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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.

Investigations

Breaking investigation once again reveals shocking cruelty and abuse faced by animals in European laboratory

Toxicity testing on animals at Vivotecnia, Spain

subtitle: Breaking investigation once again reveals shocking cruelty and abuse faced by animals in European laboratory

Investigation

Undercover video footage reveals terrible plight of animals at Laboratory of Pharmacology and Toxicology

Toxicity testing at LPT, Germany

subtitle: Undercover video footage reveals terrible plight of animals at Laboratory of Pharmacology and Toxicology

Exposed: Appalling suffering at a UK animal testing laboratory

Veterinary schools using dogs, Japan

subtitle: Exposed: Appalling suffering at a UK animal testing laboratory

Street dogs are being used in student veterinary classes

Investigation at Khon Kaen University, Thailand

subtitle: Street dogs are being used in student veterinary classes

Our investigation uncovers the horror of life for monkeys in a top European animal experiments laboratory

Monkey experiments at Max Planck Institute, Germany

subtitle: Our investigation uncovers the horror of life for monkeys in a top European animal experiments laboratory

Investigation at University of Cambridge, United Kingdom

A Cruelty Free International investigation in 2013 uncovered the shocking use of very young puppies and kittens in animal experiments in a UK laboratory.

Dog and cat experiments at MSD Animal Health, United Kingdom

subtitle: A Cruelty Free International investigation in 2013 uncovered the shocking use of very young puppies and kittens in animal experiments in a UK laboratory.

Our investigation exposes the cruel use of wild baboons in for animal experiments

Experiments on wild baboons in Kenya

subtitle: Our investigation exposes the cruel use of wild baboons in for animal experiments

We uncovered the terrible plight of animals used in research at this ‘world-leading’ UK university.

Animal experiments at Imperial College London, United Kingdom

subtitle: We uncovered the terrible plight of animals used in research at this ‘world-leading’ UK university.

Animal experiments at Wickham Laboratories, United Kingdom

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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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Animal experimentation

Nonhuman animals are used in laboratories for a number of purposes. Examples of animal experimentation include product testing, use of animals as research models and as educational tools. Within each of these categories, there are also many different purposes for which they are used. For instance, some are used as tools for military or biomedical research; some to test cosmetics and household cleaning products, and some are used in class dissection to teach teenagers the anatomy of frogs or to have a subject for a Ph.D. dissertation.

The number of animals used in animal experimentation is certainly smaller than that of those used in others such as animal farming or the fishing industry. 1  Yet it has been estimated to be well above 100 million animals who are used every year. 2

The ways in which these animals can be harmed in experimental procedures, also known as vivisection, 3 vary. In almost all cases they are very significant and the majority of them end with the death of the animals.

There’s an important difference today between the consideration that is afforded to the potential and actual subjects used in experiments, depending on whether they are human or nonhuman animals. Few people today would condone experimenting on human beings in harmful ways, and in fact, indicative of this, such research is strongly restricted by law, when it isn’t just prohibited outright. When experimentation on humans is permitted it is always in a context of the individuals involved consenting to it, for whatever personal benefit that serves as an incentive for them. For nonhuman animals, this is not the case.

This is not because of any belief that experimentation on humans could not bring about important knowledge (in fact, it seems obvious that this practice would uncover far more useful and relevant knowledge than any experimentation on nonhuman animals ever can). Rather, the reason for this double standard is that nonhuman animals are not morally taken into account because the strong arguments against speciesism are not considered.

In the following sections the most important areas in which nonhuman animals are used in laboratories or classrooms, as well as the research methods that don’t use them, are addressed.

Animals used for experimentation

Environmental research.

Animals are made to suffer and are killed to test the impact that chemicals can have in the environment. Some of the most important environmentalist organizations have been lobbying for this practice and have often been successful despite the opposition of animal defenders.

Cosmetic and household products testing

While animal testing of new cosmetics and household products is now illegal in places such as the European Union and India, it’s still being carried out in the U.S. and other places, where many animals are blinded, caused extreme pain and killed.

Military experimentation

The use of animals to test new weaponry, bullets and warfare chemicals, as well as the effects of burns and poison for military purposes, remains mainly hidden today, but many animals die in terrible ways because of it.

Biomedical experimentation

Animals of a variety of species are harmed for numerous purposes in biomedical research because the non-animal methodologies aren’t implemented. Those animals are harmed in many ways that most people ignore.

Experimentation with new materials

When new materials are developed, they are often tested by using methods such as cell or tissue cultures, or computational models. However, materials are also commonly tested on animals who are killed afterwards.

Animals used in education

Animals used in primary and secondary education.

Dissecting animals and using them in other ways has been common practice in the U.S. and some other countries in primary and especially secondary education for many years. This means killing a huge number of animals and educating new generations in the idea that it’s acceptable to harm animals for our benefit.

Animals used in higher education

In the science departments of many different universities, research, teaching and training are successfully carried out without using animals as laboratory tools. However, animals are still subjected to all kind of procedures in many other places.

Towards a future without animals harmed in laboratories

Research methods that do not involve the use of nonhuman animals.

Defenders of animal experimentation often claim that there is no choice but to harm animals lest scientific progress be stopped, but this is not so. There are many non-harmful methods available today.

Companies that test on animals

Despite the fact that many other companies do not experiment on sentient animals, there are still companies that choose to continue carrying out animal tests out of a lack of will to implement new methods.

Companies that do not test on animals

Fortunately, although many companies today choose not to harm animals in product development, quality and safety isn’t affected in the least.

1 Every year tens of billions are killed in slaughterhouses and trillions are fished and killed in fish factories. For estimations regarding this see: Food and Agriculture Organization of the United Nations (2021) “ Livestock primary ”, FAO STAT , February 19 [accessed on 24 March 2013]. See also Mood, A. &  Brooke, P. (2010) “ Estimating the number of fish caught in global fishing each year ”, Fishcount.org.uk , July [accessed on 18 October 2020]; (2012) “ Estimating the number of farmed fish killed in global aquaculture each year ”, Fishcount.org.uk , July [accessed on 18 January 2021].

2  See Taylor, K.; Gordon, N.; Langley, G. & Higgins, W. (2008) “Estimates for worldwide laboratory animal use in 2005”,  Alternatives to Laboratory Animals , 36, pp. 327-342.

3 Although the term “vivisection” literally means “cutting a living animal,” this word has broadened its meaning in common language to denote any kind of laboratory invasive use of an animal. Defenders of animal experimentation prefer not to use it due to its negative connotations. Opponents of it claim that there shouldn’t be a problem with using this term given the meaning it already has in common language. They argue that its rejection is due to an intention to use language that is not explicit about how animals are used in this field.

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ANIMAL ETHICS IN OTHER LANGUAGES

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

What is ethical animal research? A scientist and veterinarian explain

Postdoctoral Research Fellow in Neuroscience, National Institutes of Health

Clinical Veterinarian, Emory National Primate Research Center, Emory University

Disclosure statement

Lana Ruvolo Grasser, Ph.D. is the 2022-2023 American College of Neuropsychopharmacology, Americans for Medical Progress Biomedical Research Awareness Day Fellow. She has previously received funding from the National Institute of Mental Health, Blue Cross Blue Shield Foundation of Michigan, and Wayne State University; none of which has supported the work described herein. She is a member of the Anxiety and Depression Association of America, International Society for Traumatic Stress Studies, International Society for Developmental Psychobiology, and Michigan Society for Neuroscience. Dr. Grasser contributed to this article in her personal capacity. The views expressed are her own and do not necessarily represent the views of the National Institutes of Health or the United States Government.

Rachelle Stammen works as a Clinical Veterinarian at the Emory National Primate Research Center. She is a member of the American Veterinary Medical Association, American Association of Laboratory Animal Science, Association of Primate Veterinarians, and a Diplomate of the American College of Laboratory Animal Medicine. This work is not affiliated with or reflect the opinions of Emory University or Emory National Primate Research Center.

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A proposed measure in Switzerland would have made that country the first to ban medical and scientific experimentation on animals. It failed to pass in February 2022, with only 21% of voters in favor. Yet globally, including in the United States , there is concern about whether animal research is ethical.

