are gathered up by fisheries, which use them as bait. These practices have led to a rapid decrease in the horseshoe crab population, putting them at risk of extinction. The decrease in wild horseshoe crab populations also impacts other species, including migratory shorebirds like the red knot, a threatened species that depends on horseshoe crab eggs for food.

THE solution

Scientists have developed recombinant Factor C (rFC), a synthetic alternative to the protein in horseshoe crab blood that can detect bacterial endotoxins. Repeated studies have demonstrated that rFC is equivalent or superior to the LAL test. A second method—the monocyte activation test—uses human cells and can not only detect bacterial endotoxins, but also pyrogenic (fever-causing) non-endotoxins.

what should be done

As a member of the Horseshoe Crab Recovery Coalition, the Humane Society of the United States is advocating for the replacement of the Limulus amebocyte lysate test with recombinant Factor C (rFC) or the monocyte activation test (MAT).

We urge the U.S. Pharmacopoeia—which sets quality, purity, strength and identity standards for medicines, food ingredients and dietary supplements—to encourage manufacturers to use rFC or MAT rather than LAL.

We also urge the U.S. Food and Drug Administration to update its guidance for vaccine, injectable drug and device manufacturers to indicate that these non-animal tests are now the preferred methods for endotoxin and pyrogenicity testing.

Donate today and your gift can have TRIPLE the impact to help save more animals from suffering.

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• Published: 29 September 2004

Use of animals in experimental research: an ethical dilemma?

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Gene Therapy volume  11 ,  pages S64–S66 ( 2004 ) Cite this article

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Mankind has been using animals already for a long time for food, for transport and as companion. The use of animals in experimental research parallels the development of medicine, which had its roots in ancient Greece (Aristotle, Hippocrate). With the Cartesian philosophy in the 17th century, experiments on animals could be performed without great moral problems. The discovery of anaesthetics and Darwin's publication on the Origin of Species, defending the biological similarities between man and animal, contributed to the increase of animal experimentation. The increasing demand for high standard animal models together with a critical view on the use of animals led to the development of Laboratory Animal Science in the 1950s with Russell and Burch's three R's of Replacement, Reduction and Refinement as guiding principles, a field that can be defined as a multidisciplinary branch of science, contributing to the quality of animal experiments and to the welfare of laboratory animals. The increased interest in and concern about animal welfare issues led to legislative regulations in many countries and the establishment of animal ethics committees.

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Van Zutphen LFM . History of animal use. In: Van Zutphen LFM, Baumans V, Beynen AC (eds). Principles of Laboratory Animal Science . Elsevier: Amsterdam, 2001, pp 2–5.

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Dennis Jr MB . Welfare issues of genetically modified animals. ILAR J 2002; 43 : 100–109.

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Russell WMS, Burch RL . The Principles of Humane Experimental Technique . Methuen: London, 1959, Reprinted by UFAW, 1992: 8 Hamilton Close, South Mimms, Potters Bar, Herts EN6 3QD England.

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Explainer: What Is Animal Testing?

Vaccines, medications and cosmetics rely on animal testing even though the process is cruel, unreliable and often inaccurate.

Explainer • Animal Testing • Policy

Words by Björn Ólafsson

The use of animals in experiments is so endemic that “guinea pig” is used as an alternative term for “test subject.” But underlying this ubiquity is a set of processes that harm animals unnecessarily: rats force-fed drugs designed to induce tumors, monkeys kept in tiny cages with chemicals irritating their skin and beagles euthanized without any anesthesia.

Critics say many of these experiments are unreliable and even unnecessary. Advocates for reduced animal testing earned a win in December 2022: the FDA announced that it would no longer require animal tests prior to approving a drug for human trials.

What Is Animal Testing?

Animal testing, sometimes called in vivo testing, is a process of determining if certain medications, vaccines and cosmetics are safe for humans by first experimenting with them on animals. Animal testing is common in most countries and has been used in some forms throughout much of human history.

Cosmetic Testing

Cosmetic testing is a process of using animals to test any cosmetic product before human use, such as makeups, lotions, creams, fragrances, oils or facial masks. 

Testing for Medicine

Medical testing involves using animals to examine new drugs, research biological systems, investigate genetic factors, delve into animal psychologies or test out surgical strategies. Nowadays, drugs are the most common form of medical testing on animals.  

The History of Animal Testing

Animal testing is a long-documented practice, with some of the oldest instances dating back to around 300 B.C. in ancient Greece. Yet while animal testing was widespread in the form of vivisection and practice for operations, it wasn’t until the 20th century that medicines were commonly tested on animals. In fact, several laws were passed in this period, including the 1938 Federal Food, Drug, and Cosmetic Act in the U.S., that encouraged or mandated the use of animals in testing before human consumption. 

What Types of Animals Are Used in Animal Testing?

Invertebrates.

Common invertebrates used in animal testing include fruit flies and nematode worms. Unfortunately for these animals, no federal protections exist to minimize their pain or suffering in the U.S.

Vertebrates

There’s truth in the common phrase “lab rat” — 95 percent of animals used in animal testing are mice or rats. Dogs, cats, pigs, monkeys, other primates, rabbits and sheep are all used in addition to rodents. 

How Many Animals Are Used in Experiments Each Year?

This is a difficult question to answer, because the U.S. Department of Agriculture only counts certain species of animals in its annual review of animal testing. Mice and rats specifically bred for testing purposes are not counted because they do not fall under the U.S. Animal Welfare Act.

However, it’s been estimated that at least 50 million animals are used in the U.S. every year. The real number is unknown and may be higher. Worldwide, exact numbers are unknown, but some estimate the number to be around 200 million experiments per year. 

What’s Wrong With Animal Testing?

Is animal testing painful.

Some researchers attempt to reduce the pain for animal test subjects, but many do not. According to the USDA animal usage summary report , roughly 8 percent of animals were experimented on with no measures taken to ensure pain reduction. This report does not take into account animals that do not fall under the Animal Welfare Act, so the real number is unknowable and likely much higher. 

Even animals protected by the Animal Welfare Act are often subjected to levels of pain that are hard to comprehend. Of all surgeries on animals, 40 percent do not report using anesthesia, and drugs are often force-fed to animals. Animals are also often killed after the experiments are completed, long before the end of their natural lifespan.  

Are Animal Testing Results Reliable?

Animal tests do not catch all possible side effects before drugs move to a later phase of testing. According to a 2004 report from the USDA, 92 percent of medicines that pass an animal testing phase will not proceed to market, and a major cause of this failure is safety problems that were not predicted by animal tests. More recent reports from scientists estimate an even higher number of 96 percent . 

There are a variety of reasons why animal tests are considered unreliable. According to a 2015 review in the Cambridge Quarterly of Healthcare Ethics , these include the effects of laboratory conditions; the different ways that diseases impact animals and humans; and the differences in physiology and genetics across species, all of which lead to inaccuracies. Due to such factors, a breakthrough meta-analysis published in Alternatives to Laboratory Animals in 2015 argued that a lack of toxicity of a drug in any of the five species most commonly used in animal testing — dogs, rats, mice, rabbits and monkeys — was not able to indicate the likelihood of a similar lack of toxicity in humans. In other words, animal tests don’t work. 

Advocates for animal testing often argue that the complexity of a living organism — the organs, circulatory system and genetic regulation — will affect drugs in a way that single tissue samples cannot. This argument fails to account for the fact that nonhuman systems are very different from human systems, which leads to inaccuracy. 

Animal testing can also lead to banning drugs that would benefit humans. For example, tamoxifen , a drug used to treat breast cancer, can cause tumors in rodents. If this drug had been tested on animals in early phases of research, it is likely the benefits of tamoxifen would have remained untapped. 

Is Animal Testing Cruel?

Due to the combination of low accuracy and high amounts of pain, it is difficult to argue that animal testing is not cruel. Animals such as rats, mice, dogs and chimpanzees are burned, poisoned, crippled, starved or abused in other ways via drugs, confinement or other invasive procedures.

Animals like these are sensitive to pain, emotionally empathetic and capable of forming social bonds. But to the researchers in charge of them, they are nothing more than tools. 

Is Animal Testing Archaic?

Due to the inaccuracy of animal testing, voices have arisen to criticize its outdated methodology. Not only is animal testing an old-fashioned practice that hasn’t been brought into the 21st century, but evidence shows it is likely holding back medical research. 

Is Animal Testing Wasteful?

Because of the inaccuracy of animal testing, many scientists and experts argue that its existence is inherently wasteful. British doctor Ian Roberts writes that “biased or imprecise results from animal experiments may result in clinical trials of biologically inert or even harmful substances, thus . . . wasting scarce research resources.”

Is Animal Testing Illegal?

Cosmetics testing has been banned in 42 countries and 10 U.S. states (California, Hawaii, Illinois, Maine, Maryland, Nevada, New Jersey, Louisiana, New York and Virginia). New York’s ban on cosmetic testing goes into effect in January 2023 , which makes it possible that more states will continue to follow their lead. 

No countries currently ban medical animal testing, but this may soon change. This year, Switzerland held a referendum on medical animal testing. A large Swiss pharmaceutical lobby campaigned against the initiative, which was ultimately unsuccessful. But the fact that animal testing went from untouchable fact to subject of a national debate sparks doubt about its continued acceptance in the future. 

Aren’t There Laws To Protect Animals Used in Experiments?

There do exist some laws to protect animals, such as the U.S. Animal Welfare Act. However, this law does very little to protect animals from pain, and doesn’t even count rats and mice as protected animals.

Cosmetic testing is far more controversial in the public sphere and therefore more heavily regulated. It is almost entirely banned in the European Union and other countries, including Guatemala, Colombia, India, Taiwan and the U.K. The U.S. has no federal cosmetics ban.

Why Are Animals Still Used in Experiments?

Despite the lack of sustained evidence for animal testing’s usefulness, and the possibility of cheaper alternatives (as discussed below), animal testing seems to be used far more often than it should be. Why?

First of all, the pharmaceutical industry has maintained a clear interest in preserving animal testing, and only very rarely review evidence about its actual usefulness. Another issue is scientific tradition and established practice. Scientists are likely to cite historical precedent as a reason for selecting an animal model, as opposed to the model’s similarity to human systems or effectiveness in predicting toxicity, according to a 2019 paper in Alternatives to Animal Experimentation . 

Should Animal Testing Be Banned?

Calls to ban animal testing because of its ineffectiveness and cruelty have been getting louder in recent years. Entire conferences are held to discuss alternatives to animal testing, and many petitions and campaigns are igniting across the world. These voices don’t just originate from the animal liberation movement, either. Prominent scientists , pharmaceutical bosses and concerned citizens are joining the chorus. 

Alternatives to Animal Testing

Thankfully, there exist several alternatives to animal testing, some of which have become more popular and common in recent years. 

In Vitro Testing

In vitro testing is a process of conducting an examination in a test tube using tissue samples.

Human Tissues

Real human tissue samples, which can be ethically donated to science as a result of surgeries or after death, are viable alternatives for testing localized drugs. For years, research has indicated that various in vitro methods can hypothetically outperform animal testing (and cost less too), although this form of testing is likely best used for understanding toxicity within a single organ or organ system, not the entire human body. 

A new human tissue testing method has emerged recently that shows promise. An in vitro skin testing model called h-CLAT recently entered use in Europe and Japan, paving the way for more techniques that don’t require animal experimentation. 

In Vitro Modeling Systems

Another form of in vitro testing involves a synthetic model that can replicate human systems. While less accurate, this method is cheaper and far easier to source, although it is best used for simpler human organs like the skin. One example, the EpiDerm technology , is already widespread for cosmetic purposes. This method is currently not used for large-scale medicinal approval, but instead to test if certain people are at risk for certain diseases. 

Computer Modeling 

Of all the alternatives, scientists are most excited about computer modeling techniques. Advanced computer modeling, sometimes called in silica testing, can create complex models of human body systems, even accounting for irregularities like prior diseases, as well as a vast array of genetic and demographic information. 

And they work better than animal models. A 2018 study found an accuracy rate of between 89 percent and 96 percent , while a 2017 study estimated the accuracy rate of one method of analysis at 96 percent : in both studies the computer models beat the animal testing experiments. 

Research Using Human Volunteers

Using human volunteers seems a bit dystopian, but science has progressed a long way since the unethical days of the 20th century. For starters, in some recent drug testing human volunteers only receive a microdose of the drug and are monitored in the presence of medical professionals to ensure safety. This microdosing method is promising, but still needs more research. Other forms of human volunteer research include the safe use of fMRI imaging, which has been shown to be very effective. 

Of course, ethics regarding human volunteers are critical. Scientists and researchers must take great caution not to compel participants into doing something unsafe and must mitigate risks as much as possible. Using human volunteers is also best done after one other method, like computer modeling, has been completed to mitigate risk. 

Animal Testing Facts and Statistics

• The majority of animals used in animal testing are exempt from the Animal Welfare Act because they are rats or mice.
• Rats have great memories and demonstrate empathy for other animals.
• Every year, the NIH spends nearly $20 billion on animal testing-based research.
• A majority of Americans disapprove of the continued use of animal testing.

What You Can Do

Consumers who want to avoid products tested on animals can look for a “vegan” or “cruelty-free” label when purchasing cosmetic products. They can also voice their support for policies to improve animal welfare in the medical industry like the FDA Modernization Act 2.0 , which passed the U.S. Senate earlier this year.

Independent Journalism Needs You

Björn Jóhann Ólafsson is a science writer and journalist who cares deeply about understanding the natural world and her inhabitants through stories and data. He reports on the environmental footprint of the meat industry, the alternative protein sector and cultural attitudes around food. His previous bylines include the EU Observer and Elemental. He lives in Spain with his two lovebirds.

