One pox virus is known to infect cats. It has been reported occasionally in the United Kingdom (Great Britain) and Western Europe, but not in the United States. The virus is indistinguishable from cowpox virus. Cats are believed to contract this virus while hunting. Most infected cats are from rural environments and are known to hunt rodents, which are believed to be the reservoir host. Infection in cats is seasonal with most cases occurring between September and November. Cats can also contract the virus from other cats, but signs are unlikely to be seen in these cases.
Most cats with pox virus infections have a history of a single affected area, usually on the head, neck, or forelimb. The primary abnormality can vary from a small scabbed wound to a large abscess. Widespread secondary areas start appearing about 7 to 10 days after the primary one. These develop into well-defined, circular ulcers about 0.2 to 0.4 inches (0.5 to 1 centimeters) in diameter. The sores become covered with scabs. Healing is complete in about 6 weeks. Many cats show no signs other than the affected areas of skin, but about 25% develop mild nose or eye infections. Some cats may also have a fever and a decreased appetite and energy level early on in the disease process. In rare cases, cats may develop a severe generalized form of the disease that affects the liver, lungs, trachea, bronchial tissues, the mouth lining, and the small intestine. This form of the disease, which is often fatal, usually occurs in cats with a suppressed immune system, such as those with feline leukemia virus or feline immunodeficiency virus.
Laboratory tests can confirm a diagnosis of pox infection. Veterinarians will usually suspect a pox infection if the cat is from an area where the disease is known and the cat has a habit of hunting.
Prompt diagnosis is important because steroid treatment (which is often used for other skin conditions) is not appropriate for pox infections. The virus can also cause localized skin disease in people, so appropriate precautions to minimize contact with infected cats should be taken. For pet cats, supportive treatment—usually including broad-spectrum antibiotics and fluid treatment—is generally successful, and most cats recover from the infection.
Also see professional content regarding pox diseases.