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Animals Used in Research: Overview

Facts and Figures

Worldwide, an estimated 192.1 million animals are used every year for scientific purposes. Some animals used in science are protected by the Animal Welfare Act (AWA), which means their use must meet certain (minimal) welfare standards and their numbers are tracked, such as where they are used, how many are used, and what they are used for. Animals including dogs, cats, and primates, for example, are covered by the AWA. 

However, the overwhelming majority of animals used in science — somewhere between 95 and 99% — are not protected. Of these unprotected animals, nearly all are mice or rats. Because these animals are not regulated, we do not have solid data for mice and rats, not even the number used. Nonetheless, by extrapolation, one scientist estimated that around 111.5 million rats and mice are used annually in medical research in the United States. In terms of animals that are covered by the AWA, Massachusetts leads the country at nearly 85,000 animals.

With regard to animal used in testing specifically (as opposed to animals used in research), the top 10 countries in the world are estimated to be China (20.5 million), the United States (15.6 million), Japan (15.0 million), Canada (3.6 million), Australia (3.2 million), South Korea (3.1 million), the United Kingdom (2.6 million), Brazil (2.2 million), Germany (2.0 million) and France (1.9 million). The U.S. is the second highest country in number of dogs used for testing (preceded by China).

The History of Using Animals in Research

Vivisection—the act of cutting into a living animal, usually for the purpose of physiological and pathological knowledge—has been practiced since ancient Greek and Roman days, when live animals were cut open without anesthesia to study bodily functions. Similar practices continued throughout much of the Middle Ages. In the second half of the 1600s, however, following a dramatic rise in animal experimentation during the Renaissance, some philosophers began to object to the suffering inflicted on animals used for scientific purposes. Throughout the 1700s and early 1800s, these concerns continued to gain steam. In 1863, British women led the first organized protest against vivisection in Florence, Italy. The first Cruelty to Animals Act, which mandated the use of anesthetics during vivisection, was passed three years later in 1876 England.

Concurrently, however, in the mid-nineteenth century, the 1859 publication of Charles Darwin’s book On the Origin of Species furthered the idea that animals could serve as models for humans in the study of biology and physiology. Additionally, Claude Bernard’s 1865 An Introduction to the Study of Experimental Medicine popularized the idea of vivisection as the foremost methodology for scientific research. During this period and through World War I, animal research was established as the predominant method of laboratory investigation. After World War II came an additional surge in the use of animals in research as the federal government began providing a significant amount of scientific research funding.

In 1966, Congress passed the first legislation aimed at regulating the care and use of animals in U.S. laboratories. Called the Laboratory Animal Welfare Act, it was enacted following a rise in public concern over the mistreatment of lost and stolen cats and dogs by laboratory animal dealers. Later strengthened through three major revisions and renamed the Animal Welfare Act, it now covers animals not only in laboratories but also in zoos, circuses, and aquaria, in addition to overseeing animal transportation and animal fighting.

A critical deficiency of the AWA, however, is its exclusion of rats, mice, and birds, which account for roughly 95% of all animals used in research worldwide. Thus much suffering goes unregulated and uncounted. While a number of legal challenges have been made to include rats and mice under the AWA, to date these efforts had been moderately successful, gaining support in the court system but obstructed legislatively or due to the USDA failing to fulfill its obligations.

Animal research reached its highest level in the United States in the mid-1980s following decades of public support for scientific research of all kinds. During this same time, however, animal protection advocates successfully pressured numerous cosmetics companies to reduce or eliminate animal use in the testing of their products by replacing them with non-animal testing methods. In the 1990s, the number of animals used in research briefly declined—some say by as much as 40-50%, but it is difficult to say with certainty. To date, however, the number has again increased as a result of the use and maintenance of genetically engineered animals (who have had their genetic code altered to produce a specific result), especially rats and mice.

The Purpose of Using Animals in Research
Animals are used in laboratories today for one of three main purposes: (1) biomedical research (e.g., exploring disease mechanisms, testing vaccine efficacy and protection); (2) testing consumer products (e.g., assessing the safety levels of products such as cosmetics and household paint); and (3) education (e.g., surgical training in medical and veterinary school).

1. Biomedical Research. A 2021 study estimates that more than 111 million mice and rats are used annually in U.S. biomedical research, a figure that represents more than 99% of all lab animals.

Biomedical research is based on the idea that animals are similar enough to humans to serve as “models” for the study of human organ systems. Discoveries credited by scientists to the use of animals in research include penicillin, insulin, the polio vaccine, chemotherapy for childhood leukemia, and heart bypass surgery.

However, critics of biomedical animal research—a group that includes many scientists—challenge the assumption that animals are appropriate models for humans.

