A cat's normal temperature is about 38.6 oC (101,5 oF). The critical environmental temperature is about 36 oC (97 oF), at which point a cat begin to pant to cool itself. Sweat glands exist in the pads of the feet and scattered over the body, but sweating is not a temperature regualating mechanism in cats.
One leading cause of death in domestic cats is feline leukemia, a cat specific viral disease. The virus can cause fatal tumors in almost all tissues and organs of the body. It also impairs the animal's immune system, leaving it prone to other serious infections and conditions. The virus (FeLV), a retrovirus, is transmitted by contact with infected cats and excrement. A vaccine against feline leukemia is available.
Another retrovirus that causes disease in cats is feline T-lymphotropic lentivirus (FTLV). Identified in 1987, the disease also attacks the immune system; infected cats exhibit numerous infections, lose weight, and waste away.
Feline distemper is a highly contagious viral disease, also transmitted by raccoons and weasels. The virus, a parvovirus, is transmitted by even brief contact with contaminated material and death may occur as soon as eight hours after the first sign of illness appear. A vaccine is available.
Feline viral rhinotrachetis, or cat flu, is not contagious to human or other animals. An infected cat develop a fever, begins sneezing and drooling, and becomes lethargic. This is followed by a heavy discharge from the eyes and nose. Treatment consist of antibiotics, cleaning the eyes and nose, and administering fluid.
Cats are also susceptible to flea and roundworm infestations. Treatment exist on both problems. Cats that roam outside the house can bring in parasites and transfer them and the diseases they may carry to humans. A few appear serious; cases of brucellosis and, extremely rarely, of plague have been reported. Pregnant women are cautioned about handling cats and their litter boxes because of the possibility of transfering Toxoplasmosis to their fetuses. Some people exhibit a severe allergic reaction to cats, most likely, it has been suggested, to dried spittle on their fur.