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Ethics of Medical Research with Animals

U.S. Law and Animal Experimentation: A Critical Primer

Every country’s law permits medical experimentation on animals. While some countries protect particular kinds of animals from being subject to experimentation—notably great apes and endangered species—very few place concrete limitations on what researchers may cause animals to suffer, given sufficient scientific justification. What laws do, instead, is establish standards for the humane treatment and housing of animals in labs, and they encourage researchers to limit or seek alternatives to the use of animals, when doing that is consistent with the scientific goals of their research. The result, of course, is that no existing regulatory scheme is satisfactory to opponents of animal research. The law, in their view, does nothing more than make the animal research scientist into a sort of James Bond villain: superficially polite, offering fine housing and well-prepared cuisine even to those whom he intends, eventually, to kill.

Of course, the goals of animal experimentation law seem much more reasonable if one accepts that research on animals is both important for medical progress and morally permissible. On those assumptions, it makes a great deal of sense for the law to aim primarily at limiting unnecessary animal suffering even as it licenses scientifically justified experimentation. U.S. law accepts those assumptions and adopts that aim.

The system that has evolved in the United States combines elements of sometimes competing regulatory philosophies. The result is a complex, multilayered system that addresses the most important concerns, but, partly because of historical accident, also leaves some gaps. Even proponents of medical research on animals can see obvious ways in which the regulatory structure could be changed to benefit animals. Perhaps more important, though, is the fact that the existing regulatory structure, imperfect though it may be, is elastic enough to accommodate substantial changes that could reduce unnecessary animal suffering.

Multiple Regulatory Approaches

Animal welfare laws must address three main ways in which unnecessary animal suffering can occur in the context of medical experimentation. First, such suffering can occur when a given research protocol is not well justified scientifically. An experiment that was so badly designed that it could never generate any useful scientific knowledge would never warrant animal suffering. Harder cases result when the amount of suffering is ratcheted down, or the experiment’s potential to generate useful knowledge is ratcheted up. A legal regime concerned with avoiding this kind of unnecessary suffering can opt to trust in the judgment of each individual research scientist, or empower someone besides the researcher to make at least some baseline assessment of the scientific value of each new animal research protocol. It can also provide information and guidance to researchers or overseers to improve their decisions.

Second, unnecessary suffering can occur when the amount of animal suffering induced by an experiment is not strictly required to conduct the experiment—perhaps because more animals are used than are necessary; or because less sentient animals could be substituted for more sentient ones, or computer or tissue models substituted for animals entirely; or because crude experimental procedures are producing avoidable stress or pain. A legal framework seeking to avoid these kinds of unnecessary suffering will encourage or require researchers to use the three Rs: reduce (the number of animals used in experiments), replace (animals with nonanimals, higher-order animals with lower), and refine (experimental procedures causing pain or distress). [1]

Third, unnecessary suffering can occur outside the actual research protocol yet still in the research setting because of inappropriate animal handling, housing, and feeding practices. A legal regime seeking to avoid this kind of suffering will dictate humane standards for animal housing and care.

Given these goals, what sort of regulatory scheme would be best at realizing them? One can imagine a variety of available approaches, from strong, centralized state regulation and monitoring of all experimentation to a hands-off reliance on professional self-regulation among laboratory researchers. On the world stage, the United Kingdom is closest to taking the former approach, Japan to the latter. U.S. law falls somewhere in the middle, in part because U.S. law in this area is in fact the result of a gradual, decades-long merging of the government regulatory and professional self-regulatory approaches. [2]

The government regulatory approach is embodied in the sprawling, strange, and often amended Animal Welfare Act of 1966. In its original form, the AWA was designed to control pet breeding and sale practices; it was passed, in part, as a result of public outcry about the mistreatment of dogs sold to laboratories. As amended, it governs the treatment of animals in a wide range of settings, from pet shops to circuses and from zoos to laboratories. Its enforcement is delegated to the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, whose inspectors make unannounced site visits to research facilities. Violations uncovered on such visits can result in fines and even, in extreme cases, criminal prosecution. The most common complaint about enforcement under the AWA is that it is rigid and mechanistic.

Because of its historical roots in concern for pets, the AWA’s reach is confined to warm-blooded animals, and it contains special regulations addressed to certain animal favorites: dogs, cats, rabbits, and monkeys. Its animal experimentation regulations apply to any school or research facility that purchases or transports live animals in interstate commerce or that receives federal funding. But in fact the law has never reached the bulk of warm-blooded animals actually used in research. Concern about high regulatory costs—and about possible delay in creating guidelines for other, more popular animals—led the USDA to exclude laboratory rats and mice from its oversight from as early as 1970. In spite of lobbying efforts in the 1980s by proanimal groups, a congressional amendment to the AWA in 2002 legally formalized the agency’s longtime practice, excluding rats, mice, and birds from the definition of “animal.” [3]

In general, the law and its implementing regulations have focused on setting demanding, detailed standards for animal housing and basic standards for pain control. It supports only minimal review of the scientific merit of research protocols, but it requires researchers to make efforts to “reduce, replace, and refine.”

The self-regulatory approach to animal research regulation is embodied in the National Institutes of Health’s Guide for the Care and Use of Laboratory Animals . [4]   The Guide has existed in some version since 1963, when it was introduced as a voluntary set of professional standards for laboratory animal research. Today, the Guide’s standards are mandatory for all research facilities receiving federal funds. The Guide covers the treatment of all vertebrates, which means that, at least in federally funded research, it closes many of the gaps left open by the AWA. Not only are rats, mice, and birds covered, but also cold-blooded vertebrates like zebra fish—currently the go-to animal for laboratory studies of pain and nerve function.

The change in the Guide’s status to a rulebook has altered its content somewhat. Earlier editions’ expansive aspirational goals have given way in later editions to more readily applicable rules. There has also been considerable pressure to get the AWA’s regulatory requirements and the Guide’s standards to match, since all federally funded researchers are bound by both. Indeed, today, the two sets of standards are, if not identical, at least compatible with one another. But in general, where the AWA regulations are more rigidly prescriptive, the Guide permits lab veterinarians to use their professional judgment in applying general standards to particular species or protocols.

Clearly there is room for reform. If the AWA were amended to include rats, mice, and birds, for example, that would be a major step toward ensuring the humane treatment of all animals in public and private labs.  

Federal standards are full of specific requirements for different kinds of studies, but in general, it is fair to say that they offer the most concrete guidance on questions of animal housing and care. The regulations include detailed discussions of square footage, exercise requirements, room temperature, and more. Considerably less guidance is offered on issues of protocol evaluation and implementation of the three Rs.

Of course, this is exactly what might be expected given the incredible volume and variety of animal research in the United States. A central authority can say a lot about how to house and feed monkeys, mice, and zebra fish, and expert advice on those issues will apply to all monkeys, mice, and zebra fish in every lab, no matter what protocols they are being used for. But questions about the other possible sources of unnecessary animal suffering—the scientific justification of a given protocol, or the ways in which animal suffering connected to a given protocol might be avoided or reduced—are too numerous and varied to be answerable in advance by a central authority. With regard to those highly fact-specific questions, U.S. law relies on the expert judgment of local IACUCs.

It is no coincidence that this kind of reliance on decentralized expert committees is also the salient feature of U.S. law governing research on human subjects. The federal Common Rule, [5]  faced with a similar diversity of research protocols to evaluate, regulate, and modify, uses the same tactics as the AWA: it mandates creating research oversight committees (institutional review boards), specifies that their membership should include both relevant expertise and community representation, and empowers them to make and enforce a range of judgments about particular experimental protocols.

While the many IACUCs are expected to exercise independent judgment with regard to the scientific issues brought before them, the U.S. government does its best to inform the judgment by providing them with educational resources. The Public Health Service and the Department of Agriculture Web sites are full of guidance documents and educational resources for laboratory researchers and for IACUC members. There are documents, for example, with specific ideas about how and when to substitute lower-order animals for higher-order animals, and other documents providing up-to-date scientific news about newly developed computer models that can substitute, in some cases, for animal experimentation.

Finally, just as in the human subjects research world, federal regulations are quite commonly supplemented by private education and accreditation. Many research facilities seek accreditation by the Association for the Assessment and Accreditation of Laboratory Animal Care, a professional association of veterinarians and laboratory scientists. AAALAC provides education and does prearranged site inspections of labs once every three years. Educational and inspection standards are built largely around the requirements of the Guide , and the NIH accepts AAALAC accreditation as prima facie evidence of a facility’s compliance with the Guide’s requirements.

Toward Reform: Accountability, Uniformity, Balance

The system of decentralized oversight by local IACUCs has several obvious advantages: it permits oversight by people with knowledge of the local researchers and laboratory facilities; it allows IACUCs to develop specialized knowledge, well tailored to the research being done at their facilities; and it is likely more speedy than any alternative program of centralized governmental research oversight would be. On the other hand, the decentralization of oversight has given rise to a number of problems—which, not surprisingly, are similar to those that beset the IRB system in human subjects research.

First, there is a problem of transparency and accountability. IACUCs are for the most part fairly anonymous. Hardly anyone not directly involved in animal research knows that they exist, much less who their members are. And of course, their members are not elected or in any other way publicly accountable for the decisions they make. Most IACUC decisions do not take the form of opinions or any other form of substantive, publishable decision, but of recommendations to researchers for piecemeal alteration of protocols. A central repository of IACUC minutes, and of policies adopted by different IACUCs, might both increase accountability and stimulate new ideas by creating cross talk between IACUCs. But any such repository would have to be created with an eye toward preserving researchers’ intellectual property.

Second, decentralization almost necessarily gives rise to a lack of uniformity in decision-making and in quality of research oversight. One IACUC may conclude that a protocol involves unnecessarily harsh treatment of animals or presents an opportunity for substitution of nonanimal models; another may view the original protocol as unproblematic and requiring no amendment. A number of studies have shown that similar protocols are treated quite differently by different IACUCs. [6]  It is unclear what the implications of such findings are. Do they reveal that IACUCs have differing standards relating to animal welfare? That they judge similar protocols differently when they are presented by different researchers? Or some combination of these factors? In any case, enforced uniformity across IACUCs is a dangerous solution to propose for the problem of varying standards, in the absence of clear knowledge about whose standards are appropriate—and whose would be enforced.

A third complaint about the decentralized approach to animal-research regulation involves the perception that the U.S. government is too deferential to local IACUCs and does not take the task of auditing labs sufficiently seriously. In the early 2000s, there were some high-profile allegations made by whistleblowers from the USDA’s Animal and Plant Health Inspection Service (APHIS) that audit findings were deliberately being watered down to be less critical than the field officers originally intended them to be. [7]  U.S. audits of APHIS confirmed allegations of lax auditing in some regions of the country. [8]  The obvious reform here is to better fund and train both the regulatory overseers and those who audit their performance.

There are other important criticisms of the U.S. regulatory regime not directly connected to its choice of decentralized decision-making. First, there is the question of scientific justification for animal suffering. The AWA does not ask IACUCs to balance animal suffering against the scientific merit or promise of any given experiment. Instead, it asks IACUCs to ensure only that any given protocol has scientific merit and that any animal suffering the protocol induces is strictly necessary to that science. The result is that any study that will advance science, even in a very small way, can be used to justify tremendous amounts of animal suffering, as long as the suffering is necessary to the advance. Though they do seek to modify studies via use of the three Rs, IACUCs almost never reject protocols.

Finally, and most importantly, there is the issue of which animals are protected. As already mentioned, the hundreds of thousands of rats, mice, and birds used in private, nonfederally funded labs are not subject to any federal regulation. (Some individual states’ anticruelty statutes may apply in some cases, but there is very limited case law in the area.) Excluded, also, are cold-blooded animals. This means that there is no federal legal pressure on private firms such as drug companies to reduce or refine animal use, or to replace animals with computer or tissue models—a strategy that may be particularly feasible in studies of toxicology or drug metabolization.

Even in federally funded facilities, the living conditions of rats, mice, and birds are not subject to the USDA’s APHIS inspection; only in AAALAC-accredited facilities is there oversight beyond self-reporting, and AAALAC does scheduled inspections only once every three years. Rats and mice, it should be stressed, are the most commonly used laboratory animals. In addition, U.S. law offers no protection for invertebrate, cold-blooded animals such as cephalopods. By contrast, Europe has recently moved to protect cephalopods in light of their manifest intelligence and sentience. Nor does U.S. law prevent research on great apes, or ban (though it does regulate) the use of wild-caught animals. And the United States is one of only two governments in the world that still permits invasive research on chimpanzees, though the scope of federal funding for chimp research has recently been sharply limited. [9]  (See “Raising the Bar: The Implications of the IOM Report on the Use of Chimpanzees in Research,” in this volume.)

Clearly there is room for reform. Some needed reform involves stepping up research oversight. If the AWA were amended to include rats, mice, and birds, for example, that would be a major step toward ensuring the humane treatment of all animals in public and private labs. In addition, the inspection rate for facilities could be more frequent. Publicly funded U.S. labs are inspected by APHIS about once a year, by their own IACUCs twice a year, and by AAALAC (if they choose to be AAALAC-certified) once every three years. Compare this to the U.K. system of inspecting about once a month. Other reforms could involve improving rigid and not-terribly-useful existing regulations, like cage-size requirements currently based on animals’ body size rather than on their behavioral needs. Most significantly, the law could be reformed to permit a more explicit balancing of harms to animals (including both suffering and death) against the scientific gains at which the research aims. Empowering IACUCs to engage in such balancing is hardly radical; IRBs, for example, are already empowered to engage in such balancing in the human subjects research area, and this has not caused research to grind to a halt. Such a reform would require us to confront directly the question of how much suffering humans can impose on other species in return for small but real gains in knowledge.

Finally, a great deal can be accomplished even within an unchanged legal regime. The most urgent need is for more to be done to implement the three Rs. The familiar calls for better education about replacement techniques and more aggressive IACUC intervention on behalf of reduction and refinement are, of course, well justified. But even more dramatic reduction might be achieved if the goal of reduction were pursued not only within but also across protocols. There might be significant gains from putting animal-sharing procedures in place at the institutional level. At the moment, animals are commonly euthanized whenever the particular research project they’re involved in comes to an end, without regard to the animal’s age or health status. If a protocol involves attempts to breed, for example, mice with particular genetic traits, the pups born without those traits are routinely euthanized. If research facilities could work with researchers to use healthy animals from one study in another, rather than default to their euthanization, then fewer animals would need to be bred for suffering.