We are scientists who support ethical animal research that reduces suffering of humans and animals alike by helping researchers discover the causes of disease and how to treat it . One of us is a neuroscientist who studies behavioral treatments and medications for people with post-traumatic stress disorder – treatments made possible by research with dogs and rodents . The other is a veterinarian who cares for laboratory animals in research studies and trains researchers on how to interact with their subjects.

We both place high importance on ensuring that animal research is conducted ethically and humanely. But what counts as “ethical” animal research in the first place?

The 4 R’s of animal research

There is no single standard definition of ethical animal research. However, it broadly means the humane care of research animals – from their acquisition and housing to the study experience itself.

Federal research agencies follow guiding principles in evaluating the use and care of animals in research. One is that the research must increase knowledge and, either directly or indirectly, have the potential to benefit the health and welfare of humans and other animals. Another is that only the minimum number of animals required to obtain valid results should be included. Researchers must use procedures that minimize pain and distress and maximize the animals’ welfare. They are also asked to consider whether they could use nonanimal alternatives instead, such as mathematical models or computer simulations.

These principles are summarized by the “ 3 R’s” of animal research : reduction, refinement and replacement. The 3 R’s encourage scientists to develop new techniques that allow them to replace animals with appropriate alternatives.

Since these guidelines were first disseminated in the early 1960s , new tools have helped to significantly decrease animal research. In fact, since 1985, the number of animals in research has been reduced by half .

A fourth “R” was formalized in the late 1990s: rehabilitation , referring to care for animals after their role in research is complete.

These guidelines are designed to ensure that researchers and regulators consider the costs and benefits of using animals in research, focused on the good it could provide for many more animals and humans. These guidelines also ensure protection of a group – animals – that cannot consent to its own participation in research. There are a number of human groups that cannot consent to research, either, such as infants and young children, but for whom regulated research is still permitted, so that they can gain the potential benefits from discoveries .

Enforcing ethics

Specific guidelines for ethical animal research are typically established by national governments . Independent organizations also provide research standards.

In the U.S., the Animal Welfare Act protects all warmblooded animals except rats, mice and birds bred for research. Rats, mice and birds are protected – along with fish, reptiles and all other vertebrates – by the Public Health Service Policy .

Each institution that conducts animal research has an entity called the Institutional Animal Care and Use Committee , or IACUC. The IACUC is composed of veterinarians, scientists, nonscientists and members of the public. Before researchers are allowed to start their studies, the IACUC reviews their research protocols to ensure they follow national standards. The IACUC also oversees studies after approval to continually enforce ethical research practices and animal care. It, along with the U.S. Department of Agriculture , accreditation agencies and funding entities, may conduct unannounced inspections.

Laboratories that violate standards may be fined, forced to stop their studies, excluded from research funding, ordered to cease and desist, and have their licenses suspended or revoked. Allegations of misconduct are also investigated by the National Institutes of Health’s Office of Laboratory Animal Welfare .

Above and beyond the basic national standards for humane treatment, research institutions across 47 countries, including the U.S., may seek voluntary accreditation by a nonprofit called the Association for Assessment and Accreditation of Laboratory Animal Care , or AAALAC International. AAALAC accreditation recognizes the maintenance of high standards of animal care and use. It can also help recruit scientists to accredited institutes, promote scientific validity and demonstrate accountability.

Principles in practice

So what impact do these guidelines actually have on research and animals?

First, they have made sure that scientists create protocols that describe the purpose of their research and why animals are necessary to answer a meaningful question that could benefit health or medical care. While computer models and cell cultures can play an important role in some research, others studies, like those on Alzheimer’s disease , need animal models to better capture the complexities of living organisms. The protocol must outline how animals will be housed and cared for, and who will care for and work with the animals, to ensure that they are trained to treat animals humanely.

During continual study oversight, inspectors look for whether animals are provided with housing specifically designed for their species’ behavioral and social needs. For example, mice are given nesting materials to create a comfortable environment for living and raising pups . When animals don’t have environmental stimulation, it can alter their brain function – harming not only the animal, but also the science.

Monitoring agencies also consider animals’ distress. If something is known to be painful in humans, it is assumed to be painful in animals as well. Sedation, painkillers or anesthesia must be provided when animals experience more than momentary or slight pain.

For some research that requires assessing organs and tissues, such as the study of heart disease, animals must be euthanized. Veterinary professionals perform or oversee the euthanasia process. Methods must be in compliance with guidelines from the American Veterinary Medical Association , which requires rapid and painless techniques in distress-free conditions.

Fortunately, following their time in research, some animals can be adopted into loving homes , and others may be retired to havens and sanctuaries equipped with veterinary care, nutrition and enrichment.

Continuing the conversation

Animal research benefits both humans and animals. Numerous medical advances exist because they were initially studied in animals – from treatments for cancer and neurodegenerative disease to new techniques for surgery, organ transplants and noninvasive imaging and diagnostics .

These advances also benefit zoo animals, wildlife and endangered species. Animal research has allowed for the eradication of certain diseases in cattle , for example, leading not only to reduced farm cattle deaths and human famine, but also to improved health for wild cattle. Health care advances for pets – including cancer treatments , effective vaccines, nutritional prescription diets and flea and tick treatments – are also available thanks to animal research.

People who work with animals in research have attempted to increase public awareness of research standards and the positive effects animal research has had on daily life. However, some have faced harassment and violence from anti-animal research activists . Some of our own colleagues have received death threats.

Those who work in animal research share a deep appreciation for the creatures who make this work possible. For future strides in biomedical care to be possible, we believe that research using animals must be protected, and that animal health and safety must always remain the top priority.

Editor’s note: One photo depicting a species that is highly restricted for use in biomedical research has been removed from the article.

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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.

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.

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All Your Questions About Experiments on Animals Answered

What is animal testing? Every year in the U.S., tens of millions animals suffer and die in chemical, drug, food, and product tests. Animals are used in medical training exercises and in huge numbers in government- and taxpayer-funded curiosity-driven experiments at universities. They also suffer and die for classroom biology experiments and dissection, even though modern, non-animal methods have repeatedly been shown to have more educational value and save schools money.

Studies published in prestigious medical journals have repeatedly shown that animal experimentation wastes precious resources and lives.  The most recent independent study shows that 90% of basic research , most of which involves animals, fails to lead to treatments for humans.

Check out these facts about animal testing to learn more:

What is animal testing.

Animal testing refers to the practice of performing unnatural and often painful experiments on animals held captive in stressful laboratory settings, often in the misguided belief that the results of the tests will be applicable to humans. At the conclusion of most experiments, the subjects—millions of them per year—are killed.

Which Animals Are Used in Tests?

Right now, millions of mice , rats , rabbits , monkeys , cats , dogs , fish , and other animals used in tests are locked inside cages in laboratories across the country. They languish in pain, suffer from extreme frustration, ache with loneliness, and long to be free.

Exact numbers aren’t available, because mice, rats, birds, and cold-blooded animals—who make up more than 99% of animals used in experiments—are not protected under the federal Animal Welfare Act and their numbers don’t even have to be reported. These sentient beings aren’t even defined as “animals” under this act, which is the only federal law offering any sort of protection for animals.

Is Animal Testing Cruel?

Experimenting on animals is not only cruel but also completely unnecessary and unethical. The unnatural and stressful conditions of captivity make it even more unlikely that the results of animal tests can be applied to humans.

Published studies show that 90% of our fellow primates who are used in laboratories exhibit abnormal behavior patterns caused by the psychological stress, social isolation, and confinement to barren enclosures that they’re forced to endure. Many go insane, rocking back and forth, pacing endlessly inside cages, and doing repetitive motions such as back-flipping. They even engage in acts of self-mutilation, including tearing out their own hair and biting their own flesh.

Experiments on Animals at Colleges and Universities

The federal government and many health charities waste billions of dollars—including money from U.S. taxpayers—on animal experiments at universities and private laboratories, instead of supporting promising non-animal studies that could actually benefit humans.

Right now, animals in university laboratories are being mutilated, poisoned, deprived of food and water, immobilized in restraint devices, infected with painful and deadly diseases, burned, electrocuted, irradiated, addicted to drugs, and psychologically tortured. None of the thousands of experiments conducted on animals every year at universities are required by law.

