Animal Testing

Biomedical Research

Animals are used to understand basic biology, as “models” for studying human biology and disease, and as test subjects for the development and testing of drugs, vaccines, and other biologicals (i.e. antibodies, hormones, ingredients in vaccines, etc.) to improve and advance human health. As models, scientists aim to produce artificially, a condition in an animal in a laboratory that may resemble the human equivalent of a medical disease or injury. Animals are used in all capacities of research: for example, a rabbit’s sensory system may be studied in basic research; she may be used as a model for eye and skin disorders, or used in eye and skin irritancy tests for environmental toxicity testing.

The exact number of animals used in biomedical research is unknown, particularly since government statistics do not include mice, rats, birds, and fish; some estimates place the total number of these species in research to be in the tens to hundreds of millions. The use of genetic engineering—manipulation of an animal’s DNA or genes—is prevalent throughout many fields of research, particularly biomedical. “…[T]he mouse has become the flagship of animal testing, especially useful with genetic modifications, gene knockouts [genes are removed], and knockins [genes are added]. In 2003, NIH [National Institutes of Health] launched the Knockout Mouse Project and has awarded more than $50 million with the goal of creating a library of mouse embryonic stem cells lines, each with a gene knocked out.”1

While most animals are purposely bred for research, others, like cats and dogs, may be acquired through different sources, such as auctions, advertisements, or from pounds and shelters (known as “pound seizure”). Of the many species used in biomedical research, specific animals are preferred in certain areas. Dogs, typically young purpose-bred beagles, are commonly used in cardiovascular studies, heart and lung research, genetic studies, age-related research, pulmonary studies, cancer research, and orthopedics, such as the development of prosthetic devices for hip and knee replacements, vertebral fusion models, cervical disc degeneration, etc. Cats “have long been a mainstay of NIH-funded studies of neurological, cardiovascular, and respiratory diseases, and the IMMUNE SYSTEM.”2Researchers also use cats in cancer research, genetic disorders, and eye, ear, and infectious disease research. Nonhuman primates are used in research on vaccines, infectious, cardiovascular, and neurological diseases, aging, reproductive biology, gene therapy, drug addiction, xenotransplantation (cross-species transplants), and vaccine and toxicity testing. The two most common primate species used by far are Rhesus and Cynomolgus macaques—also known as crab-eating macaques. Of the nonhuman great apes, chimpanzees are currently the only species used in biomedical research.

Researchers frequently use rabbits in toxicity and safety testing of medical devices, vaccines, and drugs. In 2009, over 222,000 rabbits were used in research, more than any other species covered under the Animal Welfare Act (AWA), followed next by guinea pigs and hamsters, who are both used a great deal in toxicity testing and as models for infectious, cardiovascular, and neurological diseases, and drug abuse research. Both mice and rats are heavily used in vaccine and drug research and testing, and birds are used in research on organ development and deformity, visual impairment, muscular dystrophy, and nutrition, among other things.

Basic research

Basic research is exploratory research, an open-ended search for more information for knowledge’s sake. “Basic biological research has traditionally studied life at the most basic level; what the cell is, what it is made of…what everything is built of and so forth.”[3] A wide variety of animals are used in basic research, with mice being the most common. Rats, birds, amphibians, and fish are also used, and invertebrates such as fruit flies and worms are heavily used in genetic research. “Historically, animal use in research was synonymous with basic research. It was easy to dissect or vivisect animals without any particular end in mind.”[4] In many ways, this is still true today. Stated in a 2010 review on the use of animals in basic research, “According to figures from the NIH, basic biomedical research receives more FUNDING than all other forms of research, [and] uses animals more often than not…”[5]

While basic research does not set out to find cures for human diseases, “much current [basic] research [is] being done under the guise of applied research because it increases the likelihood that the project will be FUNDED by a granting institution.”6 In a 2009 review of animal models in research, the authors list several NIH-funded research grants that are basic research, but described under the pretense of applied research by claiming clinical relevance for humans.7 By claiming potential clinical applications, a slippery slope is created that allows any and all animal research to be justified in spite of contrary evidence to its applications for humans. As stated in a 2011 science news article, “With an annual budget for NIH of more than $30 billion, the problem is not the amount invested in MEDICAL RESEARCH, but how it is used. Right now we’re operating under the assumption that somehow there’s a yet-to-be-discovered silver bullet, and that if we just spend more money on fundamental science, researchers will discover that silver bullet and all will be well. It’s not going to work that way.”8

Animal models

For practically every known human disease, researchers attempt to induce similar aspects of the disease in animals to create an animal “model” of that disease. Supposedly predictive, animals “are used with the aim of discovering and quantifying the impact of a treatment, whether this is to cure a disease or to assess the toxicity of a chemical compound.” This is how animals are “used in the context of DRUG TESTING and studying human disease.”9Areas of disease research involving animals include neurological, infectious, digestive, genetic, connective tissue, and chronic diseases. In these areas, animals are used as models of traumatic brain injuries, spinal cord injuries, congenital blindness, Parkinson’s, Alzheimer’s, AIDS, DIABETES, cancer, obesity, and so on.