Stephen R. Latham is director of the Interdisciplinary Center for Bioethics at Yale University. He has published on a broad range of issues at the intersection of bioethics and law. He is a former board member of the American Society for Bioethics and Humanities, a former graduate fellow of Harvard’s Safra Center on Ethics, and a former research fellow of the University of Edinburgh’s Institute for Advanced Studies in Humanities. His current research includes a project funded by the Robert Wood Johnson Foundation to create a database of state statutes and cases criminalizing HIV exposure and a project on a legal framework for newborn whole-exome screening. 

• 1. The widely accepted “Three Rs” terminology was first introduced into the animal research literature in W.M.S. Russell and R.L. Burch, The Principals of Human Experimentation Technique (London: Methuen, 1959). ↵
• 2. A detailed account of the confluence of these two streams of regulation (to which my brief discussion here is heavily indebted) is provided by L. Carbone, What Animals Want: Expertise and Advocacy in Laboratory Animal Welfare Policy (Oxford, U.K.: Oxford University Press, 2004), p. 34ff. ↵
• 3. Wild-caught rats and mice are included in the regulations. For more detail, see Carbone, What Animals Want , p. 69ff. ↵
• 4. National Research Council, Guide for the Care and Use of Laboratory Animals , 8th ed.(Washington, D.C.: National Academies Press, 2011). ↵
• 5. U.S. Department of Health and Human Services, 45 CFR 46. ↵
• 6. See, for example, S. Plous and H. Herzog, “Reliability of Protocol Reviews for Animals Research,” Science 293 (2001): 608-9. ↵
• 7. See, for example, the statement of Dr. Isis Johnson-Brown, USDA whistleblower, alleging regulatory inaction on her report criticizing cage conditions at the Oregon Primate Center, at http://www.all-creatures.org/saen/articles-statementofijb.html, accessed October 2, 2012. ↵
• 8. USDA Office of Inspector General, Western Region, “Audit Report: APHIS Animal Care Program Inspection and Enforcement Activities,” Report No. 33002-3-SF, September 2005, p. i, http://www.usda.gov/oig/webdocs/33002-03-SF.pdf. ↵
• 9. See Institute of Medicine, Committee on the Use of Chimpanzees in Biomedical and Behavioral Research: Assessing the Necessity (Washington, D.C.: National Academies Press, 2011); B.M. Altevogt et al., “Guiding Limited Use of Chimpanzees in Research,” Science 335 (2012): 41-42. ↵

Is animal research ethical?

Posted: by John Meredith on 16/02/22

More on these Topics:

How can it be right to use an animal for research where we could consider it unethical to use a human being? This is a fundamental question that confronts anybody who benefits from research using animals. If we claim that causing harm to animals is sometimes justifiable where it would be unacceptable to inflict a similar harm or risk on a person, then it seems we are assuming that animals must, in some sense, have less moral value. But is that a justifiable assumption, or is it just a self-serving prejudice? Are there solid rational arguments for treating humans differently from other animals, or are we simply falling back on outmoded habits of thought, a smokescreen that helps us avoid looking the ugly truth of our actions in the eye?

Moral status of animals

In the past, the moral status of animals did not merit a great deal of consideration; raising questions about whether humans were entitled to exploit animals would have struck most people as quaint or absurd. The great moral philosopher Rene Descartes, for example, the man famous for the phrase  cogito ergo sum  - ‘I think therefore I am’ - believed that animals had no inner life at all, that they were essentially as lifeless as clockwork dolls, incapable of emotion, self-awareness, or even feeling pain.  

Such ideas seem laughable to us now. We take it for granted that most animals experience pain and many have complex emotional lives that can depend on relationships with other animals and which can deliver feelings of pleasure and satisfaction. Since Descartes’ day, the growing study of animal behaviour makes this seem obvious, and cleverly designed experiments have confirmed what has been learned from observation, forcing us to acknowledge that sentience – inner life – exists in a great number of other species and sometimes at a very high level. 

But what implications does all this have for the moral consideration of animals? How should it affect the way we treat them? Philosopher Peter Singer, whose book  Animal Liberation  transformed the public debate on animal welfare, believes it should have deep and wide-reaching consequences. Singer argues that it is wrong to inflict harm on a person not because of any cosmic or biblical law about harm but because it is against that person’s interests as they themselves understand them. Considering moral questions in that light, he argues, explodes any idea that we can justify distinctions between individuals based on their sex or race, distinctions that have been passionately defended over many centuries. There are many differences between people of all kinds including, of course, both sexes, but they all have interests that are alike: an interest in avoiding pain or hunger for example. There is no rational basis for preferring the interests of any particular individual, or people of one race or sex class over those of another, that is simply racism and sexism. This is an idea has become widely accepted, if only recently, and it doesn’t seem particularly radical to us today, but Singer takes the idea a step further. 

If there is no non-arbitrary reason to prefer the interests of one human animal over another, how can there be any good reason to prefer the interests of a human animal over a non-human animal? Claims that humans are of special moral interest because of their intelligence or capacity for language or any of the many other things that have been suggested cut no ice.  A less intelligent human has as much interest in avoiding pain as a mathematical genius does, and the same goes for a dog, or a mouse, or a fish. To deny this, says Singer is to make a moral mistake akin to sexism or racism and he calls this way of thinking  speciesism .

One objection to the argument from speciesism is that it implies that there can never be a reason to prefer the welfare of a human being over any other animal where considerations of interest are the same. This strikes most people as counter-intuitive to say the least. Jean Kazez, philosopher and animal rights activist, suggests a thought experiment. Imagine a dedicated vegan responsible for the care of ten young children. It so happens that famine strikes and the children are all in danger of starvation except that our vegan carer owns a cow. Would it be morally acceptable for the vegan to stick by her principles and refuse to slaughter the cow to save the children? If the answer is no, then there seems to be some problem with the speciesist position. It would probably not be considered acceptable to slaughter one of the children to feed the others, after all. So, our intuition is that there must be some foundation for our moral preference for a human over an animal, at least in some extreme conditions. Perhaps the intuition is that there is moral value in feelings of kinship because this is a necessary feeling in order to be a fully healthy human, to flourish as a human being. If that is the case, then, kinship, for humans, is a kind of interest in the Singer sense and one that overrides other interests. That may be why we don’t find it reprehensible when a mother prefers the welfare of her child over that of another.

The moral value of ‘kinship’ overrides speciesism

If kinship carries moral weight, then the speciesist argument loses ground and a possible justification for preferring animals over human beings in research emerges.  Medical research is an attempt to save human lives and reduce human suffering (it has similar benefits for animal as well, of course, but we can set that aside for now, for the sake of simplicity). If, as scientists argue, this can only be achieved with the use of an animal model, then we are morally entitled to prefer the use of a non-human animal, so long as kinship has the moral value we are claiming for it and the suffering and distress of the animals is minimised as much as possible.

But what if this is all just a complicated exercise in justifying what we want to do anyway, what if our moral intuitions are just wrong? It is easy to imagine a Singerian arguing, in the case of our starving children and vegan nanny, that the cow has as much moral standing as any of the others: it has the same interest in living and not suffering the pain of hunger as the others and, what’s more, it may be better able to survive the famine given its ability to eat vegetation that cannot sustain humans. In that case, it seems the advocate of speciesism must argue that they all should starve together in the interests of admirable intellectual rigour, even if it feels a little hard on the children.

Using utility to resolve moral conflicts

As usual, though, the situation is more complicated. Peter Singer and his followers recognise that there is often a conflict of moral interests and so we need a framework for finding a resolution. This framework should not be  ad hoc or arbitrary or based on scripture or any other culturally specific text or tradition but should be rational. Within Singer’s argument the rational moral grounding is provided by utilitarianism the ethical doctrine first proposed by Jeremy Bentham in the 19th century. Utilitarianism argues that when two actions are in conflict, the morally correct one is the one that delivers the most happiness for the largest number (Bentham called this ‘utility’ for obscure reasons). In other words, the morality of an action is decided by its consequences, not by the intentions of the actor or anything else. Applied to the problem of our starving infants and their increasingly paranoid cow, a utilitarian might argue that killing the cow is justified despite it having a similar interest in living to the children because the slaughter would maximise future happiness (utility). If they all die, happiness would be at zero, and if a child was sacrificed to save the others, that would reduce overall happiness because of the distress of the survivors at their loss, the suffering endured by the child selected to die, and the indifference of the cow. 

How do you measure happiness?

Problems with utilitarian ways of thinking immediately suggest themselves: how can happiness be measured? How can the ‘happiness’ of a mouse, for example, be weighed against a person, or any other animal? Must we consider a well-intentioned action that has bad outcomes immoral instead of just unfortunate? The literature goes into all these problems and more at great depth, but for our purposes, it is at least clear that a utilitarian moral framework allows for the use of research animals in some circumstances. The human happiness delivered by a successful medical treatment can be great and long lasting while any pain or distress caused to the experimental animals is kept to a minimum and is of very limited duration. In the utilitarian scales, this tips firmly towards an ethical justification of animal research. It is a surprise to many people that Peter Singer, the father of the modern animal rights movement, comes to the same conclusion, although he argues for stricter controls and more work to reduce and mitigate the use of animals. Even without appealing to concepts such as kinship, in other words, the concept of speciesism, perhaps the most formidable intellectual weapon aimed against animal research by protest groups, does not carry the day. It is perfectly possible to allow the moral value of an animal’s interests and still justify its use in research – even if that research causes the animal harm or distress – so long as the future outcomes maximise happiness. 

Animal rights arguments

The only significant ethical argument against animal research that remains is based on the idea of rights. Just as humans have inalienable rights, the argument goes, so do animals. According to this view, the use of animals for research can never be justified for exactly the same reasons that we cannot justify using humans. But argument from rights has many more problems than argument from interests: from where are rights derived? What specific rights do animals have? Should rights be protected even when this is damaging to the welfare of the animal? This last point is perhaps the most salient. If we allow an animal has a right to its freedom, say, not to be kept in captivity (one of the key rights usually claimed by activists), then we are not only committed to ending all ownership of animals, but to the immediate release of all domestic animals into the wild even if that were to the detriment of the animals’ welfare as it surely would be. The problems mount at every step. How can it be possible to reconcile a vole’s right to life with a falcon’s right to eat? What possible mechanism could be constructed to resolve such conflicts and how much irreparable harm to natural ecosystems would follow if we built one? Without answers to questions like this it is hard to see animal rights arguments as much more than rhetoric.

Maximising future happiness and minimising present suffering is enough for an ethical justification of animal research

The case for ethical animal research, then, does not need as much building as it might at first appear. None of the major philosophical arguments for animal welfare exclude the possibility of ethical animal research. The harm that is done to animals in well-regulated research environments serves a higher moral purpose: the reduction of death and suffering by disease and other disorders. Of course, this is only true if pain, suffering and distress, are minimised – as they are through animal welfare regulations in the UK and EU for example. These regulations also require the application of the principles of the 3Rs – but it is quite obvious, all other things being equal, that the use of a mouse in an investigation into cancer development, for example, will create less suffering than using a person for the same purposes. 

So, a utilitarian calculation of maximising future happiness and minimising present suffering is enough for an ethical justification of animal research even for tough minded opponents of animal exploitation such as Professor Singer. But maybe justification is the wrong word. 

Are we not morally obliged to use animals in research?

If, as the biological sciences are almost unanimous in claiming, we cannot have new medicines without some animal research, and if there are hundreds of devastating human illnesses that will continue to cause misery, pain, and heartache without those new treatments, should we not think of animal research as a moral obligation instead? It is difficult science to do, both technically and emotionally, but if we choose not to carry it out, we are effectively choosing to allow human suffering to continue in the future that our efforts today have the potential to reduce or eliminate. We don’t know which suffering we will be successful in mitigating when, but we can be certain that progress is being made. Remove animal research and we don’t not remove suffering, we simply transfer it from the animals now (where it is carefully controlled and minimised, very often to nothing) to future humans. That is the heart of the ethical case for animal research and one that needs to be better addressed by those who oppose it.

Last edited: 7 April 2022 12:16

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Will we ever… eliminate animal experimentation?

Arguably one of the most heated debates in science, efforts to reduce the number of animals used in studies face many barriers, says Alla Katsnelson.

One of the most, if not the most, contentious issues in science is the use of animals in research. Scientists experiment on animals for a host of different reasons, including basic research to explore how organisms function, investigating potential treatments for human disease, and safety and quality control testing of drugs, devices and other products. Its proponents point to the long list of medical advances made possible with the help of animal research. Opponents believe it is cruel and meaningless, as observations in animals often do not translate directly to humans.

In 1959, William Russell and Rex Burch proposed their “3Rs” guidelines for making the use of animals in scientific research more humane: restrict the use of animals; refine experiments to minimise distress; and replace tests with alternative techniques. Over the course of five decades their guidelines have become widely accepted worldwide, and while the reliability of published reports on the numbers used varies, they do at least provide a snapshot of historical trends. Around 29 million animals per year are currently used in experiments in the US and European Union countries. (Rats and mice make up around 80% of the total.) This is less than half the total in the mid-1970s – a significant drop, but one that has plateaued in the last decade.

“In the late 1980s, people thought animal research was singing its swan song,” says Larry Carbone, a senior veterinarian at the University of California in San Francisco. Fresh out of veterinary school in 1987, Carbone landed a job as an animal vet at Cornell University, in New York State. At that time the numbers of animals being used in experiments and testing was on the decline: the campus was building a new multi-storey biotechnology facility, with just three rooms containing animal breeding and living facilities.

But then came the development of tools that could selectively modify individual genes in mice. This proved to be such a powerful and popular technique that the decreasing trend in animal use ground to a halt.

