Animals as a medical resource
Animals have played a significant role in medical research and advancements, serving as both subjects and sources for various medical products. Historically, animals have been used in traditional medicine and have contributed to significant medical breakthroughs, such as the development of insulin and antibiotics, through research that validates their physiological similarities to humans. While the use of animals in research has led to considerable medical progress, it is not without controversy, as concerns regarding animal rights and ethical treatment have gained prominence since the late 20th century.
Opposition from various animal rights groups has raised questions about the necessity and morality of using animals for testing, prompting discussions about alternative research methods, such as tissue cultures and computer simulations. Despite this, proponents argue that animal testing remains essential due to the complexities of biological systems that cannot be accurately replicated by current alternatives. Regulatory bodies like the FDA and USDA enforce guidelines to ensure the humane treatment of animals in research settings.
Notably, recent legislative changes have opened the door for more alternative testing methods, signaling a shift in how medical research may evolve in the future. However, advocates maintain that animal research is still crucial for understanding drug efficacy and safety before human trials. The ongoing dialogue surrounding this topic reflects a balance between advancing medical knowledge and addressing ethical considerations in the treatment of animals.
Subject Terms
Animals as a medical resource
The use of animals has been a critical component of both human medical research and veterinary research. Although animal research has become a source of controversy among the public, nearly all modern medical advances have been based on some form of animal research.
Background
Animals have served purposes related to medicine for centuries. They provided medical products for apothecaries in medieval Europe and for traditional Chinese medicine. Most applications, such as the use of ground rhinoceros horn as an aphrodisiac, were based on nonscientific concepts that have been discarded by modern medicine. However, some techniques, such as the use of spiderweb to stop bleeding, functioned until more effective products became available.
In more modern times, insulin used to treat diabetes was first harvested from the pancreatic glands of cattle or pigs used in the meat industry; however, the foreign animal proteins sometimes caused allergic reactions. Today, genetically engineered bacteria can provide many hormone products that previously were extracted from animals. Animals have also provided transplant organs. Tissue rejection has been a major problem, but medications can reduce rejection dramatically.
Through genetic engineering, genes that code for pharmaceutical proteins can be incorporated into animals, and medicinal drugs can then be produced from the animal’s milk. In 2009, the US Food and Drug Administration (FDA) approved an anticoagulant drug harvested from the milk of genetically engineered goats for the treatment of hereditary antithrombin deficiency; the drug, sold under the brand name ATryn, was the first-ever medication produced from genetically engineered animals, and the first FDA-approved biological product derived from such animals. Transgenic animals have also been proposed for the production of drugs to treat cystic fibrosis, cancer, and other disorders. Other popular medications that come from animals include estrogen, such as Premarin, and various thyroid medications. Animal-derived ingredients can be both active and inactive ingredients in medications. The uses of animals for products and tissues, however, have been minor compared with the use of animals as test subjects in medical research.
Animal Medical Research
Phenomenal advances in the treatment of human diseases occurred in the century following the US Civil War. The development of the germ theory of disease by Louis Pasteur and Robert Koch, as well as the conquest of most major infectious diseases, was based on extensive animal research. Pasteur’s studies of chicken cholera formed a basis for his work, and Koch’s breakthrough work with anthrax involved studies with sheep. Most Nobel Prizes in Physiology or Medicine (first awarded in 1901) have involved some form of animal research. The first half of the twentieth century was an era of widespread public support for medical and scientific research. Animal research underlay basic studies in the development of penicillin and other major antibiotics, as well as insulin, surgical techniques, and vaccinations. Partly because people had recent memories of the severity of such major diseases as smallpox and polio, animal research engendered little protest or controversy.
Not all animals are equally useful or appropriate in medical research because some have systems that differ significantly from human physiology. The closer an animal is to humans evolutionarily, the more likely it is that it will respond to drugs and medical interventions in the same manner that humans will. Most new drugs are first screened on laboratory rats or mice; those drugs that show promise and have no toxic effects may then be tested on primates. Approximately 95 percent of medical research uses mice and other rodents, and nearly all the mice and rats used are “purpose-bred” for research. (Cats, dogs, and nonhuman primates make up less than 1 percent of animals used in research.) The protocols for FDA approval of new drugs, as well as agricultural and environmental standards, are based on substantial animal testing to ensure the safety and effectiveness of new medications.
Opposition and Controversy
Beginning in the late 1970s, opposition to animal research began to gain national attention. The books Animal Liberation (1975), by Peter Singer, and The Case for Animal Rights (1983), by Tom Regan, provided a rationale to activists who questioned humans’ use of other animals for medical research as well as for food, fur, and other uses. Organizations opposed to some or all animal use in research range from radical groups allegedly responsible for vandalism of research laboratories (the Animal Liberation Front is among the most radical groups) to milder animal protectionist organizations. Probably the best-known animal-rights group is People for the Ethical Treatment of Animals (PETA). Well-known defenders of animal research for medical science include the National Association for Biomedical Research (NABR), the Incurably Ill for Animal Research, and Putting People First.
Some anti-animal-research activists have contended that all animal research can be replaced with alternatives, such as research involving tissue culture and computer simulation. Activists also object to the use of animals taken from animal shelters and complain that current care regulations for research animals, particularly under the Animal Welfare Act, are not rigorously enforced by the US Department of Agriculture (USDA).
The scientific community has defended animal research for a number of reasons. Biological systems are much more complex than any computer model devised, so at present computer simulation has severe limitations. New drugs rarely respond in tissue culture exactly as they do in a whole living organism. Researchers point out that although animals are taken from shelters for research use, they constitute a minuscule amount of the dogs and cats that are euthanized annually. By far, most of the animals used in research and teaching are mice and rats. Research facilities are inspected by agencies such as the USDA’s Animal and Plant Health Inspection Service, which enforces Animal Welfare Act criteria. The FDA and the Environmental Protection Agency (EPA) also have laboratory practice regulations. The research community also states that approximately 95 percent of laboratory animals are never subjected to pain and that the remaining animals are provided pain-relieving drugs or anesthetics as soon as the study permits.
In 2022, the FDA began reexamining its requirement for animal testing in response to controversy and pressure. Not only were ethical reasons at play, but although animal models helped bring new medications to the marketplace, there was an increasing acknowledgment that biological differences in how animals and humans metabolize drugs may lead researchers to make mistakes in their research. The FDA’s newly formed new alternative methods (NAM) group announced a new focus on alternative technologies, such as microphysiological systems and cellular and computational methods. Later that year, the FDA Modernization Act 2.0 was signed into law, allowing pharmaceutical companies to use alternative testing methods instead of animals for nonclinical tests before clinical trials in humans commence. Such alternative methods included computer models, 3D chips, and cell-based assays. Experts stressed that the legislation would not replace animal research, which remained an integral part of determining the efficacy of new drugs.
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