Guinea pigs and hamsters are two of the most extensively used animals in research and testing. In 2012, 212,699 guinea pigs (the highest of any animal covered by the Animal Welfare Act that year) and 147,112 hamsters were held in U.S. laboratories.
Guinea pigs continue to be used in significant numbers for toxicity and safety tests, to investigate the effects of cigarette smoke, alcohol, and drugs, and to research spinal cord injury, tuberculosis, the auditory system, kidney function, osteoarthritis, nutrition, genetics, infectious diseases, and reproductive biology.
Hamsters are frequently used to study sensory systems such as taste and vision. They are also used as models for cardiopulmonary, inflammatory, and neoplastic diseases; cardiomyopathy; estrogen-induced carcinogenesis; drug and carcinogen metabolism; muscular dystrophy therapy; aging; asthma; pancreatic cancer; prion-type (mad cow) diseases; and various aspects of natural and artificial biorhythms.
Disturbingly, guinea pigs and hamsters used were nearly 85% of all animals used in studies causing pain and distress and include no pain relief.
12 percent of guinea pigs (nearly 25,000 individuals) and 20 percent of hamsters (more than 33,000 individuals) were used in experiments that involved significant pain and distress that was not alleviated by either anesthetics or analgesics.