Now, a raft of novel experimental techniques may help to push numbers down again. Improvements in imaging methods that offer a peek inside the bodies of animals allow scientists to get more and better data from each experiment than before. For example, researchers previously had to cull multiple mice at different stages of tumour development, but now they can non-invasively watch the disease unfold in a single living animal using a fluorescent dye. Similarly, as brain-imaging techniques become more advanced, some questions that are now addressed with experiments in monkeys might be better answered by peering into the human brain. “My prediction is that human volunteers will be able to replace monkeys more and more in the next 10-20 years,” says Carbone.

Meanwhile in vitro advances are also pointing towards reliable alternative methods. One such advance is the ability to re-program human skin cells into a primordial, stem cell-like state. These “induced pluripotent cells” could be converted into any specialised cell in the body, like liver or kidney cells , and these could be generated from people with a particular illness, giving researchers a potent and patient-specific model of that disease in a dish. Lab-on-a-chip technologies – and perhaps one day, lab-grown organs – could also provide increasingly sophisticated ways to identify disease mechanisms or test prospective medicines.

Finding alternatives

Trends also show that some sectors are doing more than others to reduce animal use. Some believe technological advances will one day make animal studies unnecessary, while others argue that “non-living” models will never be capable of reliably replicating all of the uses of laboratory mice and other creatures.

When many people think about animal testing, they imagine rows of rodent cages in a pharmaceutical company lab. But according to data from European Union countries, the pharmaceutical sector uses almost half the number of animals that academic labs do, and animal use in drug development dropped significantly between 2005 and 2008 – the most recent statistics available. There are two reasons for this, says Thomas Hartung, Director of the Center for Alternatives to Animal Testing at Johns Hopkins University, in Baltimore, Maryland. First, drugs are increasingly designed to target specific molecular mechanisms, and these are best identified in culture dishes rather than live animals. Second, conducting experiments in 1,536-well cell culture dishes is vastly less expensive than in animals, so companies are motivated to use alternatives whenever they are available.

In the US and the EU, a drug’s efficacy and safety must be tested in animals before it enters human testing, though a 2010 directive from the EU calls for alternatives to be used when possible. Jan Ottesen, vice president of lab animal science at Danish company Novo Nordisk, which makes insulin and other drugs for diabetes and haemophilia, says his company actively seeks out tests that can replace animal use without compromising patient safety. Novo Nordisk decided 15 years ago to replace animal tests with cell cultures to verify the quality of each batch of drugs before it goes to market. The company had to provide the authorities with data proving that other tests worked just as well. It took until 2011 for the company to complete the switch. 

However, for some types of experiments there are no equivalent non-animal options, says Ottesen. For example, in searching for new drugs that decrease joint pain due to arthritis, you need a model that mimics the human condition. The important thing, he stressed, is to set up the experiment so as to avoid unnecessary pain. For safety and toxicological testing of drugs, he adds, “I cannot see for the foreseeable future how we can completely avoid it. Having said that, all the replacements that can be implemented should be implemented."

Under pressure

Safety testing of substances other than human and veterinary drugs, such as cosmetics, toiletries, household cleaning products and industrial chemicals might be a different story. Currently, says Hartung, such tests are outdated and inaccurate, with toxicity in rodents predicting problems in humans just 43% of the time. Meanwhile, tens of thousands of these substances have undergone no toxicity testing at all.

Addressing this gap with animal studies alone would be expensive and impractical. An overhaul of chemical safety regulations in the EU called REACH and a toxicology modernisation initiative led by the US National Institutes of Health, are driving the search for alternatives.

Hartung believes that with enough investment and coordination, animal tests on products in this category can be replaced completely. He is leading the Human Toxome Project, an initiative that aims to map the ways substances disrupt hormones and endanger health, as well as to develop advanced, non-animal lab tests for toxicity testing. It’s slow going, Hartung concedes. “We don’t have human data to compare with, or really high-quality animal data,” he says, adding that this makes it tough to evaluate the quality of the tests.

Meanwhile, almost four in ten animals are used in basic, as opposed to applied, biological research – and this proportion is growing. Sarah Wolfensohn, a veterinary surgeon who heads Seventeen Eighty Nine, a consultancy advising researchers on animal welfare, based in Swindon, UK, says this is in part because a lot of this type of work is carried out in academia where the financial and performance pressures that motivate interest in non-animal-based techniques are weaker than in the commercial sector.

Other factors play a role too, she says. "For example, if a senior professor in academia has spent his entire career developing experimental techniques on monkeys' brains and young researchers now tell him 'actually we don't need to do this, we can do it on a computer', it undermines his approach."

But just as important as reducing the numbers of animals used, adds Wolfensohn, is “to make sure they are being used in the best way and that their welfare is maximised, so as to get the best quality results, to make sure they are not wasted.”

Overall, pressure to limit the use of animals in research – either for financial, scientific or moral reasons – is rising. Meanwhile, the use of animals in many areas of life-science research is on the decline, experts note, even if genetic work in mice is still keeping numbers up. “I think this is temporary,” says Andrew Rowan, President and Chief Executive Officer of animal protection group Humane Society International. “I think it is going to start going down again as we improve our technologies.” How soon this might happen is too difficult to tell.

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What is animal testing?

An introduction to animal experiments

What are animal experiments?

An animal test is any scientific experiment or test in which a live animal is forced to undergo something that is likely to cause them pain, suffering, distress or lasting harm. 

Animal experiments are not the same as taking your companion animal to the vet. Animals used in laboratories are deliberately harmed, not for their own good, and are usually killed at the end of the experiment.

Animal experiments include:

• injecting or force feeding animals with potentially harmful substances
• surgically removing animals’ organs or tissues to deliberately cause damage
• forcing animals to inhale toxic gases
• subjecting animals to frightening situations to create anxiety and depression.

Some experiments require the animal to die as part of the test. For example, regulatory tests for botox, vaccines and some tests for chemical safety are essentially variations of the cruel Lethal Dose 50 test in which 50% of the animals die or are killed just before the point of death.

Which animals are used?

A surprisingly, large range of animal species are regularly used in experiments, including wild animals.

Only vertebrate animals (mammals, birds, fish and amphibians) and some invertebrates such as octopuses are defined as “animals” by European legislation governing animal experiments.  Shockingly, in the USA rats, mice, fish, amphibians and birds are not defined as animals under animal experiment regulations. That means no legal permission to experiment on them is needed and they are not included in any statistics.

Animals used in experiments are usually bred for this purpose by the laboratory or in breeding facilities. It’s a cruel, multi-million dollar industry. We believe that all animals are equally important. A dog bred for research is still a dog who could otherwise live a happy life in a loving home.

Some monkeys are still trapped in the wild in Africa, Asia and South America to be used in experiments or imprisoned in breeding facilities. Their children are exported to laboratories around the world. The use of wild-caught monkeys in experiments is generally banned in Europe but is allowed elsewhere.

Horses and other animals such as cows, sheep and pigs are often supplied by dealers and may originate from racing stables or farms for use in animal experiments. The rules preventing the use of stray companion animals like dogs and cats vary from country to country.

Wild animals can be used in trapping and monitoring experiments in the wild, or they may be captured and brought into a laboratory setting for more invasive research, sometimes in the name of conservation.

What are laboratories like?

Laboratories are no place for any animal. They are typically sterile, indoor environments in which the animals are forced to live in cages, pens or Perspex boxes – denied complete freedom of movement and control over their lives. Some animals in laboratories are confined on their own, without the companionship of others.

Our investigations show time and time again that, despite claims by the animal research community, life inside a laboratory is no life at all.

The science relating to animal experiments can be extremely complicated and views often differ. What appears on this website represents Cruelty Free International expert opinion, based on a thorough assessment of the evidence.

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• J Prev Med Hyg
• v.63(2 Suppl 3); 2022 Jun

Ethical considerations regarding animal experimentation

Aysha karim kiani.

1 Allama Iqbal Open University, Islamabad, Pakistan

2 MAGI EUREGIO, Bolzano, Italy

DEREK PHEBY

3 Society and Health, Buckinghamshire New University, High Wycombe, UK

GARY HENEHAN

4 School of Food Science and Environmental Health, Technological University of Dublin, Dublin, Ireland

RICHARD BROWN

5 Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada

PAUL SIEVING

6 Department of Ophthalmology, Center for Ocular Regenerative Therapy, School of Medicine, University of California at Davis, Sacramento, CA, USA

PETER SYKORA

7 Department of Philosophy and Applied Philosophy, University of St. Cyril and Methodius, Trnava, Slovakia

ROBERT MARKS

8 Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

BENEDETTO FALSINI

9 Institute of Ophthalmology, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy

NATALE CAPODICASA

10 MAGI BALKANS, Tirana, Albania

STANISLAV MIERTUS

11 Department of Biotechnology, University of SS. Cyril and Methodius, Trnava, Slovakia

12 International Centre for Applied Research and Sustainable Technology, Bratislava, Slovakia

LORENZO LORUSSO

13 UOC Neurology and Stroke Unit, ASST Lecco, Merate, Italy

DANIELE DONDOSSOLA

14 Center for Preclincal Research and General and Liver Transplant Surgery Unit, Fondazione IRCCS Ca‘ Granda Ospedale Maggiore Policlinico, Milan, Italy

15 Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy

GIANLUCA MARTINO TARTAGLIA

16 Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy

17 UOC Maxillo-Facial Surgery and Dentistry, Fondazione IRCCS Ca Granda, Ospedale Maggiore Policlinico, Milan, Italy

MAHMUT CERKEZ ERGOREN

18 Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus

MUNIS DUNDAR

19 Department of Medical Genetics, Erciyes University Medical Faculty, Kayseri, Turkey

SANDRO MICHELINI

20 Vascular Diagnostics and Rehabilitation Service, Marino Hospital, ASL Roma 6, Marino, Italy

DANIELE MALACARNE

21 MAGI’S LAB, Rovereto (TN), Italy

GABRIELE BONETTI

Astrit dautaj, kevin donato, maria chiara medori, tommaso beccari.

22 Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy

MICHELE SAMAJA

23 MAGI GROUP, San Felice del Benaco (BS), Italy

STEPHEN THADDEUS CONNELLY

24 San Francisco Veterans Affairs Health Care System, University of California, San Francisco, CA, USA

DONALD MARTIN

25 Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC-IMAG, SyNaBi, Grenoble, France

ASSUNTA MORRESI

26 Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy

ARIOLA BACU

27 Department of Biotechnology, University of Tirana, Tirana, Albania

KAREN L. HERBST

28 Total Lipedema Care, Beverly Hills California and Tucson Arizona, USA

MYKHAYLO KAPUSTIN

29 Federation of the Jewish Communities of Slovakia

LIBORIO STUPPIA

30 Department of Psychological, Health and Territorial Sciences, School of Medicine and Health Sciences, University "G. d'Annunzio", Chieti, Italy

LUDOVICA LUMER

31 Department of Anatomy and Developmental Biology, University College London, London, UK

GIAMPIETRO FARRONATO

Matteo bertelli.

32 MAGISNAT, Peachtree Corners (GA), USA

Animal experimentation is widely used around the world for the identification of the root causes of various diseases in humans and animals and for exploring treatment options. Among the several animal species, rats, mice and purpose-bred birds comprise almost 90% of the animals that are used for research purpose. However, growing awareness of the sentience of animals and their experience of pain and suffering has led to strong opposition to animal research among many scientists and the general public. In addition, the usefulness of extrapolating animal data to humans has been questioned. This has led to Ethical Committees’ adoption of the ‘four Rs’ principles (Reduction, Refinement, Replacement and Responsibility) as a guide when making decisions regarding animal experimentation. Some of the essential considerations for humane animal experimentation are presented in this review along with the requirement for investigator training. Due to the ethical issues surrounding the use of animals in experimentation, their use is declining in those research areas where alternative in vitro or in silico methods are available. However, so far it has not been possible to dispense with experimental animals completely and further research is needed to provide a road map to robust alternatives before their use can be fully discontinued.

How to cite this article: Kiani AK, Pheby D, Henehan G, Brown R, Sieving P, Sykora P, Marks R, Falsini B, Capodicasa N, Miertus S, Lorusso L, Dondossola D, Tartaglia GM, Ergoren MC, Dundar M, Michelini S, Malacarne D, Bonetti G, Dautaj A, Donato K, Medori MC, Beccari T, Samaja M, Connelly ST, Martin D, Morresi A, Bacu A, Herbst KL, Kapustin M, Stuppia L, Lumer L, Farronato G, Bertelli M. Ethical considerations regarding animal experimentation. J Prev Med Hyg 2022;63(suppl.3):E255-E266. https://doi.org/10.15167/2421-4248/jpmh2022.63.2S3.2768

Introduction

Animal model-based research has been performed for a very long time. Ever since the 5 th century B.C., reports of experiments involving animals have been documented, but an increase in the frequency of their utilization has been observed since the 19 th century [ 1 ]. Most institutions for medical research around the world use non-human animals as experimental subjects [ 2 ]. Such animals might be used for research experimentations to gain a better understanding of human diseases or for exploring potential treatment options [ 2 ]. Even those animals that are evolutionarily quite distant from humans, such as Drosophila melanogaster , Zebrafish ( Danio rerio ) and Caenorhabditis elegans , share physiological and genetic similarities with human beings [ 2 ]; therefore animal experimentation can be of great help for the advancement of medical science [ 2 ].

For animal experimentation, the major assumption is that the animal research will be of benefit to humans. There are many reasons that highlight the significance of animal use in biomedical research. One of the major reasons is that animals and humans share the same biological processes. In addition, vertebrates have many anatomical similarities (all vertebrates have lungs, a heart, kidneys, liver and other organs) [ 3 ]. Therefore, these similarities make certain animals more suitable for experiments and for providing basic training to young researchers and students in different fields of biological and biomedical sciences [ 3 ]. Certain animals are susceptible to various health problems that are similar to human diseases such as diabetes, cancer and heart disease [ 4 ]. Furthermore, there are genetically modified animals that are used to obtain pathological phenotypes [ 5 ]. A significant benefit of animal experimentation is that test species can be chosen that have a much shorter life cycle than humans. Therefore, animal models can be studied throughout their life span and for several successive generations, an essential element for the understanding of disease progression along with its interaction with the whole organism throughout its lifetime [ 6 ].