In order to create these models, animals are subjected to invasive procedures, which can include surgeries, traumatic injuries, burns, force-feeding, blood draws, biopsies, food, water, and social deprivation, dart gun sedation, prolonged restraint, behavioral and environmental manipulations, viral and bacterial infections, and exposure to toxic drugs and chemicals. Examples include, “creating heart attacks, heart failure, abnormal heart rhythms, strokes, and other cardiovascular traumas in monkeys, dogs, pigs, and other animals; inducing symptoms of MIGRAINES in cats and primates through brain stimulation and manipulation with chemicals; implanting electrodes into the intestines of dogs to induce motion sickness and vomiting; implanting electrodes into the brains and eyes of monkeys and cats to conduct neurological and vision experiments; and dropping weights onto rodents to produce spinal cord injuries and paralysis.”10

Drug and vaccine development

Millions of animals and taxpayer DOLLARS are used in the production and testing of biologicals, such as vaccines and antibodies. For example, a complete batch test for a therapeutic protein can involve 12,000 mice and cost $2.4 million; 2007 estimates for the cost of drug development and to bring it to market range from $800 million to $1.7 billion. Potential drugs are often required to be tested in at least two animal species in preclinical trials before moving on to human CLINICAL TRIALS.11 Yet “only around 5% of drugs that show potential in animal studies ever get licensed for human use.”12 Potency tests of such products as vaccines are still based routinely on the principle of protection, i.e., survival or death after exposure, which was first introduced in the 1890s. Many of these tests are exceptionally cruel, involving high levels of pain and distress for a range of species from rodents to nonhuman primates (including chimpanzees). According to 1998 USDA statistics, more than 60 percent of the animals reported to experience unrelieved pain were used for vaccine testing.


Animals have proven to be poor models for human disease research. Because they are genetically different from humans, studying diseases in animals can give us inadequate or erroneous information. “The difficulties associated with using animal models for human disease result from the metabolic, anatomic, and cellular differences between humans and other creatures…”13  According to Dr. Richard Klausner, former Director of the NATIONAL CANCER INSTITUTE, “We have cured cancer in mice for decades—and it simply didn’t work in humans.”14 Even with genetic engineering, animals are still proving to be poor models for humans. For example, despite the $50 million awarded by NIH for the Knockout Mouse Project, the genetically manipulated mice have their problems; for instance, “The current knockout mouse model for amyotrophic lateral sclerosis (ALS) may be completely wrong…”15

While the U.S. spends more money on animal research and health care than any other nation, we “… [fall] to the back of the pack when it comes to health indicators such as life expectancy…”16


[1] Gawrylewski, A. (2007, July 1). The Trouble with Animal Models. The Scientist, 21(7), 44.

[2] National Research Council. (2009). Scientific and Humane Issues in the use of Random Source Dogs and Cats in Research. Washington, DC: The National Academies Press.

[3] Greek, R., & Shanks, S. (2009). Animal Models in Light of Evolution. Boca Raton, FL: BrownWalker Press.

[4] Greek, R., & Shanks, N. (2009). FAQs About the Use of Animals in Science. Lanham, MD: University Press of America.

[5] Ibid.

[6] Ibid.

[7] Greek, R., & Shanks, S. (2009). Animal Models in Light of Evolution. Boca Raton, FL: BrownWalker Press.

[8] Waters, H. (2011, March 30). Q&A: From the lab to the clinicThe Scientist.

[9] Greek, R., & Shanks, S. (2009). Animal Models in Light of Evolution. Boca Raton, FL: BrownWalker Press.

[10] Pippin, J. (2009). Humane Seal Fact Sheet on Animal Experimentation. PCRM.

[11] Brewer, T. (2007, September/October). Trials and Errors: DRUG TESTING raises ethical – and efficacy – issues. Best Friends Magazine.

[12] Waters, H. (2011, March 8). Q&A: Improving preclinical trialsThe Scientist.

[13] Gawrylewski, A. (2007, July 1). The Trouble with Animal Models. The Scientist, 21(7), 44.

[14] Cimons, M., Getlin, J., & Maugh, T., II. (1998, May 6). Cancer Drugs Face Long Road From Mice to MenLos Angeles Times, A1. 

[15] Gawrylewski, A. (2007, July 1). The Trouble with Animal Models. The Scientist, 21(7), 44.

[16] Begley, S. (2011). The Best Medicine. Scientific American, 305, 50-55.




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