Before new compounds can even be tested on small groups of humans, they are first tested extensively on animals, an inefficient process given that upwards of 95% of drugs shown to be safe and effective in animals fail in human trials. Critics of animal research also point to instances of animal research that falsely concluded that a drug or vaccine was safe when in fact it turned out to be harmful to humans. In the last two decades, many drugs, including Eferol, Oraflex, Suprol, and Selacryn, have been taken off the market after causing hundreds of deaths and/or injuries, despite having passed safety tests in animals.

Those who question the use of animals in research also raise concerns about the possibility of rejecting compounds that could be highly beneficial to people even though they are toxic to certain animals. If penicillin, for instance, had been tested only in guinea pigs, humans might never have benefited from this life-saving antibiotic.

2. Consumer Product Safety Testing. U.S. government agencies require an extensive array of animal tests to assure the safety of items such as shampoo, food packaging, and household cleaners. These products are tested for their toxicity to the eyes and skin, for their potential to cause internal organ damage, and for their safety for use by pregnant women. In some cases, animal tests are specifically required by a federal regulatory agency. In other cases, only the “best available” safety information is requested. Many American regulatory agencies, however, still believe that traditional animal tests are the “best available.”

While there is still much progress to be made, many manufacturers have dramatically reduced their reliance on animal use in product safety testing in the last two decades. Two crucial components of this change have been the sharing of information about the safety of ingredients and product formulations, as well as the utilization of computers in facilitating searches of databases containing this information. While truly reliable figures are not available, it is estimated that of all of the animals used to test the safety of personal care products in the U.S., only 5% are protected through the AWA.

3. Animals in Education. Medical schools historically used animal labs for education, but they have made great progress in recent years with all medical schools in the U.S. having now ceased the use of animal laboratories. Some veterinary schools still use live animal labs in their educational programs and many of the dogs used are anesthetized healthy dogs that are used for terminal surgical training. Most veterinary schools, however, have phased out of terminal surgical training and are instead providing their students with surgical experience on organ models, in spay/neuter clinics, or via Educational Memorial Programs (EMPs) wherein pet owners can donate the bodies of their deceased animals to veterinary schools for surgical and anatomical training. Further, new technology is being developed. For example, a biotech company called SynDaver released a synthetic canine model that mimics the functions of a living dog. It is anticipated that this synthetic model will revolutionize veterinary surgical training.

In addition to laboratory animals used in higher education, millions of additional animals are killed each year for use in dissection classes in elementary and secondary schools. Frogs are most common, but cats, fetal pigs, rats, and snakes are also used, despite the availability of a wide variety of alternatives that have been demonstrated to provide students with equivalent learning experiences. These alternatives include interactive programs, virtual reality programs, as well as non-living animal models, which can be used instead of live animals to study anatomy. To date, 21 states as well as Washington, D.C. protect a student’s right to choose humane alternatives to dissection without being penalized. (These protections are afforded through state law, resolution, or Board of Education policy.)

Sources of Lab Animals

There are three primary sources of laboratory animals: wild, purpose-bred, and stray or unwanted animals. Most are purpose-bred—that is, they are bred in a laboratory specifically for use in research, testing, or education. The federal government identifies those who breed and sell these animals as Class A animal dealers, and they are licensed and regulated by the USDA.

Random source dealers, or Class B dealers, are also licensed and regulated by the USDA. These dealers are those licensed to collect laboratory animals from “random sources:” pounds, auctions, or individuals like private breeders and hunters. While “pound seizure,” the practice of acquiring laboratory animals from pounds and shelters, is prohibited by law in some states (Massachusetts was the first state to make this practice illegal in 1986), other states allow for animals in pounds to be turned over to research facilities. 

In 2009, the NIH published a detailed report on the use of random source dogs and cats, in response to repeated concerns voiced by the public about Class B dealers. Among other findings, the NIH concluded that there were not “any unique or irreplaceable features that made it necessary to obtain random source animals from Class B dealers.” In 2012, NIH stopped funding research studies using cats from random sources and did the same for dogs in October 2014.

Although there are now only a handful of Class B dealers left in the United States—down from hundreds in the 1970s—they remain a serious concern. Kenneth Schroeder, for example, a Class B dealer, had his license revoked when he was accused of having “willfully violated the Animal Welfare Act” by obtaining seven dogs illegally, failing to provide proper housing, and refusing to allow USDA inspectors access to his records and facilities. An HBO documentary Dealing Dogs reveals the horrifying conditions of C.C. Baird’s facility Marin Creek Kennels. His license has since been revoked and he has been fined.

Laboratory Animal Care and Use

The Animal Welfare Act (AWA) is the most significant law governing the care and use of laboratory animals in the United States. Passed in 1966, the AWA has since been amended eight times and covers all warm-blooded animals, except for mice, rats, and birds. The AWA’s regulations spell out requirements for veterinary care, adequate food and water, protection from temperature extremes, shelter from outdoor elements, sanitation, and record keeping.