You can join PETA in opposing these cruel and useless tests by taking action today:

Are Tests on Animals Legal?

Yes. U.S. law allows for animals to be burned, shocked, poisoned, isolated, starved, drowned, addicted to drugs, and brain-damaged. No experiment, no matter how painful or trivial, is prohibited—and painkillers are often not required. Even when alternatives to the use of animals are available, the law doesn’t require that they be used—and often, they aren’t.

How Does PETA Help Animals Used in Experiments?

PETA’s vivid demonstrations and undercover investigations alert the public to wasteful, cruel, and useless experiments on animals, often ones occurring right under their noses. We actively campaign to get animals out of laboratories—and win. Check out a list of our latest victories .

The PETA International Science Consortium Ltd. works with agencies around the world to reduce the number of animals used in tests. PETA’s scientists are at the forefront of humane and modern methods, promoting groundbreaking non-animal tests and eliminating requirements for experiments on animals by sharing existing research and data with companies and governments.

PETA scientists sat in as the U.S. Environmental Protection Agency made the historic announcement that it would end toxicity tests on mammals—something we’ve pushed the agency to do for nearly 20 years.

Which Cosmetics and Personal-Care Companies Don’t Conduct Tests on Animals?

Neither the U.S. Food and Drug Administration nor the U.S. Consumer Product Safety Commission requires that cosmetics be tested on animals. There are already sufficient safety data and many non-animal methods available to make animal testing obsolete for these products.

Thankfully, most cosmetics companies have already banned tests on animals as a result of PETA’s campaigns and consumer pressure. However, some sell products in countries where tests on animals are required. PETA’s searchable Global Beauty Without Bunnies list makes it easy to find cruelty-free companies that have committed to never testing their cosmetics or household cleaning products on animals—here or abroad.

PETA also works with large food and beverage companies to end the practice of testing ingredients on animals in order to make health claims about products. Dozens of companies have banned all tests on animals for this purpose. You can rest assured knowing that the delicious vegan foods you’ll find recommended in our Living section come from such companies.

What Percentage of Animal Tests Fail?

Studies published in prestigious medical journals have repeatedly shown that animal experimentation wastes precious resources and lives. More than 90% of basic research , most of which involves animals, fails to lead to treatments for humans. And more than 95% of new drugs that test safe and effective in animals go on to fail in human clinical trials. Yet around the world, millions of animals continue to be used in experiments and then killed.

History of Animal Testing and Animal-Free Medical Advances

Between 1900 and 2000, life expectancy in the U.S. increased from 47 to 77 years. Although animal experimenters are often credited with this progress, medical historians report that improved nutrition and sanitation as well as other behavioral and environmental factors—rather than anything learned from tormenting animals—are responsible for this increased longevity.

Epidemiological studies have led to some of the most important breakthroughs, including the discovery of the relationship between cholesterol and heart disease and between smoking and cancer, the development of X-rays, and the isolation of the AIDS virus.

While experiments on animals have been conducted during the course of some important discoveries, this doesn’t mean that they were vital to the discovery of human-health treatments or that the same discoveries wouldn’t have been made anyway without using animals.

Take a trip through time using PETA’s interactive timeline, “ Without Consent ,” to learn about almost 200 stories of twisted animal experiments from the past century.

Animal Testing Alternatives: Can Science Progress Without Tests on Animals?

Today—because experiments on animals are cruel and expensive and their results are generally inapplicable to humans—the world’s most forward-thinking scientists are developing and using methods for studying diseases and testing products that replace animals and are actually relevant to human health.

Alternatives to animal testing include sophisticated tests using human cells and tissues (also known as in vitro methods), organs-on-chips, advanced computer-modeling techniques (often referred to as in silico models), and studies with human volunteers. These and other non-animal methods are humane, and they aren’t hindered by species differences that make applying animal test results to humans difficult or impossible. Also, they usually take less time and money to complete.

Why Should Animal Testing Be Banned?

In addition to the many reasons listed above, testing on animals is wasteful, violent, unproductive, and speciesist . Animals are not ours to use for experiments. They have their own wants, interests, needs, and feelings—independent of what purpose they might serve humans. In short, they are their own people and they don’t consent to being tortured and killed in laboratories.

Human wellness is more likely to be advanced by devoting resources to the development of non-animal test methods, which have the potential to be cheaper, faster, and more relevant to our bodies and health.

Support PETA’s Efforts to Help Animals in Laboratories

PETA makes it easy to take action to help animals suffering in experiments. Check out the page below, which makes it quick and easy to urge experimenters to end tests on animals:

From PETA and executive producer Bill Maher, the new docuseries ‘The Failed Experiment’ exposes what most people don’t know about experiments on animals.

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Article Contents

Introduction, experimental design: initial steps, design of the animal experiment, experimental design: final considerations.

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Practical Aspects of Experimental Design in Animal Research

Paula D. Johnson, D.V.M., M.S., is Executive Director, Southwest Association for Education in Biomedical Research, University of Arizona, Tucson; David G. Besselsen, D.V.M., Ph.D., is Veterinary Specialist and Chief, Pathology Services, University Animal Care, University of Arizona, Tucson.

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Paula D. Johnson, David G. Besselsen, Practical Aspects of Experimental Design in Animal Research, ILAR Journal , Volume 43, Issue 4, 2002, Pages 202–206, https://doi.org/10.1093/ilar.43.4.202

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A brief overview is presented of the key steps involved in designing a research animal experiment, with reference to resources that specifically address each topic of discussion in more detail. After an idea for a research project is conceived, a thorough review of the literature and consultation with experts in that field are pursued to refine the problem statement and to assimilate background information that is necessary for the experimental design phase. A null and an alternate hypothesis that address the problem statement are then formulated, and only then is the specific design of the experiment developed. Likely the most critical step in designing animal experiments is the identification of the most appropriate animal model to address the experimental question being asked. Other practical considerations include defining the necessary control groups, randomly assigning animals to control/treatment groups, determining the number of animals needed per group, evaluating the logistics of the actual performance of the animal experiments, and identifying the most appropriate statistical analyses and potential collaborators experienced in the area of study. All of these factors are critical to designing an experiment that will generate scientifically valid and reproducible data, which should be considered the ultimate goal of any scientific investigation.

Experimental design is obviously a critical component of the success of any research project. If all aspects of experimental design are not thoroughly addressed, scientists may reach false conclusions and pursue avenues of research that waste considerable time and resources. It is therefore critical to design scientifically sound experiments and to follow standard laboratory practices while performing these experiments to generate valid reproducible data ( Bennett et al. 1990 ; Diamond 2001 ; Holmberg 1996 ; Larsson 2001 ; Sproull 1995 ; Weber and Skillings 2000 ; Webster 1985 ; Whitcom 2000 ). Data generated by this approach should be of sufficient quality for publication in well-respected peer-reviewed journals, the major form of widespread communication and archiving experimental data in research. This article provides a brief overview of the steps involved in the design of animal experiments and some practical information that should also be considered during this process.

Literature Search

A thorough search of the scientific literature must be performed to determine what is known about the focus of the study. The search should include current and past journal articles and textbooks, as well as information available via the internet. Journal searches can be performed in any number of appropriate journal databases or indexes (e.g., MEDLINE, TOXLINE, PUBMED, NCBI, AGRICOLA). The goals of the literature search are to learn of pertinent studies and methods, identify appropriate animal models, and eliminate unnecessary duplication of research. The “3Rs” of animal research ( Russell and Burch 1959 ) should also be considered at this stage: reduction of animal numbers, refinement of methods, and replacement of animals by viable nonanimal alternatives when these exist. The literature search is also an important component of an institutional animal care and use committee (IACUC 1 ) protocol submission to provide evidence that the project is not duplicative, that alternatives to the use of animals are not available, and that potentially painful procedures are justified.

Scientific Method

The core aspect of experimental design is the scientific method ( Barrow 1991 ; Kuhn 1962 ; Lawson 2002 ; Wilson 1952 ). The scientific method consists of four basic steps: (1) observation and description of a scientific phenomena, (2) formulation of the problem statement and hypothesis, (3) use of the hypothesis to predict the results of new observations, and (4) the performance of methods or procedures to test the hypothesis.