Animal models often play a critical role in helping researchers who are exploring the efficacy and safety of potential medical treatments and drugs. They help to identify any dangerous or undesired side effects, such as birth defects, infertility, toxicity, liver damage or any potential carcinogenic effects [ 7 ]. Currently, U.S. Federal law, for example, requires that non-human animal research is used to demonstrate the efficacy and safety of any new treatment options before proceeding to trials on humans [ 8 ]. Of course, it is not only humans benefit from this research and testing, since many of the drugs and treatments that are developed for humans are routinely used in veterinary clinics, which help animals live longer and healthier lives [ 4 ].

COVID-19 AND THE NEED FOR ANIMAL MODELS

When COVID-19 struck, there was a desperate need for research on the disease, its effects on the brain and body and on the development of new treatments for patients with the disease. Early in the disease it was noticed that those with the disease suffered a loss of smell and taste, as well as neurological and psychiatric symptoms, some of which lasted long after the patients had “survived” the disease [ 9-15 ]. As soon as the pandemic started, there was a search for appropriate animal models in which to study this unknown disease [ 16 , 17 ]. While genetically modified mice and rats are the basic animal models for neurological and immunological research [ 18 , 19 ] the need to understand COVID-19 led to a range of animal models; from fruit flies [ 20 ] and Zebrafish [ 21 ] to large mammals [ 22 , 23 ] and primates [ 24 , 25 ]. And it was just not one animal model that was needed, but many, because different aspects of the disease are best studied in different animal models [ 16 , 25 , 26 ]. There is also a need to study the transmission pathways of the zoonosis: where does it come from, what are the animal hosts and how is it transferred to humans [ 27 ]?

There has been a need for animal models for understanding the pathophysiology of COVID-19 [ 28 ], for studying the mechanisms of transmission of the disease [ 16 ], for studying its neurobiology [ 29 , 30 ] and for developing new vaccines [ 31 ]. The sudden onset of the COVID-19 pandemic has highlighted the fact that animal research is necessary, and that the curtailment of such research has serious consequences for the health of both humans and animals, both wild and domestic [ 32 ] As highlighted by Adhikary et al. [ 22 ] and Genzel et al. [ 33 ] the coronavirus has made clear the necessity for animal research and the danger in surviving future such pandemics if animal research is not fully supported. Genzel et al. [ 33 ], in particular, take issue with the proposal for a European ban on animal testing. Finally, there is a danger in bypassing animal research in developing new vaccines for diseases such as COVID-19 [ 34 ]. The purpose of this paper is to show that, while animal research is necessary for the health of both humans and animals, there is a need to carry out such experimentation in a controlled and humane manner. The use of alternatives to animal research such as cultured human cells and computer modeling may be a useful adjunct to animal studies but will require that such methods are more readily accessible to researchers and are not a replacement for animal experimentation.

Pros and cons of animal experimentation

Arguments against animal experimentation.

A fundamental question surrounding this debate is to ask whether it is appropriate to use animals for medical research. Is our acceptance that animals have a morally lower value or standard of life just a case of speciesism [ 35 ]? Nowadays, most people agree that animals have a moral status and that needlessly hurting or abusing pets or other animals is unacceptable. This represents something of a change from the historical point of view where animals did not have any moral status and the treatment of animals was mostly subservient to maintaining the health and dignity of humans [ 36 ].

Animal rights advocates strongly argue that the moral status of non-human animals is similar to that of humans, and that animals are entitled to equality of treatment. In this view, animals should be treated with the same level of respect as humans, and no one should have the right to force them into any service or to kill them or use them for their own goals. One aspect of this argument claims that moral status depends upon the capacity to suffer or enjoy life [ 37 ].

In terms of suffering and the capacity of enjoying life, many animals are not very different from human beings, as they can feel pain and experience pleasure [ 38 ]. Hence, they should be given the same moral status as humans and deserve equivalent treatment. Supporters of this argument point out that according animals a lower moral status than humans is a type of prejudice known as “speciesism” [ 38 ]. Among humans, it is widely accepted that being a part of a specific race or of a specific gender does not provide the right to ascribe a lower moral status to the outsiders. Many advocates of animal rights deploy the same argument, that being human does not give us sufficient grounds declare animals as being morally less significant [ 36 ].

ARGUMENTS IN FAVOR OF ANIMAL EXPERIMENTATION

Those who support animal experimentation have frequently made the argument that animals cannot be elevated to be seen as morally equal to humans [ 39 ]. Their main argument is that the use of the terms “moral status” or “morality” is debatable. They emphasize that we must not make the error of defining a quality or capacity associated with an animal by using the same adjectives used for humans [ 39 ]. Since, for the most part, animals do not possess humans’ cognitive capabilities and lack full autonomy (animals do not appear to rationally pursue specific goals in life), it is argued that therefore, they cannot be included in the moral community [ 39 ]. It follows from this line of argument that, if animals do not possess the same rights as human beings, their use in research experimentation can be considered appropriate [ 40 ]. The European and the American legislation support this kind of approach as much as their welfare is respected.

Another aspect of this argument is that the benefits to human beings of animal experimentation compensate for the harm caused to animals by these experiments.

In other words, animal harm is morally insignificant compared to the potential benefits to humans. Essentially, supporters of animal experimentation claim that human beings have a higher moral status than animals and that animals lack certain fundamental rights accorded to humans. The potential violations of animal rights during animal research are, in this way, justified by the greater benefits to mankind [ 40 , 41 ]. A way to evaluate when the experiments are morally justified was published in 1986 by Bateson, which developed the Bateson’s Cube [ 42 ]. The Cube has three axes: suffering, certainty of benefit and quality of research. If the research is high-quality, beneficial, and not inflicting suffering, it will be acceptable. At the contrary, painful, low-quality research with lower likelihood of success will not be acceptable [ 42 , 43 ].

Impact of experimentations on animals

Ability to feel pain and distress.

Like humans, animal have certain physical as well as psychological characteristics that make their use for experimentation controversial [ 44 ].

In the last few decades, many studies have increased knowledge of animal awareness and sentience: they indicate that animals have greater potential to experience damage than previously appreciated and that current rights and protections need to be reconsidered [ 45 ]. In recent times, scientists as well as ethicists have broadly acknowledged that animals can also experience distress and pain [ 46 ]. Potential sources of such harm arising from their use in research include disease, basic physiological needs deprivation and invasive procedures [ 46 ]. Moreover, social deprivation and lack of the ability to carry out their natural behaviors are other causes of animal harm [ 46 ]. Several studies have shown that, even in response to very gentle handling and management, animals can show marked alterations in their physiological and hormonal stress markers [ 47 ].

In spite of the fact that suffering and pain are personalized experiences, several multi-disciplinary studies have provided clear evidence of animals experiencing pain and distress. In particular, some animal species have the ability to express pain similarly to human due to common psychological, neuroanatomical and genetic characteristics [ 48 ]. Similarly, animals share a resemblance to humans in their developmental, genetic and environmental risk factors for psychopathology. For instance, in many species, it has been shown that fear operates within a less organized subcortical neural circuit than pain [ 49 , 50 ]. Various types of depression and anxiety disorders like posttraumatic stress disorder have also been reported in mammals [ 51 ].

PSYCHOLOGICAL CAPABILITIES OF ANIMALS

Some researchers have suggested that besides their ability to experience physical and psychological pain and distress, some animals also exhibit empathy, self-awareness and language-like capabilities. They also demonstrate tools-linked cognizance, pleasure-seeking and advanced problem-solving skills [ 52 ]. Moreover, mammals and birds exhibit playful behavior, an indicator of the capacity to experience pleasure. Other taxa such as reptiles, cephalopods and fishes have also been observed to display playful behavior, therefore the current legislation prescribes the use of environmental enrichers [ 53 ]. The presence of self-awareness ability, as assessed by mirror self-recognition, has been reported in magpies, chimpanzees and other apes, and certain cetaceans [ 54 ]. Recently, another study has revealed that crows have the ability to create and use tools that involve episodic-like memory formation and its retrieval. From these findings, it may be suggested that crows as well as related species show evidence of flexible learning strategies, causal reasoning, prospection and imagination that are similar to behavior observed in great apes [ 55 ]. In the context of resolving the ethical dilemmas about animal experimentation, these observations serve to highlight the challenges involved [ 56 , 57 ].

Ethics, principles and legislation in animal experimentation

Ethics in animal experimentation.

Legislation around animal research is based on the idea of the moral acceptability of the proposed experiments under specific conditions [ 58 ]. The significance of research ethics that ensures proper treatment of experimental animals [ 58 ]. To avoid undue suffering of animals, it is important to follow ethical considerations during animal studies [ 1 ]. It is important to provide best human care to these animals from the ethical and scientific point of view [ 1 ]. Poor animal care can lead to experimental outcomes [ 1 ]. Thus, if experimental animals mistreated, the scientific knowledge and conclusions obtained from experiments may be compromised and may be difficult to replicate, a hallmark of scientific research [ 1 ]. At present, most ethical guidelines work on the assumption that animal experimentation is justified because of the significant potential benefits to human beings. These guidelines are often permissive of animal experimentation regardless of the damage to the animal as long as human benefits are achieved [ 59 ].

PRINCIPLE OF THE 4 RS

Although animal experimentation has resulted in many discoveries and helped in the understanding numerous aspects of biological science, its use in various sectors is strictly controlled. In practice, the proposed set of animal experiments is usually considered by a multidisciplinary Ethics Committee before work can commence [ 60 ]. This committee will review the research protocol and make a judgment as to its sustainability. National and international laws govern the utilization of animal experimentation during research and these laws are mostly based on the universal doctrine presented by Russell and Burch (1959) known as principle of the 3 Rs. The 3Rs referred to are Reduction, Refinement and Replacement, and are applied to protocols surrounding the use of animals in research. Some researchers have proposed another “R”, of responsibility for the experimental animal as well as for the social and scientific status of the animal experiments [ 61 ]. Thus, animal ethics committees commonly review research projects with reference to the 4 Rs principles [ 62 ].

The first “R”, Reduction means that the experimental design is examined to ensure that researchers have reduced the number of experimental animals in a research project to the minimum required for reliable data [ 59 ]. Methods used for this purpose include improved experimental design, extensive literature search to avoid duplication of experiments [ 35 ], use of advanced imaging techniques, sharing resources and data, and appropriate statistical data analysis that reduce the number of animals needed for statistically significant results [ 2 , 63 ].

The second “R”, Refinement involves improvements in procedure that minimize the harmful effects of the proposed experiments on the animals involved, such as reducing pain, distress and suffering in a manner that leads to a general improvement in animal welfare. This might include for example improved living conditions for research animals, proper training of people handling animals, application of anesthesia and analgesia when required and the need for euthanasia of the animals at the end of the experiment to curtail their suffering [ 63 ].

The third “R”, Replacement refers to approaches that replace or avoid the use of experimental animals altogether. These approaches involve use of in silico methods/computerized techniques/software and in vitro methods like cell and tissue culture testing, as well as relative replacement methods by use of invertebrates like nematode worms, fruit flies and microorganisms in place of vertebrates and higher animals [ 1 ]. Examples of proper application of these first “3R2 principles are the use of alternative sources of blood, the exploitation of commercially used animals for scientific research, a proper training without use of animals and the use of specimen from previous experiments for further researches [ 64-67 ].

The fourth “R”, Responsibility refers to concerns around promoting animal welfare by improvements in experimental animals’ social life, development of advanced scientific methods for objectively determining sentience, consciousness, experience of pain and intelligence in the animal kingdom, as well as effective involvement in the professionalization of the public discussion on animal ethics [ 68 ].

OTHER ASPECTS OF ANIMAL RESEARCH ETHICS

Other research ethics considerations include having a clear rationale and reasoning for the use of animals in a research project. Researchers must have reasonable expectation of generating useful data from the proposed experiment. Moreover, the research study should be designed in such a way that it should involve the lowest possible sample size of experimental animals while producing statistically significant results [ 35 ].

All individual researchers that handle experimental animals should be properly trained for handling the particular species involved in the research study. The animal’s pain, suffering and discomfort should be minimized [ 69 ]. Animals should be given proper anesthesia when required and surgical procedures should not be repeated on same animal whenever possible [ 69 ]. The procedure of humane handling and care of experimental animals should be explicitly detailed in the research study protocol. Moreover, whenever required, aseptic techniques should be properly followed [ 70 ]. During the research, anesthetization and surgical procedures on experimental animals should only be performed by professionally skilled individuals [ 69 ].

The Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines that are issued by the National Center for the Replacement, Refinement, and Reduction of Animals in Research (NC3Rs) are designed to improve the documentation surrounding research involving experimental animals [ 70 ]. The checklist provided includes the information required in the various sections of the manuscript i.e. study design, ethical statements, experimental procedures, experimental animals and their housing and husbandry, and more [ 70 ].

It is critical to follow the highest ethical standards while performing animal experiments. Indeed, most of the journals refuse to publish any research data that lack proper ethical considerations [ 35 ].

INVESTIGATORS’ ETHICS

Since animals have sensitivity level similar to the human beings in terms of pain, anguish, survival instinct and memory, it is the responsibility of the investigator to closely monitor the animals that are used and identify any sign of distress [ 71 ]. No justification can rationalize the absence of anesthesia or analgesia in animals that undergo invasive surgery during the research [ 72 ]. Investigators are also responsible for giving high-quality care to the experimental animals, including the supply of a nutritious diet, easy water access, prevention of and relief from any pain, disease and injury, and appropriate housing facilities for the animal species [ 73 ]. A research experiment is not permitted if the damage caused to the animal exceeds the value of knowledge gained by that experiment. No scientific advancement based on the destruction and sufferings of another living being could be justified. Besides ensuring the welfare of animals involved, investigators must also follow the applicable legislation [ 74 , 75 ].