A separate piece of legislation, called the Health Research Extension Act, passed in 1985, covers all vertebrates — including mice, rats, and birds — used in research, testing, and education that is funded by the Public Health Service (PHS). The PHS Guide for the Care and Use of Laboratory Animals sets the standards for care and housing that must be provided to animals in PHS-funded studies.

Almost all animals in laboratories suffer to one degree or another from the stress of confinement, but they do not all experience pain or even distress as a result of experimental procedures. In 2019 (the most recent year that data is available), the USDA reported that nation-wide, of warm-blooded animals in laboratories covered by the AWA, 15% were held in laboratories but not used in research; 56% were used in research and experienced no pain and did not receive pain drugs; 24% were used in research and experienced pain and received pain drugs; and the remaining 5% were used in research and experienced pain and did not receive pain drugs. The total number of AWA-covered animals either kept for research or used in research in 2019 in the United States was 934,771. The total figure is likely drastically higher, as around 95% of animals used in research are not covered by the AWA, and therefore are not accounted for.

In 2019, the USDA reported that 92,130 AWA-covered animals were held and used in research facilities (latest year that data is available). Of those, 8% were held in laboratories but not used in research; 72% were used in research and experienced no pain and did not receive pain drugs; 19% were used in research and experienced pain and received pain drugs; and the remaining 1.2% were used in research and experienced pain and did not receive pain drugs. Again, these figures include only the roughly 5% of animals for whom there are reporting requirements. If all animals were accounted for, the likely number of vertebrates used in Massachusetts for research in 2019 would be around 1.5 million.

While some laboratory animals die as a result of experimental procedures, most are euthanized for postmortem examination or when they are no longer needed. Many animals are simply kept in laboratories until they are needed, where conditions can be just as poor as for animals actively being used. In a notorious example, in 2022, the government seized over 4,000 beagles from Envigo, a Virginia facility that breeds dogs for research, and after further investigation shut down the company entirely.

According to the AWA, facilities using animals for research, testing, or education must form an Institutional Animal Care and Use Committee (IACUC) to oversee their animal programs. IACUCs are composed of scientists, veterinarians, and at least one member of the general public who is not affiliated with the institution in any way. IACUCs not only inspect the institution’s laboratories, they must also review and approve all research protocols before any animals can be used. They also look for evidence that the investigator has made a concerted effort to find alternatives to research that might cause pain and distress, and if animals must be used, that there is a plan for alleviating that pain and distress. The amount of time and effort put into these efforts, however, varies widely.

Alternatives to Animals in Research

While laboratory animals are the primary vehicle for research in the United States, an increasing number of alternatives to animal research now offer new hope for the welfare of millions of these animals used in biomedical research, product safety testing, and education. While the use of alternatives doesn’t always mean eliminating animals altogether, the number of animals being used has been dramatically reduced in recent years, and the lives of many others have been significantly improved. The words now used almost universally by the research community and by animal protection advocates to describe alternatives are the Three Rs – Replacement, Reduction, and Refinement.

The widely-applied concept of the Three Rs was originally introduced in the 1950s by William Russell and Rex Burch, British biologists who sought to lessen the suffering of laboratory animals. Replacement means substituting other systems for whole animal use. Reduction means decreasing the number of animals to the minimum needed to yield accurate data. Refinement means using modern medicine to minimize or eliminate pain and distress and employing housing and husbandry techniques to enrich the captive environment to reduce boredom and promote natural behavior. Please see our webpage on Laboratory Animal Alternatives – The Three Rs for more information.

What Can You Do?
Know that you are not alone. While the sheer scope of the issues impacting laboratory animals may seem daunting, individuals can make a positive impact on the welfare of laboratory animals in several ways:

  • Be in the know. Public pressure has been the primary force behind all the improvements that have been made over the years in the laws and regulations protecting animals in laboratories. Join groups that promote laboratory animal welfare, such as the MSPCA, Rise for Animals, the Physicians Committee for Responsible Medicine, and the American Anti-Vivisection Society. These organizations send e-newsletters and alerts to educate members about lab animal issues and let them know when their voice can help laboratory and other animals.
  • Be an educated and conscientious consumer. Consider purchasing products made by companies that are doing the most to develop and promote alternatives to animals in testing their products’ safety. When making investments, consider those companies that don’t test on animals, don’t support animal-based research, or have committed to minimizing the number of animals used to test their products.
  • Please see our information on Cruelty-Free Labeling and Product Safety Testing on our website.
  • Be an educated learner. If you or members of your family are an educator or student of any level, educate yourself, your family, and your institution about alternatives to the harmful or invasive use of animals in the classroom.
  • Learn more about pending legislation that could impact animals used in research on our state legislation page and our federal legislation page.

Join the Animal Action Team to stay up to date on animal issues across the Commonwealth.

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