Problem Statement, Objectives, and Hypotheses

It is critical to define the problem statement, objectives, and hypotheses clearly. The problem statement should include the issue that will be addressed experimentally and its significance (e.g., potential application to human or animal health, improved understanding of biological processes). Objectives should be stated in a general description of the overall goals for the proposed experiments and the specific questions being addressed. Hypotheses should include two distinct and clearly defined outcomes for each proposed experiment (e.g., a null and an alternate hypothesis). These outcomes may be thought of as the two experimental answers to the specific question being investigated: The null hypothesis is defined as no difference between experimental groups, and the alternate hypothesis is defined as a real difference between experimental groups. Development of a clearly stated problem statement and the hypotheses are necessary to proceed to the next stage of the experimental design process, although they obviously can (and likely will) be modified as the process continues. Examples of a problem statement and various types of hypotheses follow:

Problem statement: Which diet causes more weight gain in rats: diet A or diet B?

Null hypothesis: Groups are expected to show the same results (e.g., rats on diet A will gain the same amount of weight as rats on diet B).

Alternate hypothesis: Experimental groups are expected to show different results (e.g., rats will gain more weight on diet A than diet B, or vice versa).

Nontestable hypothesis: A result cannot be easily defined or interpreted (e.g., rats on diet A will look better than rats on diet B). What does “better” mean? Its definition must be clearly stated to create a testable hypothesis.

Identification of Animal Model

In choosing the most appropriate animal models for proposed experiments, we offer the following recommendations: (1) Use the lowest animal on the phylogenic scale (in accordance with replacement, one of the 3Rs). (2) Use animals that have the species- and/or strain-specific characteristics desirable or required for the specific study proposed. (3) Consider the costs associated with acquiring and maintaining the animal model during the period of experimentation. (4) Perform a thorough literature search, network with colleagues within the selected field of study, and/or contact commercial vendors or government-supported repositories of animal models to identify a potential source of the animal model. (5) Consult with laboratory animal veterinarians before final determination of the animal model.

Identification of Potential Collaborators

The procedures required to carry out the experiments will determine what, if any, additional expertise is needed. It is important to identify and consult with potential collaborators at the beginning of project development to determine who will be working on the project and in what capacity (e.g., as coinvestigators, consultants, or technical support staff). Collaborator input into the logistics and design of the experiments and proper sample acquisition are critical to ensure the validity of the data generated. Core facilities at larger research institutions provide many services that involve highly technical procedures or require expensive equipment. Identification of existing core facilities can often lead to the development of a list of potential intramural collaborators.

Research Plan

A description of the experimental manipulations required to address the problem statement, objectives, and hypotheses should be carefully devised and documented ( Keppel 1991 ). This description should specify the experimental variables that are to be manipulated, suitable test parameters that accurately assess the effects of experimental variable manipulation, and the most appropriate methods for sample acquisition and generation of the test data. The overall practicality of the project as well as the time frame for data collection and evaluation are determined at this stage in the development process.

Practical issues that may need to be addressed include the lifespan of the animal model (for chronic studies), the anticipated progression of disease in that model (to determine appropriate time points for evaluation), the amount of personnel time available for the project, and the costs associated with performing the experiments ( De Boer et al. 1975 ). If the animals are to receive chemical or biological treatments, an appropriate method for administration must be identified (e.g., per os via the diet or in drinking water [soluble substances only], by osmotic pump, or by injection). Known or potential hazards must also be identified, and appropriate precautions to minimize risk from these hazards must be incorporated into the plan. All experimental procedures should be detailed through standard operating procedures, a requirement of good laboratory practice standards ( EPA 1989 ; FDA 1987 ).

Finally, the methods to be used for data analysis should be determined. If statistical analysis is required to document a difference between experimental groups, the appropriate statistical tests should be identified during the design stage. A conclusion will be drawn subsequently from the analysis of the data with the initial question answered and/or the hypotheses accepted or rejected. This process will ultimately lead to new questions and hypotheses being formulated, or ideas as to how to improve the experimental design.

Experimental Unit

The entity under study is the experimental unit, which could be an individual animal or a group. For example, an individual rat is considered the experimental unit when a drug therapy or surgical procedure is being tested, but an entire litter of rats is the experimental unit when an environmental teratogen is being tested. For purposes of estimating error of variance, or standard error for statistical analysis, it is necessary to consider the experimental unit ( Weber and Skillings 2000 ). Many excellent sources provide discussions of the types of experimental units and their appropriateness ( Dean and Voss 1999 ; Festing and Altman 2002 ; Keppel 1991 ; Wu and Hamada 2000 ).

N Factor: Experimental Group Size

The assignment of an appropriate number of animals to each group is critical. Although formulas to determine the proper number of animals can be found in standard statistical texts, we recommend consulting a statistician to ensure appropriate experimental design for the generation of statistically significant results ( Zolman 1993 ). Indeed, the number of animals assigned to each experimental group is often determined by the particular statistical test on the basis of the anticipated magnitude of difference between the expected outcomes for each group. The number of animals that can be grouped in standard cages is a practical consideration for determining experimental group size. For example, standard 71 sq in (460 sq cm) polycarbonate shoebox cages can house up to four adult mice, so group sizes that are divisible by four will maximize group size and minimize per diem costs.

A plethora of variables (e.g., genetic, environmental, infectious agents) can potentially affect the outcome of studies performed with animals. It is therefore critical to use control animals to minimize the impact of these extraneous variables or to recognize the possible presence of unwanted variables. In general, each individual experiment should use control groups of animals that are contrasted directly to the experimental groups of animals. Multiple types of controls include positive, negative, sham, vehicle, and comparative.

Positive Controls

In positive control groups, changes are expected. The positive control acts as a standard against which to measure difference in severity among experimental groups. An example of a positive control is a toxin administered to an animal, which results in reproducible physiological alterations or lesions. New treatments can then be used in experimental groups to determine whether these alterations may be prevented or cured. Positive controls are also used to demonstrate that a response can be detected, thereby providing some quality control on the experimental methods.

Negative Controls

Negative controls are expected to produce no change from the normal state. In the example above, the negative control would consist of animals not treated with the toxin. The purpose of the negative control is to ensure that an unknown variable is not adversely affecting the animals in the experiment, which might result in a false-positive conclusion.

Sham Controls

A sham control is used to mimic a procedure or treatment without the actual use of the procedure or test substance. A placebo is an example of a sham control used in pharmaceutical studies ( Spector 2002 ). Another example is the surgical implantation of “X” into the abdominal cavity. The treated animals would have X implanted, whereas the sham control animals would have the same surgical procedure with the abdominal cavity opened, as with the treated animals, but without having the X implanted.

Vehicle Controls

A vehicle control is used in studies in which a substance (e.g., saline or mineral oil) is used as a vehicle for a solution of the experimental compound. In a vehicle control, the supposedly innocuous substance is used alone, administered in the same manner in which it will be used with the experimental compound. When compared with the untreated control, the vehicle control will determine whether the vehicle alone causes any effects.

Comparative Controls

A comparative control is often a positive control with a known treatment that is used for a direct comparison to a different treatment. For example, when evaluating a new chemopreventive drug regime in an animal model of cancer, one would want to compare this regime to the chemopreventive drug regime currently considered “accepted practice” to determine whether the new regime improves cancer prevention in that model.

Randomization

Randomization of the animals assigned to different experimental groups must be achieved to ensure that underlying variables do not result in skewed data for each experimental group. To achieve randomization, it is necessary to begin by defining the population. A homogeneous population consists of animals that are considered to share some characteristics (e.g., age, sex, weight, breed, strain). A heterogeneous population consists of animals that may not be the same but may have some common feature. Generally, the better the definition of the group, the less variable the experimental data, although the results may be less pertinent to large broad populations. Methods commonly used to achieve randomization include the following ( Zolman 1993 ):

Identifying each animal with a unique identification number, then drawing numbers “out of a hat” and randomly assigning them in a logical fashion to different groups. For example, the first drawn number is assigned to group 1, the second to group 2, the third to group 1, the fourth to group 2, and so forth. Dice or cards may also be used to randomly assign animals to experimental groups.

