The Animals Used in Medical Research
About 95% of animals used in research are mice, rats, and other rodents bred specifically for that purpose by licensed suppliers. Fish are also a popular animal model. Dogs, cats, and primates together account for less than 1% of all animals used in research. Cats and dogs together account for less than ½ of one percent (< .5%). Non-human primates account for less than ¼ of one percent (< .25%) of all laboratory animals used in the US. Chimpanzees account for about .003% of all animals used.
Companies specialize in breeding specific animal models for different types of research. Over 99% of the animals used in research today are “purpose bred," meaning they are bred specifically for research purposes by licensed vendors. The other small percent come from licensed Class B animal dealers that are regulated and inspected by the USDA. The number of Class B dealers has dwindled to about 10 or less dealers remaining in the United States. Large animals such as pigs, cattle, and sheep are supplied from licensed agricultural sources. There are laws that require research institutions to keep updated records of where all their research animals are obtained from.
Who Cares for the Animals in Research?
Laboratory animal veterinarians, husbandry specialists, and animal health technicians ensure that research animals receive the highest quality of care. These highly trained professionals work directly with the researchers to minimize discomfort and distress for the animals. Good animal care and good science go hand in hand.
Veterinary Technicians care for the animals seven days a week and including holidays. They are responsible for doing daily health check-ups, providing food and water, changing cages, and ensuring the animals are given appropriate environmental enrichment. Tubes, nesting materials, and other toys are given to the animals to allow for species appropriate behavior. In addition, primates must be provided with an environment that assures their psychological well-being, and dogs must be given appropriate exercise.
Most animal research involves simple procedures such as change in diet, giving an injection, or taking a blood sample. When more invasive procedures are needed, the animals are given the necessary anesthetics and pain relief drugs. Care is taken to protect the animals from unnecessary stress because this can distort study results.
Researchers are deeply concerned about the condition of the animals they study. Poor care results in unreliable research data. Pain and distress are thought to have a negative effect on the immune system; therefore, researchers are careful to protect the animals from undue pain and stress. It is well recognized that animals have been indispensable to medical and scientific research. We have a moral duty to provide them the best care and treatment possible.
For additional information, check out the "Kids 4 Research" page on Caring for Lab Animals for more detailed information on the environment, caging, bedding, cage sanitation, and environmental enrichment.
Why use Animals?
Even though we look very different on the outside, animals are very similar to humans in many ways. Animals develop many of the same diseases as humans, and animals are susceptible to many of the same viruses and bacteria as humans. An animal is chosen as a model if it shares similar characteristics with humans that are relevant to the research being done.
For example: Louis Pasteur was able to develop a rabies vaccine by studying dogs because dogs and people can both develop rabies, and our immune systems react the same to the rabies virus. In this case, the other differences between dogs and humans did not matter because the research being done was applicable to both species.
The short life cycle of the animals allow researchers to study the animals throughout their entire life cycle and through several generations in a short amount of time. Researchers also have control over the animal's environment (temperature, diet, light, ventilation, etc.) to make sure the animals are kept healthy and experimental variables are kept to a minimum.
In some cases, researchers will also choose to study animals to understand the differences and see how they can apply that information to human medicine. For example, the regeneration of coronary vessels in fish, or the regeneration of nerves and whole body parts in salamanders can be studied in order to someday apply these amazing abilities to treat human diseases.
Can Animals be Replaced?
Animal models are used in addition to other methods of research such as tissue and cell cultures, chemical tests, computer models, epidemiological studies, advanced statistical methods, and human clinical trials. Utilization of these methods and better analysis of test results have helped to reduce the number of animals needed for many experiments. Researchers avoid the use of animals when it is possible to do so and they continue to search for alternative methods.
Many questions about molecular, cellular, tissue and even organ functions can be investigated using test tube, cell culture, and tissue culture models. However, some questions, such as how the environment affects an organism or how the digestive system interacts with the cardiovascular system, can only be answered using animal models. While alternative methods provide great resources for researchers, they do have limitations. Alternative methods (such as computer models) cannot give vital information about the safety and efficiency of a substance in a living system. Animal research cannot be completely replaced by non-animal methods today.
The use of animals remains an essential part of biomedical research because nothing can substitute for the complex functions of the whole living animal. New drugs, vaccines, and surgical procedures must still be evaluated in animals before they can be used on human patients.
10 Facts for common animal models by Understanding Animal Research
Examples of Animal Contributions to Research:
Armadillos- Treatment for leprosy
Cats- Studies of eye and ear disorders; functional organization of the brain; functions of neurons
Chickens- Nerve system development; The first cancer causing virus- the Rous sarcoma virus- was identified in chickens.
Cows- Smallpox vaccine
Dogs- Insulin treatments for diabetics; studies on cardiovascular disease and blindness; organ transplantation techniques; pacemaker implantation; hip and other joint replacement surgery. Click here to view a dog research fact sheet.
Ferrets- Viral diseases such as influenza; respiratory diseases; visual and auditory systems
Fruitflys- Genetic analysis; studies of motor neuron diseases and other neurological disorders like schizophrenia and epilepsy; cancer research
Guinea Pigs- Asthma treatments; nutritional studies; cholesterol studies
Leeches- Studies of memory and learning at the cellular basis of simple behavior
Lobsters- Studies of motor coordination diseases such as syphilis and Parkinson's disease
Mice- Studies of cancer, aging, immunology, genetics, cystic fibrosis, and heart attacks; neurological disorders and infectious diseases such as malaria; breast cancer studies and treatments; embryo transfer techniques in humans and domesticated and endangered animals
Nematode (Roundworm) - Discovery of RNA interference; developmental studies; the workings of the nervous system; metabolism and aging studies
Nonhuman Primates- Treatments for polio; studies of HIV and AIDS, hepatitis B and C, cancer, heart disease, brain biology, and infectious diseases; rubella vaccine
Opossums- Studies of the central nervous system and immune system
Pigeons- Studies of coronary heart disease
Pigs- Development of CAT scan; studies of the healing process of skin wounds; studies of human coronary restenosis and cardiac stents
Rabbits- Corneal transplants; cardiovascular disease and drugs that lower cholesterol and help to stop the hardening of the arteries; anthrax vaccine research
Rats- Nerve damage treatments; causes of some cancers; effects of nutrition on aging; Alzheimer's disease research; studies on spinal cord injury and drug addiction; regulation of cholesterol
Sheep- Orthopedic research on diseases and injuries of bones, joints, and muscles; anthrax vaccine
Slugs- Studies of the short and long term memory
Woodchucks- Liver cancer and hepatitis B studies
Zebrafish- Embryonic vertebrate development; gene function studies to understand the genetic mechanisms that control development in humans; cancer research