Experimental research with animals is usually conducted in universities, medical schools, pharmaceutical companies, defense establishments, and commercial facilities that provide animal-testing services to the industry.

[12] Research in model organisms led to further medical advances, such as the production of the diphtheria antitoxin[13][14] and the 1922 discovery of insulin[15] and its use in treating diabetes, which had previously meant death.

[17] Other 20th-century medical advances and treatments that relied on research performed in animals include organ transplant techniques,[18][19][20][21] the heart-lung machine,[22] antibiotics,[23][24] and the whooping cough vaccine.

[33] Animal experimentation continues to be required for biomedical research,[34] and is used with the aim of solving medical problems such as Alzheimer's disease,[35] AIDS,[36] multiple sclerosis,[37] spinal cord injury, many headaches,[38] and other conditions in which there is no useful in vitro model system available.

[62][63] Discoveries in the 18th and 19th centuries included Antoine Lavoisier's use of a guinea pig in a calorimeter to prove that respiration was a form of combustion, and Louis Pasteur's demonstration of the germ theory of disease in the 1880s using anthrax in sheep.

[10][11] Drosophila became one of the first, and for some time the most widely used, model organisms,[66] and Eric Kandel wrote that Morgan's discoveries "helped transform biology into an experimental science".

[77] The ability of humans to change the genetics of animals took an enormous step forward in 1974 when Rudolf Jaenisch could produce the first transgenic mammal, by integrating DNA from simians into the genome of mice.

[79][80] Other 20th-century medical advances and treatments that relied on research performed in animals include organ transplant techniques,[18][19][20][21] the heart-lung machine,[22] antibiotics,[23][24] and the whooping cough vaccine.

[33] Animal experimentation continues to be required for biomedical research,[34] and is used with the aim of solving medical problems such as Alzheimer's disease,[35] AIDS,[36][81][82] multiple sclerosis,[37] spinal cord injury, many headaches,[38] and other conditions in which there is no useful in vitro model system available.

In the case of C. elegans, the worm's body is completely transparent and the precise lineage of all the organism's cells is known,[85] while studies in the fly D. melanogaster can use an amazing array of genetic tools.

[86] These invertebrates offer some advantages over vertebrates in animal testing, including their short life cycle and the ease with which large numbers may be housed and studied.

[92] The decision to adopt such models generally involves accepting a lower degree of biological similarity with mammals for significant gains in experimental throughput.

One of the most significant advancements in medical science involves the use of dogs in developing the answers to insulin production in the body for diabetics and the role of the pancreas in this process.

[112] In a survey in 2003, it was found that 89% of singly-housed primates exhibited self-injurious or abnormal stereotypyical behaviors including pacing, rocking, hair pulling, and biting among others.

Although the Animal Welfare Act does not include purpose-bred rodents and birds, these species are equally regulated under Public Health Service policies that govern the IACUCs.

According to the report, within a three-year period, nearly half of all American laboratories with regulated species were cited for AWA violations relating to improper IACUC oversight.

[127] With only a broad number of 120 inspectors, the United States Department of Agriculture (USDA) oversees more than 12,000 facilities involved in research, exhibition, breeding, or dealing of animals.

[128] Larry Carbone, a laboratory animal veterinarian, writes that, in his experience, IACUCs take their work very seriously regardless of the species involved, though the use of non-human primates always raises what he calls a "red flag of special concern".

Fruit flies, nematode worms, mice and rats together account for the vast majority, though small numbers of other species are used, ranging from sea slugs through to armadillos.

[214] Although transplant rejection remains a problem,[214] recent clinical trials that involved implanting pig insulin-secreting cells into diabetics did reduce these people's need for insulin.

[215][216] Documents released to the news media by the animal rights organization Uncaged Campaigns showed that, between 1994 and 2000, wild baboons imported to the UK from Africa by Imutran Ltd, a subsidiary of Novartis Pharma AG, in conjunction with Cambridge University and Huntingdon Life Sciences, to be used in experiments that involved grafting pig tissues, had serious and sometimes fatal injuries.

These toxicity tests provide, in the words of a 2006 United States National Academy of Sciences report, "critical information for assessing hazard and risk potential".

Tests on pharmaceutical products involve: It is estimated that 20 million animals are used annually for educational purposes in the United States including, classroom observational exercises, dissections and live-animal surgeries.

The operator is required to amputate a cockroach's antennae, use sandpaper to wear down the shell, insert a wire into the thorax, and then glue the electrodes and circuit board onto the insect's back.

[287] Similarly, citing ethical considerations and the availability of alternative research methods, the U.S. NIH announced in 2013 that it would dramatically reduce and eventually phase out experiments on chimpanzees.

[295] In February 1997 a team at the Roslin Institute in Scotland announced the birth of Dolly the sheep, the first mammal to be cloned from an adult somatic cell.

[310] The Stop Huntingdon Animal Cruelty campaign used tactics ranging from non-violent protest to the alleged firebombing of houses owned by executives associated with HLS's clients and investors.

[318][321] A 2021 paper found, in a sample of Open Access Alzheimer Disease studies, that if the authors omit from the title that the experiment was performed in mice, the News Headline follow suit, and that also the Twitter repercussion is higher.

Claude Bernard—who is sometimes known as the "prince of vivisectors"[328] and the father of physiology, and whose wife, Marie Françoise Martin, founded the first anti-vivisection society in France in 1883[332]—famously wrote in 1865 that "the science of life is a superb and dazzlingly lighted hall which may be reached only by passing through a long and ghastly kitchen".

[348] Another non-animal research method is in silico or computer simulation and mathematical modeling which seeks to investigate and ultimately predict toxicity and drug effects on humans without using animals.