Using random number tables or computer-generated numbers/sampling to achieve randomization.

Experimental Protocol Approval

Animal experimentation requires IACUC approval of an animal care and use protocol if the species used are covered under the Animal Welfare Act (regardless of funding source), the research is supported by the National Institutes of Health and involves the use of vertebrate species, or the animal care program is accredited by the Association for the Assessment and Accreditation of Laboratory Animal Care International ( Silverman et al. 2000 ). In practice, virtually all animal experiments require IACUC approval, which entails full and accurate completion of appropriate protocol forms for submission to the IACUC, followed by clarification or necessary modification of any procedures the IACUC requires. Approval must be obtained before the animal purchase or experimentation and is required before submission of a grant proposal by some funding agencies. If the research involves hazardous materials, then protocol approval from other intramural oversight committees or departments may also be required (e.g., a Biosafety Committee if infectious agents or recombinant DNA are to be used, or a Radiation Safety Committee if radioisotopes or irradiation are to be used).

Animal welfare regulations and Public Health Service policy mandate that individuals caring for or using research animals must be appropriately trained. Specifically, all personnel involved in a research project must be appropriately qualified and/or trained in the methods they will be performing for that project. The institution where the research is being performed is responsible for ensuring this training, although the actual training may occur elsewhere.

Pilot Studies

Pilot studies use a small number of animals to generate preliminary data and/or allow the procedures and techniques to be solidified and “perfected” before large-scale experimentation. These studies are commonly used with new procedures or when new compounds are tested. Preliminary data are essential to show evidence supporting the rationale of a proposal to a funding agency, thereby increasing the probability of funding for the proposal. All pilot projects must have IACUC approval, as for any animal experiment. As soon as the pilot study is completed, the IACUC representative will either give the indication to proceed to a full study or will indicate that the experimental manipulations and/or hypotheses need to be modified and evaluated by additional pilot studies.

Data Entry and Analysis

The researcher has the ultimate responsibility for collecting, entering, and analyzing the data correctly. When dealing with large volumes of data, it is especially easy for data entry errors to occur (e.g., group identifications switched, animal identifications transposed). Quality assurance procedures to identify data entry errors should be developed and incorporated into the experimental design before data analysis. This process can be accomplished by directly comparing raw (original) data for individual animals with the data entered into the computer or with compiled data for the group as a whole (to identify potential “outliers,” or data that deviates significantly from the rest of the members of a group). The analysis of the data varies depending on the type of project and the statistics required to evaluate it. Because this topic is beyond the scope of this article, we refer the reader to the many outstanding books and articles on statistical analysis ( Cobb 1998 ; Cox and Reid 2000 ; Dean and Voss 1999 ; Festing and Altman 2002 ; Lemons et al. 1997 ; Pickvance 2001 ; Wasserman and Kutner 1985 ; Wilson and Natale 2001 ; Wu and Hamada 2000 ).

Detection of flaws, in the developing or final experimental design is often achieved by several levels of review that are applicable to animal experimentation. For example, grant funding agencies and the IACUC provide input into the content and design of animal experiments during their review processes and may also serve as advisory consultants before submission of the grant proposal or animal care and use protocol. Scientific peers and the scientific literature also provide invaluable information applicable to experimental design, and these resources should be consulted throughout the experimental design process. Finally, scientific peer-reviewed journals provide a final critical evaluation of the soundness of the experimental design. The overall quality of the experimental data is evaluated and a determination is made as to whether it is worthy of publication. Obviously, discovering major experimental design deficiencies during manuscript peer review is not desirable. Therefore, pursuit of scientific peer review throughout the experimental design process should be exercised routinely to ensure the generation of valid, reproducible, and publishable data.

The steps listed below comprise a practical sequence for designing and conducting scientific studies. We recommend that investigators

Conduct a complete literature review and consult experts who have experience with the techniques proposed in an effort to become thoroughly familiar with the topic before beginning the experimental design process.

Ask a specific question and/or formulate an appropriate hypothesis. Then design the experiments to specifically address that problem/question.

Consult a biostatistician during the design phase of the project, not after performing the experiments.

Choose proper controls to ensure that only the variable of interest is evaluated. More than one control is frequently required.

Start with a small pilot project to generate preliminary data and work out procedures and techniques. Then proceed to larger scale experiments to generate statistical significance.

Modify original question and procedures, ask new questions, and begin again.

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Abbreviation used in this article: IACUC, institutional animal care and use committee.

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National Research Council (US) Committee for the Update of the Guide for the Care and Use of Laboratory Animals. Guide for the Care and Use of Laboratory Animals. 8th edition. Washington (DC): National Academies Press (US); 2011.

Guide for the Care and Use of Laboratory Animals. 8th edition.

• Hardcopy Version at National Academies Press

1 Key Concepts

This edition of the Guide for the Care and Use of Laboratory Animals (the Guide ) strongly affirms the principle that all who care for, use, or produce animals for research, testing, or teaching must assume responsibility for their well-being. The Guide is created by scientists and veterinarians for scientists and veterinarians to uphold the scientific rigor and integrity of biomedical research with laboratory animals as expected by their colleagues and society at large.

The Guide plays an important role in decision making regarding the use of vertebrate laboratory animals because it establishes the minimum ethical, practice, and care standards for researchers and their institutions. The use of laboratory animals in research, teaching, testing, and production is also governed or affected by various federal and local laws, regulations, and standards; for example, in the United States the Animal Welfare Act ( AWA 1990 ) and Regulations (PL 89-544; USDA 1985 ) and/or Public Health Service (PHS) Policy ( PHS 2002 ) may apply. Compliance with these laws, regulations, policies, and standards (or subsequent revised versions) in the establishment and implementation of a program of animal care and use is discussed in Chapter 2 .

Taken together, the practical effect of these laws, regulations, and policies is to establish a system of self-regulation and regulatory oversight that binds researchers and institutions using animals. Both researchers and institutions have affirmative duties of humane care and use that are supported by practical, ethical, and scientific principles. This system of self-regulation establishes a rigorous program of animal care and use and provides flexibility in fulfilling the responsibility to provide humane care. The specific scope and nature of this responsibility can vary based on the scientific discipline, nature of the animal use, and species involved, but because it affects animal care and use in every situation this responsibility requires that producers, teachers, researchers, and institutions carry out purposeful analyses of proposed uses of laboratory animals. The Guide is central to these analyses and to the development of a program in which humane care is incorporated into all aspects of laboratory animal care and use.

• APPLICABILITY AND GOALS

In the Guide, laboratory animals (also referred to as animals ) are generally defined as any vertebrate animal (i.e., traditional laboratory animals, agricultural animals, wildlife, and aquatic species) produced for or used in research, testing, or teaching. Animal use is defined as the proper care, use, and humane treatment of laboratory animals produced for or used in research, testing, or teaching.

Laboratory animals or animals: Any vertebrate animal (e.g., traditional laboratory animals, agricultural animals, wildlife, and aquatic species) produced for or used in research, testing, or teaching.

When appropriate, considerations or specific emphases for agricultural animals and nontraditional species are presented. The Guide does not address in detail agricultural animals used in production, agricultural research or teaching, wildlife and aquatic species studied in natural settings, or invertebrate animals (e.g., cephalopods) used in research, but establishes general principles and ethical considerations that are also applicable to these species and situations. References provide the reader with additional resources, and supplemental information on breeding, care, management, and use of selected laboratory animal species is available in other publications prepared by the Institute for Laboratory Animal Research (ILAR) and other organizations ( Appendix A ).

Animal use: The proper care, use, and humane treatment of laboratory animals produced for or used in research, testing, or teaching.