To promote the comfort of experimental animals in England, an animal protection society named: ‘The Society for the Preservation of Cruelty to Animals’ (now the Royal Society for the Prevention of Cruelty to Animals) was established (1824) that aims to prevent cruelty to animal [ 76 ].

ANIMAL WELFARE LAWS

Legislation for animal protection during research has long been established. In 1876 the British Parliament sanctioned the ‘Cruelty to Animals Act’ for animal protection. Russell and Burch (1959) presented the ‘3 Rs’ principles: Replacement, Reduction and Refinement, for use of animals during research [ 61 ]. Almost seven years later, the U.S.A also adopted regulations for the protection of experimental animals by enacting the Laboratory Animal Welfare Act of 1966 [ 60 ]. In Brazil, the Arouca Law (Law No. 11,794/08) regulates the animal use in scientific research experiments [ 76 ].

These laws define the breeding conditions, and regulate the use of animals for scientific research and teaching purposes. Such legal provisions control the use of anesthesia, analgesia or sedation in experiments that could cause distress or pain to experimental animals [ 59 , 76 ]. These laws also stress the need for euthanasia when an experiment is finished, or even during the experiment if there is any intense suffering for the experimental animal [ 76 ].

Several national and international organizations have been established to develop alternative techniques so that animal experimentation can be avoided, such as the UK-based National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) ( www.caat.jhsph.edu ), the European Centre for the Validation of Alternative Methods (ECVAM) [ 77 ], the Universities Federation for Animal Welfare (UFAW) ( www.ufaw.org.uk ), The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) [ 78 ], and The Center for Alternatives to Animal Testing (CAAT) ( www.caat.jhsph.edu ). The Brazilian ‘Arouca Law’ also constitutes a milestone, as it has created the ‘National Council for the Control of Animal Experimentation’ (CONCEA) that deals with the legal and ethical issues related to the use of experimental animals during scientific research [ 76 ].

Although national as well as international laws and guidelines have provided basic protections for experimental animals, the current regulations have some significant discrepancies. In the U.S., the Animal Welfare Act excludes rats, mice and purpose-bred birds, even though these species comprise almost 90% of the animals that are used for research purpose [ 79 ]. On the other hand, certain cats and dogs are getting special attention along with extra protection. While the U.S. Animal Welfare Act ignores birds, mice and rats, the U.S. guidelines that control research performed using federal funding ensure protections for all vertebrates [ 79 , 80 ].

Living conditions of animals

Choice of the animal model.

Based on all the above laws and regulations and in line with the deliberations of ethical committees, every researcher must follow certain rules when dealing with animal models.

Before starting any experimental work, thorough research should be carried out during the study design phase so that the unnecessary use of experimental animals is avoided. Nevertheless, certain research studies may have compelling reasons for the use of animal models, such as the investigation of human diseases and toxicity tests. Moreover, animals are also widely used in the training of health professionals as well as in training doctors in surgical skills [ 1 , 81 ].

Researcher should be well aware of the specific traits of the animal species they intend to use in the experiment, such as its developmental stages, physiology, nutritional needs, reproductive characteristics and specific behaviors. Animal models should be selected on the basis of the study design and the biological relevance of the animal [ 1 ].

Typically, in early research, non-mammalian models are used to get rapid insights into research problems such as the identification of gene function or the recognition of novel therapeutic options. Thus, in biomedical and biological research, among the most commonly used model organisms are the Zebrafish, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans . The main advantage of these non-mammalian animal models is their prolific reproducibility along with their much shorter generation time. They can be easily grown in any laboratory setting, are less expensive than the murine animal models and are somewhat more powerful than the tissue and cell culture approaches [ 82 ].

Caenorhabditis elegans is a small-sized nematode with a short life cycle and that exists in large populations and is relatively inexpensive to cultivate. Scientists have gathered extensive knowledge of the genomics and genetics of Caenorhabditis elegans ; but Caenorhabditis elegans models, while very useful in some respects, are unable to represent all signaling pathways found in humans. Furthermore, due to its short life cycle, scientists are unable to investigate long term effects of test compounds or to analyze primary versus secondary effects [ 6 ].

Similarly, the fruit fly Drosophila melanogaster has played a key role in numerous biomedical discoveries. It is small in size, has a short life cycle and large population size, is relatively inexpensive to breed, and extensive genomics and genetics information is available [ 6 ]. However, its respiratory, cardiovascular and nervous systems differ considerably from human beings. In addition, its immune system is less developed when compared to vertebrates, which is why effectiveness of a drug in Drosophila melanogaster may not be easily extrapolated to humans [ 83 ].

The Zebrafish ( Danio rerio ) is a small freshwater teleost, with transparent embryos, providing easy access for the observation of organogenesis and its manipulation. Therefore, Zebrafish embryos are considered good animal models for different human diseases like tuberculosis and fetal alcohol syndrome and are useful as neurodevelopmental research models. However, Zebrafish has very few mutant strains available, and its genome has numerous duplicate genes making it impossible to create knockout strains, since disrupting one copy of the gene will not disrupt the second copy of that gene. This feature limits the use of Zebrafish as animal models to study human diseases. Additionally they are rather expensive, have long life cycle, and genomics and genetics studies are still in progress [ 82 , 84 ].

Thus, experimentation on these three animals might not be equivalent to experimentation on mammals. Mammalian animal model are most similar to human beings, so targeted gene replacement is possible. Traditionally, mammals like monkey and mice have been the preferred animal models for biomedical research because of their evolutionary closeness to humans. Rodents, particularly mice and rats, are the most frequently used animal models for scientific research. Rats are the most suitable animal model for the study of obesity, shock, peritonitis, sepsis, cancer, intestinal operations, spleen, gastric ulcers, mononuclear phagocytic system, organ transplantations and wound healing. Mice are more suitable for studying burns, megacolon, shock, cancer, obesity, and sepsis as mentioned previously [ 85 ].

Similarly, pigs are mostly used for stomach, liver and transplantation studies, while rabbits are suitable for the study of immunology, inflammation, vascular biology, shock, colitis and transplantations. Thus, the choice of experimental animal mainly depends upon the field of scientific research under consideration [ 1 ].

HOUSING AND ENVIRONMENTAL ENRICHMENT

Researchers should be aware of the environment and conditions in which laboratory animals are kept during research, and they also need to be familiar with the metabolism of the animals kept in vivarium, since their metabolism can easily be altered by different factors such as pain, stress, confinement, lack of sunlight, etc. Housing conditions alter animal behavior, and this can in turn affect experimental results. By contrast, handling procedures that feature environmental enrichment and enhancement help to decrease stress and positively affect the welfare of the animals and the reliability of research data [ 74 , 75 ].

In animals, distress- and agony-causing factors should be controlled or eliminated to overcome any interference with data collection as well as with interpretation of the results, since impaired animal welfare leads to more animal usage during experiment, decreased reliability and increased discrepancies in results along with the unnecessary consumption of animal lives [ 86 ].

To reduce the variation or discrepancies in experimental data caused by various environmental factors, experimental animals must be kept in an appropriate and safe place. In addition, it is necessary to keep all variables like humidity, airflow and temperature at levels suitable for those species, as any abrupt variation in these factors could cause stress, reduced resistance and increased susceptibility to infections [ 74 ].

The space allotted to experimental animals should permit them free movement, proper sleep and where feasible allow for interaction with other animals of the same species. Mice and rats are quite sociable animals and must, therefore, be housed in groups for the expression of their normal behavior. Usually, laboratory cages are not appropriate for the behavioral needs of the animals. Therefore, environmental enrichment is an important feature for the expression of their natural behavior that will subsequently affect their defense mechanisms and physiology [ 87 ].

The features of environmental enrichment must satisfy the animals’ sense of curiosity, offer them fun activities, and also permit them to fulfill their behavioral and physiological needs. These needs include exploring, hiding, building nests and gnawing. For this purpose, different things can be used in their environment, such as PVC tubes, cardboard, igloos, paper towel, cotton, disposable masks and paper strips [ 87 ].

The environment used for housing of animals must be continuously controlled by appropriate disinfection, hygiene protocols, sterilization and sanitation processes. These steps lead to a reduction in the occurrence of various infectious agents that often found in vivarium, such as Sendai virus, cestoda and Mycoplasma pulmonis [ 88 ].

Euthanasia is a term derived from Greek, and it means a death without any suffering. According to the Brazilian Arouca Law (Article 14, Chapter IV, Paragraphs 1 and 2), an animal should undergo euthanasia, in strict compliance with the requirements of each species, when the experiment ends or during any phase of the experiment, wherever this procedure is recommended and/or whenever serious suffering occurs. If the animal does not undergo euthanasia after the intervention it may leave the vivarium and be assigned to suitable people or to the animal protection bodies, duly legalized [ 1 ].

Euthanasia procedures must result in instant loss of consciousness which leads to respiratory or cardiac arrest as well as to complete brain function impairment. Another important aspect of this procedure is calm handling of the animal while taking it out of its enclosure, to reduce its distress, suffering, anxiety and fear. In every research project, the study design should include the details of the appropriate endpoints of these experimental animals, and also the methods that will be adopted. It is important to determine the appropriate method of euthanasia for the animal being used. Another important point is that, after completing the euthanasia procedure, the animal’s death should be absolutely confirmed before discarding their bodies [ 87 , 89 ].

Relevance of animal experimentations and possible alternatives

Relevance of animal experiments and their adverse effects on human health.

One important concern is whether human diseases, when inflicted on experimental animals, adequately mimic the progressions of the disease and the treatment responses observed in humans. Several research articles have made comparisons between human and animal data, and indicated that the results of animals’ research could not always be reliably replicated in clinical research among humans. The latest systematic reviews about the treatment of different clinical conditions including neurology, vascular diseases and others, have established that the results of animal studies cannot properly predict human outcomes [ 59 , 90 ].

At present, the reliability of animal experiments for extrapolation to human health is questionable. Harmful effects may occur in humans because of misleading results from research conducted on animals. For instance, during the late fifties, a sedative drug, thalidomide, was prescribed for pregnant women, but some of the women using that drug gave birth to babies lacking limbs or with foreshortened limbs, a condition called phocomelia. When thalidomide had been tested on almost all animal models such as rats, mice, rabbits, dogs, cats, hamsters, armadillos, ferrets, swine, guinea pig, etc., this teratogenic effect was observed only occasionally [ 91 ]. Similarly, in 2006, the compound TGN 1412 was designed as an immunomodulatory drug, but when it was injected into six human volunteer, serious adverse reactions were observed resulting from a deadly cytokine storm that in turn led to disastrous systemic organ failure. TGN 1412 had been tested successfully in rats, mice, rabbits, and non-human primates [ 92 ]. Moreover, Bailey (2008) reported 90 HIV vaccines that had successful trial results in animals but which failed in human beings [ 93 ]. Moreover, in Parkinson disease, many therapeutic options that have shown promising results in rats and non-human primate models have proved harmful in humans. Hence, to analyze the relevance of animal research to human health, the efficacy of animal experimentation should be examined systematically [ 94 , 95 ]. At the same time, the development of hyperoxaluria and renal failure (up to dialysis) after ileal-jejunal bypass was unexpected because this procedure was not preliminarily evaluated on an animal model [ 96 ].

Several factors play a role in the extrapolation of animal-derived data to humans, such as environmental conditions and physiological parameters related to stress, age of the experimental animals, etc. These factors could switch on or off genes in the animal models that are specific to species and/or strains. All these observations challenge the reliability and suitability of animal experimentation as well as its objectives with respect to human health [ 76 , 92 ].

ALTERNATIVE TO ANIMAL EXPERIMENTATION/DEVELOPMENT OF NEW PRODUCTS AND TECHNIQUES TO AVOID ANIMAL SACRIFICE IN RESEARCH

Certainly, in vivo animal experimentation has significantly contributed to the development of biological and biomedical research. However it has the limitations of strict ethical issues and high production cost. Some scientists consider animal testing an ineffective and immoral practice and therefore prefer alternative techniques to be used instead of animal experimentation. These alternative methods involve in vitro experiments and ex vivo models like cell and tissue cultures, use of plants and vegetables, non-invasive human clinical studies, use of corpses for studies, use of microorganisms or other simpler organism like shrimps and water flea larvae, physicochemical techniques, educational software, computer simulations, mathematical models and nanotechnology [ 97 ]. These methods and techniques are cost-effective and could efficiently replace animal models. They could therefore, contribute to animal welfare and to the development of new therapies that can identify the therapeutics and related complications at an early stage [ 1 ].

The National Research Council (UK) suggested a shift from the animal models toward computational models, as well as high-content and high-throughput in vitro methods. Their reports highlighted that these alternative methods could produce predictive data more affordably, accurately and quickly than the traditional in vivo or experimental animal methods [ 98 ].

Increasingly, scientists and the review boards have to assess whether addressing a research question using the applied techniques of advanced genetics, molecular, computational and cell biology, and biochemistry could be used to replace animal experiments [ 59 ]. It must be remembered that each alternative method must be first validated and then registered in dedicated databases.

An additional relevant concern is how precisely animal data can mirror relevant epigenetic changes and human genetic variability. Langley and his colleagues have highlighted some of the examples of existing and some emerging non-animal based research methods in the advanced fields of neurology, orthodontics, infectious diseases, immunology, endocrine, pulmonology, obstetrics, metabolism and cardiology [ 99 ].

IN SILICO SIMULATIONS AND INFORMATICS

Several computer models have been built to study cardiovascular risk and atherosclerotic plaque build-up, to model human metabolism, to evaluate drug toxicity and to address other questions that were previously approached by testing in animals [ 100 ].

Computer simulations can potentially decrease the number of experiments required for a research project, however simulations cannot completely replace laboratory experiments. Unfortunately, not all the principles regulating biological systems are known, and computer simulation provide only an estimation of possible effects due to the limitations of computer models in comparison with complex human tissues. However, simulation and bio-informatics are now considered essential in all fields of science for their efficiency in using the existing knowledge for further experimental designs [ 76 ].

