AIDS in cats is caused by the feline immunodeficiency virus, FIV, which like HIV in people, causes a permanent infection that eventually leads to a diminished function of the immune system and various associated clinical disease.

The virus can affect any cat. It is spread by close contact, especially bite wounds. It can also be spread from mothers to unborn kittens transplacentally. The virus is shed in most body fluids. The virus does not survive well in the environment, and is destroyed by sunlight, drying or disinfectants.

Many cats do not show any sign of infection initially. This can last for years. Eventually, the virus weakens the immune system. When that occurs, secondary infections occur, which can be deadly. Signs that occur in later disease include intermittent fevers, lethargy and infections in the mouth. Neurological signs and inflammation of the eyes are also common.

Because cats can be asymptomatic shedders of the virus and transmit the infection to other cats, it is always recommended that cats be tested for FIV at some point in their lives. Most cats are tested when they are acquired as a new pet. Diagnosis of FIV infection is commonly made from a blood test that is available in most veterinary clinics. In positive cats, further tests are required to see what organ systems have been affected by the FIV infection.

No treatment has been proven to eliminate FIV infections. Some antiviral drugs have been tried, but no treatment is curative. Healthy FIV-positive cats do not require any specific therapy. Sick cats that are FIV positive are treated with appropriate medications and supportive care.

Cats with FIV infection should be kept indoors and isolated from noninfected cats. Infected cats should not be bred, because the virus may be transmitted to the unborn kittens. FIV-positive cats do not benefit from vaccination for FIV. However, they should receive vaccinations for other feline diseases as long as they remain healthy. Vaccination for FIV is not currently recommended for all cats, because it does not provide 100 percent protection.

Cats with FIV infection may have a normal healthy life. In the later stages of FIV disease, when the cat is severely immune-compromised and has secondary conditions, prognosis is poor. But euthanasia is never recommended based on a positive FIV test alone.


Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.

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