The goal of the Guide is to promote the humane care and use of laboratory animals by providing information that will enhance animal well-being, the quality of research, and the advancement of scientific knowledge that is relevant to both humans and animals. The Committee recognizes that the use of different species in research is expanding and that researchers and institutions will face new and unique challenges in determining how to apply the Guide in these situations. In making such determinations, it is important to keep in mind that the Guide is intended to provide information to assist researchers, institutional animal care and use committees (IACUCs), veterinarians, and other stakeholders in ensuring the implementation of effective and appropriate animal care and use programs that are based on humane care. Throughout the Guide , scientists and institutions are encouraged to give careful and deliberate thought to the decision to use animals, taking into consideration the contribution that such use will make to new knowledge, ethical concerns, and the availability of alternatives to animal use ( NRC 1992 ). A practical strategy for decision making, the “Three Rs” (Replacement, Reduction, and Refinement) approach, is discussed in more detail below. Institutions should use the recommendations in the Guide as a foundation for the development of a comprehensive animal care and use program and a process for continually improving this program.

• INTENDED AUDIENCES AND USES OF THE GUIDE

The Guide is intended for a wide and diverse audience, including

• the scientific community
• administrators
• veterinarians
• educators and trainers
• producers of laboratory animals
• accreditation bodies
• the public.

The Guide is meant to be read by the user in its entirety, as there are many concepts throughout that may be helpful. Individual sections will be particularly relevant to certain users, and it is expected that the reader will explore in more detail the references provided (including those in Appendix A ) on topics of interest.

Members of the scientific community (investigators and other animal users) will find Chapters 1 and 2 (and portions of Chapter 4 ) of the Guide useful for their interactions with the IACUC, attending veterinarian, and administrators regarding animal care as well as the preparation of animal care and use protocols. Scientific review committees and journal editors may choose to refer to multiple sections of the Guide to determine whether scientists contributing proposals and manuscripts have met the appropriate standards in their planned use of animals. The Guide can assist IACUCs and administrators in protocol review, assessment, and oversight of an animal care and use program. Veterinarians should find Chapters 3 through 5 valuable for their oversight and support of animal care and use. Educators and trainers can use the Guide as a document to assess both the scope and adequacy of training programs supported by the institution. Accreditation bodies will find the Guide useful for evaluating many areas of animal care and use programs not subject to strict engineering standards (see definition below). Finally, members of the public should feel assured that adherence to the Guide will ensure humane care and use of laboratory animals.

Readers are reminded that the Guide is used by a diverse group of national and international institutions and organizations, many of which are covered by neither the Animal Welfare Act nor the PHS Policy. The Guide uses some terminology that is both defined by US statute and denotes a general concept (e.g., “attending veterinarian,” “adequate veterinary care,” and “institutional official”). Even if these terms are not consistent with those used by non-US institutions, the underlying principles can still be applied. In all instances where Guide recommendations are different from applicable legal or policy requirements, the higher standard should apply.

• ETHICS AND ANIMAL USE

The decision to use animals in research requires critical thought, judgment, and analysis. Using animals in research is a privilege granted by society to the research community with the expectation that such use will provide either significant new knowledge or lead to improvement in human and/or animal well-being ( McCarthy 1999 ; Perry 2007 ). It is a trust that mandates responsible and humane care and use of these animals. The Guide endorses the responsibilities of investigators as stated in the U.S. Government Principles for Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training ( IRAC 1985 ; see Appendix B ). These principles direct the research community to accept responsibility for the care and use of animals during all phases of the research effort. Other government agencies and professional organizations have published similar principles ( NASA 2008 ; NCB 2005 ; NIH 2006 , 2007 ; for additional references see Appendix A ). Ethical considerations discussed here and in other sections of the Guide should serve as a starting point; readers are encouraged to go beyond these provisions. In certain situations, special considerations will arise during protocol review and planning; several of these situations are discussed in more detail in Chapter 2 .

• THE THREE Rs

The Three Rs represent a practical method for implementation of the principles described above. In 1959, W.M.S. Russell and R.L. Burch published a practical strategy of replacement, refinement, and reduction—referred to as the Three Rs—for researchers to apply when considering experimental design in laboratory animal research ( Russell and Burch 1959 ). Over the years, the Three Rs have become an internationally accepted approach for researchers to apply when deciding to use animals in research and in designing humane animal research studies.

Replacement refers to methods that avoid using animals. The term includes absolute replacements (i.e., replacing animals with inanimate systems such as computer programs) as well as relative replacements (i.e., replacing animals such as vertebrates with animals that are lower on the phylogenetic scale).

Refinement refers to modifications of husbandry or experimental procedures to enhance animal well-being and minimize or eliminate pain and distress. While institutions and investigators should take all reasonable measures to eliminate pain and distress through refinement, IACUCs should understand that with some types of studies there may be either unforeseen or intended experimental outcomes that produce pain. These outcomes may or may not be eliminated based on the goals of the study.

Reduction involves strategies for obtaining comparable levels of information from the use of fewer animals or for maximizing the information obtained from a given number of animals (without increasing pain or distress) so that in the long run fewer animals are needed to acquire the same scientific information. This approach relies on an analysis of experimental design, applications of newer technologies, the use of appropriate statistical methods, and control of environmentally related variability in animal housing and study areas (see Appendix A ).

Refinement and reduction goals should be balanced on a case-by-case basis. Principal investigators are strongly discouraged from advocating animal reuse as a reduction strategy, and reduction should not be a rationale for reusing an animal or animals that have already undergone experimental procedures especially if the well-being of the animals would be compromised. Studies that may result in severe or chronic pain or significant alterations in the animals’ ability to maintain normal physiology, or adequately respond to stressors, should include descriptions of appropriate humane endpoints or provide science-based justification for not using a particular, commonly accepted humane endpoint. Veterinary consultation must occur when pain or distress is beyond the level anticipated in the protocol description or when interventional control is not possible.

• KEY TERMS USED IN THE GUIDE

The Committee for the Update of the Guide believes that the terms set out below are important for a full understanding of the Guide . Accordingly, we have defined these terms and concepts to provide users of the Guide with additional assistance in implementing their responsibilities.

Humane Care

Humane care means those actions taken to ensure that laboratory animals are treated according to high ethical and scientific standards. Implementation of a humane care program, and creation of a laboratory environment in which humane care and respect for animals are valued and encouraged, underlies the core requirements of the Guide and the system of self-regulation it supports ( Klein and Bayne 2007 ).

Animal Care and Use Program

The animal care and use program (the Program) means the policies, procedures, standards, organizational structure, staffing, facilities, and practices put into place by an institution to achieve the humane care and use of animals in the laboratory and throughout the institution. It includes the establishment and support of an IACUC or equivalent ethical oversight committee and the maintenance of an environment in which the IACUC can function successfully to carry out its responsibilities under the Guide and applicable laws and policies. Chapter 2 provides a more expansive discussion of the importance of the Guide and its application to animal care and use programs.

Engineering, Performance, and Practice Standards

Engineering standard means a standard or guideline that specifies in detail a method, technology, or technique for achieving a desired outcome; it does not provide for modification in the event that acceptable alternative methods are available or unusual circumstances arise. Engineering standards are prescriptive and provide limited flexibility for implementation. However, an engineering standard can be useful to establish a baseline and is relatively easy to use in evaluating compliance.

Performance standard means a standard or guideline that, while describing a desired outcome, provides flexibility in achieving this outcome by granting discretion to those responsible for managing the animal care and use program, the researcher, and the IACUC. The performance approach requires professional input, sound judgment, and a team approach to achieve specific goals. It is essential that the desired outcomes and/or goals be clearly defined and appropriate performance measures regularly monitored in order to verify the success of the process. Performance standards can be advantageous because they accommodate the consideration of many variables (such as the species and previous history of the animals, facilities, staff expertise, and research goals) so that implementation can be best tailored to meet the recommendations in the Guide .

Ideally, engineering and performance standards are balanced, setting a target for optimal practices, management, and operations while encouraging flexibility and judgment, if appropriate, based on individual situations ( Gonder et al. 2001 ).

Scientists, veterinarians, technicians, and others have extensive experience and information covering many of the topics discussed in the Guide . For topics on which information is insufficient or incomplete, sustained research into improved methods of laboratory animal management, care, and use is needed for the continued evaluation and improvement of performance and engineering standards.

