Rats and Mice
Approximately 95 percent of all laboratory animals are mice and rats. Easily housed and bred, short lived (2-3 years), small, and relatively inexpensive, these rodents have become the animal model of choice for modern medical and scientific researchers. (pdf)

Non-Human Primates
Less than ¼ of one percent of all laboratory animals needed in the U.S. are non-human primates. Approximately 30 different species are studied by the research community. Many historic scientific breakthroughs, such as the discovery of the Rh factor and the development of a live polio virus vaccine were achieved through research with non-human primates. Today they are considered extremely important models in many areas of medicine because of their close relationship to humans. (pdf)

Dogs & Cats
Dogs and cats together comprise less than ½ of one percent of all laboratory animals used in the U.S. However, their contributions to the various fields of medicine have been very significant. (pdf)

Other Species
While mice and rats are key models for research, many other animal species also have contributed to dramatic advances in biology and medicine. A review of the medical literature affirms that studies with other animals, mainly rabbits and guinea pigs, also have made enormous contributions to understanding the cause, treatment, and prevention of many complex human diseases. (pdf)