Meredith Lee

How many animals are used in experiments each year?

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 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 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. Animals such as crabs, fish, frogs, octopuses and turtles are also 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 harmful experiments on animals.

Use our Animal Laboratory Public Search Tool to find information about facilities that use animals in experiments.

View a list of U.S. laboratories that use 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.

Back to top

Which animals are used in experiments?

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 into sanctuaries.

View Primates Used in Product and Drug Testing State Map  

Dogs Used in Experiments FAQ

Cosmetics Testing FAQ

Back to top

What kinds of experiments are animals used in?

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 rabies, HIV or tuberculosis) and not given pain relief or treatment of any kind 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 third-degree burns and forced to inhale smoke to study how humans might react to similar experiences.
  • 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 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. During this time, 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 even 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 anything to relieve their pain 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.

2019 Undercover Investigation

Back to top

What kinds of institutions use animals in experiments?

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

Back to top

Where do laboratories get the animals they use 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 purpose-bred animals are called Class A dealers and are licensed and inspected by the U.S. Department of Agriculture (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 State Pound Seizure Laws Map

Back to top

What is life like for animals in laboratories?

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 lonely and 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. Dogs, however, will often still seek human attention.

Animals in laboratories typically also watch (or hear) other animals suffering, including their own parents, siblings or babies. High levels of constant stress can cause them to mutilate themselves. This is especially true of primates. It is also not uncommon for animals to exhibit repetitive behaviors, such as constant pacing, rocking or vocalizing as a way to help relieve their anxiety.

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.

Back to top

What happens to the animals once an experiment is over?

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.

In some cases, animals die as a direct 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 after the experiments have ended.

Back to top

Aren’t there laws to protect animals used in experiments?

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, which is 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—rats, mice and birds bred for this purpose—are not counted in annual USDA statistics and are not afforded the minimal protections provided under the Animal Welfare Act. Animals such as fish, frogs, turtles, octopuses and crabs are also 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. 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 methods that could be used to replace experiments that harm animals. It also makes it difficult to determine the extent to which non-animal alternative methods are used.

Back to top

Why are animals still used in experiments?

The vast majority of experiments on animals are not required by government law or regulation, although certain animal tests are required by government agencies to assess the safety 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 dogsmice and ratsrabbitsbirds 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 tests and determining if they provide information necessary for assessing how safe a product or substance is for humans, or 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 some cases, a non-animal alternative must be formally validated—an expensive and lengthy process—in order to be accepted by government regulatory agencies, both in the U.S. and globally. 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.

Back to top

What are the alternatives to experiments on animals?

The world is 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 animal tests were developed decades ago and will always have severe limitations, these advanced non-animal methods represent the very latest techniques that science has to offer, provide countless possibilities to improve our understanding and treatment of the human body 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 antiquated animal experiments is better for both humans and animals.

We advocate for the immediate replacement of animal experiments with available non-animal methods and funding to develop new methods. A concerted effort to shift funding and technological development toward more non-animal alternatives will lead us toward a future where animal experiments will become 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. The 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 what might happen in the whole body.
  • 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 then test how they might respond to new drugs.

Back to top

What are the disadvantages to using animals in experiments?

  • 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.

Back to top

What are you doing to end experiments on animals?

We advocate for replacing animals with non-animal alternative methods when they are available and funding 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 February 2022, eight states (California, Hawaii, Illinois, Maine, Maryland, Nevada, New Jersey and Virginia) have passed laws banning the sale of animal-tested cosmetics.
  • Internationally, 41 countries have passed laws to limit or ban cosmetics animal testing, including every country in the European Union, Australia, Colombia, Guatemala, Iceland, India, Israel, Mexico, New Zealand, Norway, South Korea, Switzerland, Taiwan, Turkey, the United Kingdom and several states in Brazil.
  • 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 U.S. We are committed to ending this practice.

  • 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 to be adopted.

  • In 2021, we released a report examining the government’s role in using dogs in experiments. We found that the U.S. government spends millions of taxpayer dollars to fund harmful experiments on dogs each year—and also requires or compels companies to 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.

  • We are calling on federal agencies to develop a plan and create a timetable for phasing out and ending all experiments on dogs. We also want all the federal funding mechanisms to commit to supporting the development and use of non-animal methods.

    • 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) in risk assessment, 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 reliance on the use of mammals for testing of pesticides and chemicals by 2035.
    • We are asking the Food and Drug Administration (FDA) to support the development of methods that replace the use of dogs. 
    • We want the Department of Veterans Affairs (VA) to adopt the recommendations of independent panel review released in 2020 that analyzed their 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.
  • We are pushing states to pass laws that limit the use of dogs in testing that is not required by law, as well as laws requiring that dogs in laboratories are adopted into homes after an experiment has ended wherever possible.

Back to top

What can I do to help end experiments on animals?

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, rabbitsmice and rats.

Demand better for animals used in experiments:

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

Back to top