Practice standard means the application of professional judgment by qualified, experienced individuals to a task or process over time, an approach that has been demonstrated to benefit or enhance animal care and use. Professional judgment comes from information in the peer-reviewed scientific literature and textbooks and, as in many other disciplines, from time-proven experiences in the field (for additional information see Chapter 2 ). In the absence of published scientific literature or other definitive sources, where experience has demonstrated that a particular practice improves animal care and use, practice standards have been used in determining appropriate recommendations in the Guide . In most situations, the Guide is intended to provide flexibility so that institutions can modify practices and procedures with changing conditions and new information.

• POLICIES, PRINCIPLES, AND PROCEDURES

Policies commonly derive from a public agency or private entity. They are generally practical statements of collective wisdom, convention, or management direction that are internal to the entity. However, policies may assume broader force when they become the means by which an implementing agency interprets existing statutes (e.g., PHS Policy). Principles are broader in their scope and intended application, and are accepted generalizations about a topic that are frequently endorsed by many and diverse organizations (e.g., the U.S. Government Principles). Procedures (often called “operating procedures” or “standard operating procedures”) are typically detailed, step-by-step processes meant to ensure the consistent application of institutional practices. Establishing standard operating procedures can assist an institution in complying with regulations, policies, and principles as well as with day-to-day operations and management.

• MUST, SHOULD, AND MAY

Must indicates actions that the Committee for the Update of the Guide considers imperative and mandatory duty or requirement for providing humane animal care and use. Should indicates a strong recommendation for achieving a goal; however, the Committee recognizes that individual circumstances might justify an alternative strategy. May indicates a suggestion to be considered.

The Guide is written in general terms so that its recommendations can be applied in diverse institutions and settings that produce or use animals for research, teaching, and testing. This approach requires that users, IACUCs, veterinarians, and producers apply professional judgment in making specific decisions regarding animal care and use. Because the Guide is written in general terms, IACUCs have a key role in interpretation, implementation, oversight, and evaluation of institutional animal care and use programs.

• AWA [Animal Welfare Act] Animal Welfare Act. PL (Public Law) 89-544. 1990. [accessed January 14, 2010]. Available at www ​.nal.usda.gov/awic/legislat/awa.htm .
• Gonder JC, Smeby RR, Wolfle TL. Performance Standards and Animal Welfare: Definition, Application and Assessment, Parts I and II. Greenbelt MD: Scientists Center for Animal Welfare; 2001.
• IRAC [Interagency Research Animal Committee] U.S. Government Principles for Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training. Federal Register, May 20, 1985. Washington: Office of Science and Technology Policy; 1985. [accessed May 10, 2010]. Available at http://oacu ​.od.nih.gov ​/regs/USGovtPrncpl.htm .
• Klein HJ, Bayne KA. Establishing a culture of care, conscience, and responsibility: Addressing the improvement of scientific discovery and animal welfare through science-based performance standards. ILAR J. 2007; 48 :3–11. [ PubMed : 17170491 ]
• McCarthy CR. Bioethics of laboratory animal research. ILAR J. 1999; 40 :1–37.
• NASA [National Aeronautics and Space Administration] NASA Principles for the Ethical Care and Use of Animals. NPR 8910.1B-Appendix A. May 28. 2008. [accessed May 10, 2010]. Available at http://nodis3 ​.gsfc.nasa ​.gov/displayDir.cfm?t ​=NPDandc=8910ands=1B .
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• NIH [National Institutes of Health] Memorandum of Understanding Between the Office of Laboratory Animal Welfare, National Institutes of Health, US Department of Health and Human Services and the Office of Research Oversight and the Office of Research and Development, Veterans Health Administration, US Department of Veterans Affairs Concerning Laboratory Animal Welfare. November 2007. Bethesda: Office of Extramural Research, NIH; 2007. Available at http://grants ​.nih.gov ​/grants/olaw/references ​/mou_olaw_va_2007_11.htm .
• NIH. Memorandum of Understanding Among the Animal and Plant Health Inspection Service USDA and the Food and Drug Administration, US Department of Health and Human Services and the National Institutes of Health Concerning Laboratory Animal Welfare. March 1, 2006. Bethesda: Office of Extramural Research, NIH; 2006. Available at http://grants ​.nih.gov ​/grants/olaw/references/finalmou.htm .
• NRC [National Research Council] Report on Responsible Science. Washington: National Academy Press; 1992.
• Perry P. The ethics of animal research: A UK perspective. ILAR J. 2007; 48 :42–46. [ PubMed : 17170495 ]
• PHS [Public Health Service] Public Health Service Policy on Humane Care and Use of Laboratory Animals. Publication of the Department of Health and Human Services, National Institutes of Health, Office of Laboratory Animal Welfare. 2002. [accessed June 9, 2010]. Available at http://grants ​.nih.gov ​/grants/olaw/references/phspol.htm .
• Russell WMS, Burch RL. The Principles of Humane Experimental Technique. London: Methuen and Co; 1959. [Reissued: 1992, Universities Federation for Animal Welfare, Herts, UK]
• USDA [US Department of Agriculture] 9 CFR 1A. (Title 9, Chapter 1, Subchapter A): Animal Welfare. 1985. [accessed January 14, 2010]. Available at http://ecfr ​.gpoaccess ​.gov/cgi/t/text/text-idx?sid ​=8314313bd7adf2c9f1964e2d82a88d92andc=ecfrandtpl= ​/ecfrbrowse ​/Title09/9cfrv1_02.tpl .
• Cite this Page National Research Council (US) Committee for the Update of the Guide for the Care and Use of Laboratory Animals. Guide for the Care and Use of Laboratory Animals. 8th edition. Washington (DC): National Academies Press (US); 2011. 1, Key Concepts.
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The city beautiful movement, 1890–1920.

• John D. Fairfield John D. Fairfield Department of History, Xavier University
• https://doi.org/10.1093/acrefore/9780199329175.013.558
• Published online: 26 April 2018

The City Beautiful movement arose in the 1890s in response to the accumulating dirt and disorder in industrial cities, which threatened economic efficiency and social peace. City Beautiful advocates believed that better sanitation, improved circulation of traffic, monumental civic centers, parks, parkways, public spaces, civic art, and the reduction of outdoor advertising would make cities throughout the United States more profitable and harmonious. Engaging architects and planners, businessmen and professionals, and social reformers and journalists, the City Beautiful movement expressed a boosterish desire for landscape beauty and civic grandeur, but also raised aspirations for a more humane and functional city. “Mean streets make mean people,” wrote the movement’s publicist and leading theorist, Charles Mulford Robinson, encapsulating the belief in positive environmentalism that drove the movement. Combining the parks and boulevards of landscape architect Frederick Law Olmsted with the neoclassical architecture of Daniel H. Burnham’s White City at the Chicago’s World Columbian Exposition in 1893, the City Beautiful movement also encouraged a view of the metropolis as a delicate organism that could be improved by bold, comprehensive planning. Two organizations, the American Park and Outdoor Art Association (founded in 1897) and the American League for Civic Improvements (founded in 1900), provided the movement with a national presence. But the movement also depended on the work of civic-minded women and men in nearly 2,500 municipal improvement associations scattered across the nation. Reaching its zenith in Burnham’s remaking of Washington, D.C., and his coauthored Plan of Chicago (1909), the movement slowly declined in favor of the “City Efficient” and a more technocratic city-planning profession. Aside from a legacy of still-treasured urban spaces and structures, the City Beautiful movement contributed to a range of urban reforms, from civic education and municipal housekeeping to city planning and regionalism.

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Estimating the global warming potential of animal waste-based organic liquid fertilizer for urban hydroponic farms.

