Owners surrender millions of cats to animal shelters each year for euthanasia. Inappropriate elimination, most commonly associated with urologic signs, was the must common reason given for abandoning the cat. Oral disease recently was reported to be the most common health problem of cats, with a prevalence ranging from 23 to 67% of cats examined. Obesity is also 3 common problem of cats; the prevalence ranges from 1.8 to 40% and appears to be increasing. Hyperthyroidism, first reported in 1979, also appears to be diagnosed with increasing frequency. The causes of these problems have not yet been clearly elucidated and may be Influenced by both internal and external factors. Internal factors include the cats genetic and experiential background as well as its temperament. External factors include such variables as the complexity of the environment, resource quality and availability, and presence of sources of threat and conflict. Of course, these factors are not mutually exclusive and vary over a continuum that includes elements of each.