At present, biological macromolecules are regularly simulated at various levels of detail, to predict their response and behavior under certain physical conditions, chemical exposures and stimulations. Computational and bioinformatic simulations have significantly reduced the number of animals sacrificed during drug discovery by short listing potential candidate molecules for a drug. Likewise, computer simulations have decreased the number of animal experiments required in other areas of biological science by efficiently using the existing knowledge. Moreover, the development of high definition 3D computer models for anatomy with enhanced level of detail, it may make it possible to reduce or eliminate the need for animal dissection during teaching [ 101 , 102 ].

3D CELL-CULTURE MODELS AND ORGANS-ON-CHIPS

In the current scenario of rapid advancement in the life sciences, certain tissue models can be built using 3D cell culture technology. Indeed, there are some organs on micro-scale chip models used for mimicking the human body environment. 3D models of multiple organ systems such as heart, liver, skin, muscle, testis, brain, gut, bone marrow, lungs and kidney, in addition to individual organs, have been created in microfluidic channels, re-creating the physiological chemical and physical microenvironments of the body [ 103 ]. These emerging techniques, such as the biomedical/biological microelectromechanical system (Bio-MEMS) or lab-on-a-chip (LOC) and micro total analysis systems (lTAS) will, in the future, be a useful substitute for animal experimentation in commercial laboratories in the biotechnology, environmental safety, chemistry and pharmaceutical industries. For 3D cell culture modeling, cells are grown in 3D spheroids or aggregates with the help of a scaffold or matrix, or sometimes using a scaffold-free method. The 3D cell culture modeling conditions can be altered to add proteins and other factors that are found in a tumor microenvironment, for example, or in particular tissues. These matrices contain extracellular matrix components such as proteins, glycoconjugates and glycosaminoglycans that allow for cell communication, cell to cell contact and the activation of signaling pathways in such a way that the morphological and functional differentiation of these cells can accurately mimic their environment in vivo . This methodology, in time, will bridge the gap between in vivo and in vitro drug screening, decreasing the utilization of animal models during research [ 104 ].

ALTERNATIVES TO MICROBIAL CULTURE MEDIA AND SERUM-FREE ANIMAL CELL CULTURES

There are moves to reduce the use of animal derived products in many areas of biotechnology. Microbial culture media peptones are mostly made by the proteolysis of farmed animal meat. However, nowadays, various suppliers provide peptones extracted from yeast and plants. Although the costs of these plant-extracted peptones are the same as those of animal peptones, plant peptones are more environmentally favorable since less plant material and water are required for them to grow, compared with the food grain and fodder needed for cattle that are slaughtered for animal peptone production [ 105 ].

Human cell culture is often carried out in a medium that contains fetal calf serum, the production of which involves animal (cow) sacrifice or suffering. In fact, living pregnant cows are used and their fetuses removed to harvest the serum from the fetal blood. Fetal calf serum is used because it is a natural medium rich in all the required nutrients and significantly increases the chances of successful cell growth in culture. Scientists are striving to identify the factors and nutrients required for the growth of various types of cells, with a view to eliminating the use of calf serum. At present, most cell lines could be cultured in a chemically-synthesized medium without using animal products. Furthermore, data from chemically-synthesized media experiments may have better reproducibility than those using animal serum media, since the composition of animal serum does change from batch to batch on the basis of animals’ gender, age, health and genetic background [ 76 ].

ALTERNATIVES TO ANIMAL-DERIVED ANTIBODIES

Animal friendly affinity reagents may act as an alternative to antibodies produced, thereby removing the need for animal immunization. Typically, these antibodies are obtained in vitro by yeast, phage or ribosome display. In a recent review, a comparative analysis between animal friendly affinity reagents and animal derived-antibodies showed that the affinity reagents have superior quality, are relatively less time consuming, have more reproducibility and are more reliable and are cost-effective [ 106 , 107 ].

Conclusions

Animal experimentation led to great advancement in biological and biomedical sciences and contributed to the discovery of many drugs and treatment options. However, such experimentation may cause harm, pain and distress to the animals involved. Therefore, to perform animal experimentations, certain ethical rules and laws must be strictly followed and there should be proper justification for using animals in research projects. Furthermore, during animal experimentation the 4 Rs principles of reduction, refinement, replacement and responsibility must be followed by the researchers. Moreover, before beginning a research project, experiments should be thoroughly planned and well-designed, and should avoid unnecessary use of animals. The reliability and reproducibility of animal experiments should also be considered. Whenever possible, alternative methods to animal experimentation should be adopted, such as in vitro experimentation, cadaveric studies, and computer simulations.

While much progress has been made on reducing animal experimentation there is a need for greater awareness of alternatives to animal experiments among scientists and easier access to advanced modeling technologies. Greater research is needed to define a roadmap that will lead to the elimination of all unnecessary animal experimentation and provide a framework for adoption of reliable alternative methodologies in biomedical research.

Acknowledgements

This research was funded by the Provincia Autonoma di Bolzano in the framework of LP 15/2020 (dgp 3174/2021).

Conflicts of interest statement

Authors declare no conflict of interest.

Author's contributions

MB: study conception, editing and critical revision of the manuscript; AKK, DP, GH, RB, Paul S, Peter S, RM, BF, NC, SM, LL, DD, GMT, MCE, MD, SM, Daniele M, GB, AD, KD, MCM, TB, MS, STC, Donald M, AM, AB, KLH, MK, LS, LL, GF: literature search, editing and critical revision of the manuscript. All authors have read and approved the final manuscript.

Contributor Information

INTERNATIONAL BIOETHICS STUDY GROUP : Derek Pheby , Gary Henehan , Richard Brown , Paul Sieving , Peter Sykora , Robert Marks , Benedetto Falsini , Natale Capodicasa , Stanislav Miertus , Lorenzo Lorusso , Gianluca Martino Tartaglia , Mahmut Cerkez Ergoren , Munis Dundar , Sandro Michelini , Daniele Malacarne , Tommaso Beccari , Michele Samaja , Matteo Bertelli , Donald Martin , Assunta Morresi , Ariola Bacu , Karen L. Herbst , Mykhaylo Kapustin , Liborio Stuppia , Ludovica Lumer , and Giampietro Farronato

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• The Debate on Animal Experimentation
• Medical Advancement: Research done on animals can save countless human lives. It has already led to the discovery of insulin and hepatitis C; vaccines against polio and hepatitis B; and procedures such as open heart surgeries, coronary bypass surgery, and heart transplantation. Many animals, especially primates, share about 90% of their genetic make-ups with humans, so experimenting on such animals can give scientists a good idea about possible reactions in the human body. Further, new medicines can help animals too, since breakthroughs in veterinary medicine have also occurred due to animal experimentation.
• Product Safety: Animal testing helps ensure the safety of drugs and other substances that humans may be exposed to on a daily basis, such as cosmetics. It helps minimize the chances of adverse human reactions, such as rash, itching, or even death, during human clinical trials. Animals used for such safety testing are usually not killed and remain relatively healthy. Furthermore, animals such as mice and rabbits usually reproduce very quickly.

Cons to Animal Testing

• Pain, Suffering, and Death: Most companies claim that no animals were hurt during animal experimentation, but there nonetheless exists a shadow of doubt. Testing potentially includes the jabbing of needles, storage into cramped spaces, and lack of quality/quantity in nutrition. Some animals may die over the course of the experiment or be killed after their use, and others may lose their limbs, eyesight, hearing, muscle coordination, and so on. In some cases, many of the substances tested may never even see approval of public consumption and use; thus, these animals may have undergone such treatment in vain, seeing that no direct benefit to humans occurred.
• Ethics: Since animals cannot volunteer themselves for testing and cannot voice their opinions, some people believe that it is only ethical to test on subjects who willingly give their consent for self testing.
• Price: Animal testing is expensive, as one must pay for food, housing, and maintenance, as well as the initial cost of breeding/buying the animal. This is a cost that may reoccur over the course of several months, even years.
• Accuracy: Although testing on animals are the best alternative to actual humans, there is still an important margin of error, and some people still believe animal testing to be unreliable. A reason for this, other than genetic makeup, is that the animals are kept in an unnatural environment (the laboratory) that places them under stress, which may alter their response.

All in all, both sides of animal testing seems to tilt the scales equally. Animal testing may save millions of human lives, but at the expense of the lives of animals. In the end, taking the pros and cons into consideration, animal testing highlights the fine line between ethics and practical need, and the ultimate decision is subjective to the values of each individual.

Article by Sherry Jiaa

Feature Image Source: Science 

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Facts and Statistics About Animal Testing

Each year, more than 110 million animals—including mice, rats, frogs, dogs, cats, rabbits, hamsters, guinea pigs, monkeys, fish, and birds—are killed in U.S. laboratories for biology lessons, medical training, curiosity-driven experimentation, and chemical, drug, food, and cosmetics testing. Before their deaths, some are forced to inhale toxic fumes, others are immobilized in restraint devices for hours, some have holes drilled into their skulls, and others have their skin burned off or their spinal cords crushed. In addition to the torment of the actual experiments, animals in laboratories are deprived of everything that is natural and important to them—they are confined to barren cages, socially isolated, and psychologically traumatized. The thinking, feeling animals who are used in experiments are treated like nothing more than disposable laboratory equipment.

Animal Experiments Are Wasteful and Unreliable

A Pew Research Center poll found that 52 percent of U.S. adults oppose the use of animals in scientific research, and other surveys suggest that the shrinking group that does accept animal experimentation does so only because it believes it to be necessary for medical progress. 5,6 The majority of animal experiments do not contribute to improving human health, and the value of the role that animal experimentation plays in most medical advances is questionable.

In an article published in The Journal of the American Medical Association , researchers found that medical treatments developed in animals rarely translated to humans and warned that “patients and physicians should remain cautious about extrapolating the finding of prominent animal research to the care of human disease … poor replication of even high-quality animal studies should be expected by those who conduct clinical research.” 7

Diseases that are artificially induced in animals in a laboratory, whether they be mice or monkeys, are never identical to those that occur naturally in human beings. And because animal species differ from one another biologically in many significant ways, it becomes even more unlikely that animal experiments will yield results that will be correctly interpreted and applied to the human condition in a meaningful way.

For example, according to former National Cancer Institute Director Dr. Richard Klausner, “We have cured mice of cancer for decades, and it simply didn’t work in humans.” 8 This conclusion was echoed by former National Institutes of Health (NIH) Director Dr. Elias Zerhouni, who acknowledged that experimenting on animals has been a boondoggle. “We have moved away from studying human disease in humans,” he said. “We all drank the Kool-Aid on that one, me included. … The problem is that it hasn’t worked, and it’s time we stopped dancing around the problem. … We need to refocus and adapt new methodologies for use in humans to understand disease biology in humans.” 9

The data is sobering: Although at least 85 HIV/AIDS vaccines have been successful in nonhuman primate studies, as of 2015, every one has failed to protect humans. 10 In one case, an AIDS vaccine that was shown to be effective in monkeys failed in human clinical trials because it did not prevent people from developing AIDS, and some believe that it made them more susceptible to the disease. According to a report in the British newspaper The Independent , one conclusion from the failed study was that “testing HIV vaccines on monkeys before they are used on humans, does not in fact work.” 11

These are not anomalies. The National Institutes of Health has stated, “Therapeutic development is a costly, complex and time-consuming process. The average length of time from target discovery to approval of a new drug is about 14 years. The failure rate during this process exceeds 95 percent, and the cost per successful drug can be $1 billion or more.” 12

Research published in the journal Annals of Internal Medicine revealed that universities commonly exaggerate findings from animal experiments conducted in their laboratories and “often promote research that has uncertain relevance to human health and do not provide key facts or acknowledge important limitations.” 13 One study of media coverage of scientific meetings concluded that news stories often omit crucial information and that “the public may be misled about the validity and relevance of the science presented.” 14 Because experimenters rarely publish results of failed animal studies, other scientists and the public do not have ready access to information on the ineffectiveness of animal experimentation.

