Researchers minimize pain as much as they can and select the minimum number of animals that will produce a scientifically valid answer.
Minimizing pain and avoiding distress in research animals is an ethical, legal, and scientific imperative. Many experiments are painless. Others do involve procedures that can be painful, but most of the time drugs and other measures are used to relieve the animals’ discomfort. The Animal Welfare Act and the Public Health Service Policy on Humane Care and Use of Laboratory Animals require researchers to relieve animals’ pain unless doing so would interfere with the research, such as studies on pain relief itself.
Animal research proposals must first be reviewed by an institutional animal care and use committee that includes at least one veterinarian, one scientist, and a member of the public. If a procedure is likely to cause more than slight pain — like a needle stick — the proposal must include special justification for that procedure. The committee makes certain that the experiment is needed to answer the scientific question and that the researcher does everything possible to minimize pain and stress for the animals.
In addition to ethical and legal considerations, pain and distress cause changes to the body that could interfere with the research. For this reason, minimizing pain and avoiding distress also contribute to sound science.