As neuroscientists developed reliable anaesthetic methods and delicate instruments to examine the nervous system, cats were used to study a variety of neurological problems, such as epilepsy, deafness, vision problems and others. The Nobel Prize-winning work of David Hubel, for instance, made important contributions to the knowledge of vision by studying the development and function of the visual system in cats. Due to this research, it is known that human beings are not born with a fully developed visual system, and that proper development of vision requires stimulation of the visual neurons. Cats, too, have been useful models for research on aging. Their relatively long life span compared with mice and rats makes it possible to observe the slower and more subtle effects of aging.
Cats are very important subjects in cancer research.
Leukemia is perhaps the most infamous of the diseases shared by cats and people. In cats, it is caused by an AIDS-like retrovirus. A recently discovered vaccine against feline leukemia may act as a model for an AIDS vaccine. Mammary cancer is also common in the cat, and many features of feline mammary cancer resemble the human breast cancer which, among the human cancers, is the greatest killer of women. Toxoplasmosis is a disease in cats caused by a parasite which reproduces in the cat's intestine.