Funding and Accountability

Through their taxes, charitable donations, and purchases of lottery tickets and consumer products, members of the public are ultimately the ones who—knowingly or unknowingly—fund animal experimentation. One of the largest sources of funding comes from publicly funded government granting agencies such as NIH. Approximately 47 percent of NIH-funded research involves experimentation on animals, and in 2020, NIH budgeted nearly $42 billion for research and development. 15,16 In addition, many charities––including the March of Dimes, the American Cancer Society, and countless others—use donations to fund experiments on animals. One-third of the projects funded by the National Multiple Sclerosis Society involve animal experimentation. 17

Despite the vast amount of public funds being used to underwrite animal experimentation, it is nearly impossible for the public to obtain current and complete information regarding the animal experiments that are being carried out in their communities or funded with their tax dollars. State open-records laws and the U.S. Freedom of Information Act can be used to obtain documents and information from state institutions, government agencies, and other federally funded facilities, but private companies, contract labs, and animal breeders are exempt. In many cases, institutions that are subject to open-records laws fight vigorously to withhold information about animal experimentation from the public. 18

Oversight and Regulation

Despite the countless animals killed each year in laboratories worldwide, most countries have grossly inadequate regulatory measures in place to protect animals from suffering and distress or to prevent them from being used when a non-animal approach is readily available. In the U.S., the species most commonly used in experiments (mice, rats, birds, fish, reptiles, and amphibians) comprise 99% of all animals in laboratories but are specifically exempted from even the minimal protections of the federal Animal Welfare Act (AWA). 19,20 Many laboratories that use only these species are not required by law to provide animals with pain relief or veterinary care, to search for and consider alternatives to animal use, to have an institutional committee review proposed experiments, or to be inspected by the U.S. Department of Agriculture (USDA) or any other entity. Some estimates indicate that as many as 800 U.S. laboratories are not subject to federal laws and inspections because they experiment exclusively on mice, rats, and other animals whose use is largely unregulated. 21

As for the more than 11,000 facilities that the USDA does regulate (of which more than 1,200 are designated for “research”), only 120 USDA inspectors are employed to oversee their operations. 22 Reports have repeatedly concluded that even the minimal standards set forth by the AWA are not being met by these facilities, and institutionally based oversight bodies, called Institutional Animal Care and Use Committees (IACUCs), have failed to carry out their mandate. A 1995 report by the USDA’s Office of the Inspector General (OIG) “found that the activities of the IACUCs did not always meet the standards of the AWA. Some IACUCs did not ensure that unnecessary or repetitive experiments would not be performed on laboratory animals.” 23 In 2000, a USDA survey of the agency’s laboratory inspectors revealed serious problems in numerous areas, including “the search for alternatives [and] review of painful procedures.” 24  A September 2005 audit report issued by the OIG found ongoing “problems with the search for alternative research, veterinary care, review of painful procedures, and the researchers’ use of animals.” 25 In December 2014, an OIG report documented continuing problems with laboratories failing to comply with the minimal AWA standards and the USDA’s weak enforcement actions failing to deter future violations. The audit highlighted that from 2009 to 2011, USDA inspectors cited 531 experimentation facilities for 1,379 violations stemming from the IACUCs’ failure to adequately review and monitor the use of animals. The audit also determined that in 2012, the USDA reduced its penalties to AWA violators by an average of 86 percent, even in cases involving animal deaths and egregious violations. 26

Research co-authored by PETA documented that, on average, animal experimenters and laboratory veterinarians comprise a combined 82 percent of the membership of IACUCs at leading U.S. institutions. A whopping 98.6 percent of the leadership of these IACUCs was also made up of animal experimenters. The authors observed that the dominant role played by animal experimenters on these committees “may dilute input from the few IACUC members representing animal welfare and the general public, contribute to previously-documented committee bias in favor of approving animal experiments and reduce the overall objectivity and effectiveness of the oversight system.” 27 Even when facilities are fully compliant with the law, animals who are covered can be burned, shocked, poisoned, isolated, starved, forcibly restrained, addicted to drugs, and brain-damaged. No procedures or experiments, regardless of how trivial or painful they may be, are prohibited by federal law. When valid non-animal research methods are available, no federal law requires experimenters to use such methods instead of animals.

Alternatives to Animal Testing

A high-profile study published in the prestigious BMJ (formerly British Medical Journal ) documenting the ineffectiveness and waste of experimentation on animals concluded that “if research conducted on animals continues to be unable to reasonably predict what can be expected in humans, the public’s continuing endorsement and funding of preclinical animal research seems misplaced.” 28

Research with human volunteers, sophisticated computational methods, and in vitro studies based on human cells and tissues are critical to the advancement of medicine. Cutting-edge non-animal research methods are available and have been shown time and again to be more accurate than crude animal experiments. 29 However, this modern research requires a different outlook, one that is creative and compassionate and embraces the underlying philosophy of ethical science. Human health and well-being can also be promoted by adopting nonviolent methods of scientific investigation and concentrating on the prevention of disease before it occurs, through lifestyle modification and the prevention of further environmental pollution and degradation. The public is becoming more aware and more vocal about the cruelty and inadequacy of the current research system and is demanding that tax dollars and charitable donations not be used to fund experiments on animals.

History of Animal Testing

PETA created “ Without Consent ”—an interactive timeline featuring almost 200 stories of animal experiments from the past century—to open people’s eyes to the long history of suffering that’s been inflicted on nonconsenting animals in laboratories and to challenge people to rethink this exploitation. Visit “ Without Consent ” to learn more about harrowing animal experiments throughout history and how you can help create a better future for living, feeling beings.

You Can Help Stop Animal Testing

Virtually all federally funded research is paid for with your tax dollars. Your lawmakers needs to know that you don’t want your money used to pay for animal experiments.

Urge your members of Congress to endorse PETA’s Research Modernization Deal , which provides a roadmap for modernizing U.S. investment in research by ending funding for useless experiments on animals and investing in effective research that’s relevant to humans.

Animal Testing Facts and Figures

U.S. (2022) 1,2

• In 2022, more than 1.27 million animals were held captive in laboratories or used in experiments, excluding rats, mice, birds, reptiles, amphibians, and agricultural animals used in agricultural experiments. The number of mice and rats is estimated to have been 111 million.

Canada (2022) 3

• Institutions certified by the Canadian Council on Animal Care (CCAC) reported that 3.52 million animals were used in experiments in 2022.*
• Of these, 105,253 animals were subjected to “severe pain near, at, or above the pain tolerance threshold of unanesthetized conscious animals.”

*The CCAC is a “national peer-review organization” funded by the Canadian government but with no regulatory capacity. Only institutions that receive public funds are required to be certified by the CCAC, and the figures reported by the organization reflect only this subset of facilities. Most private research facilities are not certified by the CCAC, and their use of animals is therefore not included in the organization’s figures.

U.K. (2022) 4

• In 2022, 76 million procedures were conducted on animals.
• Of those, 110,400 were assessed to be “severe,” including “long-term disease processes where assistance with normal activities such as feeding and drinking are required or where significant deficits in behaviours/activities persist.”

1 Data from all 2022 annual reports was derived from the U.S. Department of Agriculture’s public search tool . 2 Larry Carbone, “ Estimating Mouse and Rat Use in American Laboratories by Extrapolation From Animal Welfare Act–Regulated Species ,” Scientific Reports 11, 493 (2021). 3 CCAC, “ CCAC Animal Data Report 2022 ,” 2023. 4 U.K. Government, “ Annual Statistics of Scientific Procedures on Living Animals, Great Britain 2022 ,” Home Office, July 13, 2023. 5 Cary Funk and Meg Hefferon, “ Most Americans Accept Genetic Engineering of Animals That Benefits Human Health, but Many Oppose Other Uses ,” Pew Research Center, 16 Aug. 2018 6 Peter Aldhous and Andy Coghlan, “ Let the People Speak ,” New Scientist 22 May 1999. 7 Daniel G. Hackam, M.D., and Donald A. Redelmeier, M.D., “ Translation of Research Evidence From Animals to Human ,” The Journal of the American Medical Association 296 (2006): 1731-2. 8 Marlene Simmons et al., “ Cancer-Cure Story Raises New Questions ,” Los Angeles Times 6 May 1998. 9 Rich McManus, “Ex-Director Zerhouni Surveys Value of NIH Research,” NIH Record 21 June 2013. 10 Jarrod Bailey, “ An Assessment of the Role of Chimpanzees in AIDS Vaccine Research ,” Alternatives to Laboratory Animals 36 (2008): 381-428. 11 Steve Connor and Chris Green, “ Is It Time to Give Up the Search for an AIDS Vaccine? ” The Independent 24 Apr. 2008. 12 National Institutes of Health, “ About New Therapeutic Uses ,” National Center for Advancing Translational Sciences 9 Oct. 2019. 13 Steve Woloshin, M.D., M.S., et al ., “ Press Releases by Academic Medical Centers: Not So Academic? ” Annals of Internal Medicine 150 (2009): 613-8. 14 Steven Woloshin and Lisa Schwartz, “ Media Reporting on Research Presented at Scientific Meetings: More Caution Needed ,” The Medical Journal of Australia 184 (2006): 576-80. 15 Diana E. Pankevich et a l., “ International Animal Research Regulations: Impact on Neuroscience Research ,” The National Academies (2012). 16 National Institutes of Health, “ Budget ,” (last accessed on 3 May 2021). 17 Pankevich et a l. 18 Deborah Ziff, “ On Campus: PETA Sues UW Over Access to Research Records ,” Wisconsin State Journal 5 Apr. 2010. 19 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, “Animal Welfare, Definition of Animal,” Federal Register, 69 (2004): 31513-4. 20 Justin Goodman et al. , “ Trends in Animal Use at US Research Facilities ,” Journal of Medical Ethics 0(2015): 1-3. 21 The Associated Press, “Animal Welfare Act May Not Protect All Critters,” 7 May 2002. 22 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, “Animal Care: Search.” 23 U.S. Department of Agriculture, Office of Inspector General, “ APHIS Animal Care Program, Inspection and Enforcement Activities ,” audit report, 30 Sept. 2005. 24 U.S. Department of Agriculture, Animal and Plant Health Inspection Service, “ USDA Employee Survey on the Effectiveness of IACUC Regulations ,” Apr. 2000. 25 U.S. Department of Agriculture, Office of Inspector General, “APHIS Animal Care Program, Inspection and Enforcement Activities,” audit report, 30 Sept. 2005. 26 U.S. Department of Agriculture, Office of Inspector General, “ Animal and Plant Health Inspection Service Oversight of Research Facilities ,” audit report, Dec. 2014. 27 Lawrence A. Hansen et a l., “ Analysis of Animal Research Ethics Committee Membership at American Institutions ,” Animals 2 (2012): 68-75. 28 Pandora Pound and Michael Bracken, “ Is Animal Research Sufficiently Evidence Based To Be A Cornerstone of Biomedical Research? ,” BMJ (2014): 348. 29 Junhee Seok et al ., “ Genomic Responses in Mouse Models Poorly Mimic Human Inflammatory Diseases ,” Proceedings of the National Academy of Sciences 110 (2013): 3507-12.

The U.S. Fish & Wildlife Service may toss out a two-year-long de facto ban to fuel worthless experiments in the U.S. Take action now!

Removing the protection of rhesus macaque monkeys will expose them to capture, abuse, and exploitation.

A just-released report reveals a laundry list of violations in a tax-funded laboratory at Emory University, where, among other horrors, experimenters caused a baby monkey to suffer.

Please urge SkyTaxi to stop flying these animals to their deaths.

Please urge the FDA not to ask for animal tests and to instead collaborate on the development of a non-animal testing approach that protects human health without harming animals.

PETA shut down one miserable lab in Colombia and got the authorities to rescue all the animals. Now, we’ve uncovered another. We need your help to stop it from killing any more monkeys.

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• Are animal experiments necessary?

Are animal experiments necessary and justified?

Animal experiments are one of the traditional approaches to studying how human and animal bodies work (in health and illness) and for testing medicines and chemicals. But are they necessary and justified?

Scientists who use animals argue that there is currently no other way to achieve their scientific objectives and that any pain or distress caused to the animals is outweighed by the potential benefits of their research.

There is a range of views on how much suffering should be allowed, for what purpose (e.g. aiming to treat cancer, drug addiction, or male pattern baldness, to assess the safety of a new industrial chemical, or to find out how birds navigate) and to what species of animal.

UK law on animal experiments

'Necessity' and 'justification' of the use of animals are both matters of opinion and open to debate. The UK law that controls animal experiments is supposed to reflect this. It requires that:

• The likely harms to the animals are weighed against the potential benefits of the project.
• There are no alternatives available.
• The number of animals and degree of suffering is minimised.

This provides a framework for making decisions about animal experiments, but the system should be implemented more effectively. For example, it's often suggested that most animal experiments are 'life-saving' medical research and are all done to the 'highest possible standards.' But sweeping statements like these don't stand up to scrutiny, for two main reasons:

• There's serious debate within the scientific community about the value of information obtained from many animal tests, and about the relevance of various animal 'models' - and this raises doubts about the scientific validity of applying the results from research on animals to humans.
• There are concerns about the poor quality of much animal research that's conducted.

Scientific validity of animal experiments

The issues relating to scientific validity and quality are deeply worrying. Research that's of little value, poorly designed or conducted and badly reported is a waste of animals' lives, causing suffering that should have been entirely avoidable. Animal experiments like these are certainly neither necessary nor justified.

Efforts are at last beginning to be made to recognise and address these problems, and the concerns don't apply to all scientists and research areas. However, poor-quality animal research continues to be funded, licensed, carried out and published. This should stop.

The RSPCA view on animal experiments

Our views on the use of animals in experiments are as follows:

• The scientific community, including researchers, funding bodies, journal editors and the Home Office, should do much more to critically review the scientific validity of animal experiments.
• The 'need' to use animals, and the justification for the suffering caused, should both be challenged much more strongly. Animals' lives and welfare should be given higher priority.
• Badly designed and poorly carried out experiments are invalid science and waste animals' lives. They should not be licensed by the Home Office, given grants by funding bodies or published in scientific journals.
• Even scientifically valid research may not add significantly to knowledge in its field, or it may only be of interest to a few people. This does not justify harming animals.
• Decisions about animal use are largely made by scientists, for scientists - a wider range of perspectives should be involved.

We want to see an end to animal suffering in the name of science. A more humane approach is needed.

Relevant Documents

Report: The ethics of research involving animals

Find out more

Ethical review

Ethical review is an essential part of any system regulating animal use in research and testing.

Harm-benefit analysis

Considering the potential benefits of a research project against the likely harms to animals.

Replacing animals

All experiments causing animal suffering should be replaced with humane alternatives.

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Common-garden experiment reveals outbreeding depression and region-of-origin effects on reproductive success in a frequently translocated tortoise

Human-mediated animal movement can expose wildlife populations to novel environments. Phenotypic plasticity can buffer against the challenges presented by novel environments, while adaptation to local ecosystems may limit resilience in novel ecosystems. Outbreeding depression during the mixing of disparate gene pools can also reduce reproductive success after long-distance movement. Here, we use a ‘common-garden’ population of gopher tortoises (Gopherus polyphemus), translocated from numerous sites across the state of Florida, USA, to a mitigation site in the north-west (panhandle) region to assess whether geographic origin, outbreeding effects, and behavioral plasticity influence reproductive success in this threatened keystone species. We found that females from north-east Florida produced clutches with lower hatching success than females from other regions. We detected regional differentiation in nest site selection behavior in the common environment of the translocation site, though these differences did not mediate the regional effect on hatching success. We also found evidence for outbreeding depression: hatching success declined with increasing parental geographic and genetic distances, dropping from 93% to 67% across the range of observed parental genetic distances. Together, these results suggest that newly admixed populations may suffer reproductive costs due to historical population differentiation, and that undetected outbreeding depression could significantly hamper conservation efforts for this species and others undergoing a variety of human-mediated movements.

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Elizabeth a. hunter, phd, research ecologist.