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• Published: 02 September 2024

An orally administered glucose-responsive polymeric complex for high-efficiency and safe delivery of insulin in mice and pigs

• Kangfan Ji 1 , 2 ,
• Xiangqian Wei 1 , 2 ,
• Anna R. Kahkoska 3 ,
• Juan Zhang 1 , 2 ,
• Yang Zhang 1 , 2 ,
• Jianchang Xu 1 , 2 ,
• Xinwei Wei 1 , 2 ,
• Wei Liu 1 , 2 ,
• Yanfang Wang 1 , 2 ,
• Yuejun Yao 1 , 2 ,
• Xuehui Huang 1 , 2 ,
• Shaoqian Mei 1 , 2 ,
• Yun Liu 1 , 2 ,
• Shiqi Wang 1 , 2 ,
• Zhengjie Zhao 1 , 2 ,
• Ziyi Lu 1 , 2 ,
• Jiahuan You 1 , 2 ,
• Guangzheng Xu 1 , 2 ,
• Youqing Shen   ORCID: orcid.org/0000-0003-1837-7976 4 ,
• John. B. Buse   ORCID: orcid.org/0000-0002-9723-3876 5 ,
• Jinqiang Wang   ORCID: orcid.org/0000-0002-0048-838X 1 , 2 , 6 , 7 &
• Zhen Gu   ORCID: orcid.org/0000-0003-2947-4456 1 , 2 , 6 , 8 , 9 , 10 , 11  

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Contrary to current insulin formulations, endogenous insulin has direct access to the portal vein, regulating glucose metabolism in the liver with minimal hypoglycaemia. Here we report the synthesis of an amphiphilic diblock copolymer comprising a glucose-responsive positively charged segment and polycarboxybetaine. The mixing of this polymer with insulin facilitates the formation of worm-like micelles, achieving highly efficient absorption by the gastrointestinal tract and the creation of a glucose-responsive reservoir in the liver. Under hyperglycaemic conditions, the polymer triggers a rapid release of insulin, establishing a portal-to-peripheral insulin gradient—similarly to endogenous insulin—for the safe regulation of blood glucose. This insulin formulation exhibits a dose-dependent blood-glucose-regulating effect in a streptozotocin-induced mouse model of type 1 diabetes and controls the blood glucose at normoglycaemia for one day in non-obese diabetic mice. In addition, the formulation demonstrates a blood-glucose-lowering effect for one day in a pig model of type 1 diabetes without observable hypoglycaemia, showing promise for the safe and effective management of type 1 diabetes.

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Acknowledgements

This work was supported by grants from the National Key R&D Program of China (2022YFE0202200, J.W.), JDRF (2-SRA-2021-1064-M-B, Z.G.; 2-SRA-2022-1159-M-B, J.W.), the Key Project of Science and Technology Commission of Zhejiang Province (2024C03083, Z.G.; 2024C03085, J.W.), Zhejiang University’s start-up packages and the Starry Night Science Fund at Shanghai institute for Advanced Study of Zhejiang University (SN-ZJU-SIAS-009, J.W.). A.R.K. is supported by the National Center for Advancing Translational Sciences, National Institutes of Health (KL2TR002490, J.W.). The project was supported by the Clinical and Translational Science Award program of the National Center for Advancing Translational Science, National Institutes of Health (UL1TR002489, J.W.). We appreciate the help from J. Pan and D. Wu of the Research and Service Center (College of Pharmaceutical Science, Zhejiang University) for technical support, G. Z. and Y. Zhang (Cryo-EM centre, Zhejiang University) for processing the samples for electron microscopy and D. Xu, M. Zhang, S. Xiong and D. Chen (Disease Simulation and Animal Model Platform of Liangzhu Laboratory) for taking care of the minipigs.

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Kangfan Ji, Xiangqian Wei, Juan Zhang, Yang Zhang, Jianchang Xu, Xinwei Wei, Wei Liu, Yanfang Wang, Yuejun Yao, Xuehui Huang, Shaoqian Mei, Yun Liu, Shiqi Wang, Zhengjie Zhao, Ziyi Lu, Jiahuan You, Guangzheng Xu, Jinqiang Wang & Zhen Gu

Jinhua Institute of Zhejiang University, Jinhua, China

Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

Anna R. Kahkoska

Zhejiang Key Laboratory of Smart Biomaterials, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China

Youqing Shen

Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA

John. B. Buse

Key Laboratory of Advanced Drug Delivery Systems of Zhejiang Province, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China

Jinqiang Wang & Zhen Gu

Department of Pharmacy, Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China

Jinqiang Wang

Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China

Liangzhu Laboratory, Hangzhou, China

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MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China

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Z.G., J.W., Y.S. and J.B.B. conceived and designed the study. K.J., Xiangqian Wei, J.Z., J.X., Xinwei Wei, Y.Z., W.L., Y.W., Y.Y., S.M. and Y.L. conducted experiments and obtained related data. X.H., S.W., Z.Z., J.Y., G.X. and Z.L. gave experimental operation and theoretical guidance of mice experiments. K.J., Xiangqian Wei, J.Z. and J.X. conducted minipigs experiments and provided theoretical support. Z.G., J.W., Y.S., K.J., J.Z., Xiangqian Wei, A.R.K., J.B.B. and J.X. analysed the data and wrote the paper.

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Correspondence to Jinqiang Wang or Zhen Gu .

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Extended data

Extended data fig. 1 bg-regulating effects in diabetic minipigs..

BG of diabetic minipigs treated with the insulin capsules (oral), the PPF-ins capsules (oral) or Lantus (s.c.). The insulin dose of oral formulations was set to 4.2 U/kg. The Lantus dose was set to 0.3 U/kg.

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Ji, K., Wei, X., Kahkoska, A.R. et al. An orally administered glucose-responsive polymeric complex for high-efficiency and safe delivery of insulin in mice and pigs. Nat. Nanotechnol. (2024). https://doi.org/10.1038/s41565-024-01764-5

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DOI : https://doi.org/10.1038/s41565-024-01764-5

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Hematopoietic Stem Cell Fates and the Cellular Hierarchy of Mammalian Hematopoiesis: from Transplantation Models to New Insights from in Situ Analyses

• Published: 02 September 2024

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• Dania Shaban 1 , 2 ,
• Nay Najm 1 , 2 ,
• Lucie Droin 1 , 2 &
• Anastasia Nijnik   ORCID: orcid.org/0000-0001-6048-4631 1 , 2  

Hematopoiesis is the process that generates the cells of the blood and immune system from hematopoietic stem and progenitor cells (HSPCs) and represents the system with the most rapid cell turnover in a mammalian organism. HSPC differentiation trajectories, their underlying molecular mechanisms, and their dysfunctions in hematologic disorders are the focal research questions of experimental hematology. While HSPC transplantations in murine models are the traditional tool in this research field, recent advances in genome editing and next generation sequencing resulted in the development of many fundamentally new approaches for the analyses of mammalian hematopoiesis in situ and at single cell resolution. The current review will cover many recent developments in this field in murine models, from the bulk lineage tracing studies of HSPC differentiation to the barcoding of individual HSPCs with Cre-recombinase, Sleeping Beauty transposase, or CRISPR/Cas9 tools, to map hematopoietic cell fates, together with their transcriptional and epigenetic states. We also address studies of the clonal dynamics of human hematopoiesis, from the tracing of HSPC clonal behaviours based on viral integration sites in gene therapy patients to the recent analyses of unperturbed human hematopoiesis based on naturally accrued mutations in either nuclear or mitochondrial genomes. Such studies are revolutionizing our understanding of HSPC biology and hematopoiesis both under homeostatic conditions and in the response to various forms of physiological stress, reveal the mechanisms responsible for the decline of hematopoietic function with age, and in the future may advance the understanding and management of the diverse disorders of hematopoiesis.

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AN was a Canada Research Chair in Hematopoiesis and Lymphocyte Development, funded by the Canadian Institutes of Health Research (CIHR) and The Leukemia & Lymphoma Society of Canada / La Société de Leucémie & Lymphome du Canada. DS was supported by the Canada Graduate Scholarship – Master’s Program (2022) and the Fonds de Recherche du Québec Santé (FRQS) – Doctoral Award (2023–2027). NN was supported by the Canada Graduate Scholarship – Master’s Program (2024).

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Dania Shaban, Nay Najm, Lucie Droin & Anastasia Nijnik

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Shaban, D., Najm, N., Droin, L. et al. Hematopoietic Stem Cell Fates and the Cellular Hierarchy of Mammalian Hematopoiesis: from Transplantation Models to New Insights from in Situ Analyses. Stem Cell Rev and Rep (2024). https://doi.org/10.1007/s12015-024-10782-8

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DOI : https://doi.org/10.1007/s12015-024-10782-8

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