FIV: Is Your Cat at Risk?

Feline immunodeficiency virus (FIV) causes acquired immunodeficiency syndrome (AIDS) in domestic cats. Although it is related to Human immunodeficiency virus (HIV), it is a distinct virus that cannot be spread to people. FIV appears to be less pathogenic than HIV. It was first identified in 1987, but has been around much longer. It has a world-wide distribution in domestic cats and many species of wild cats. Many studies have been done to determine the prevalence of the virus. A recent study has shown a prevalence of about 6% in free roaming male cats and 1.5% in free roaming female cats. Approximately 12% of sick cats test positive for the virus in the US. Our observations agree with the studies that show male, outdoor cats who have suffered a cat bite are most often infected.

The most common mode of infection is by a deep bite. The virus is found in high concentrations in the saliva. Because free roaming male cats are the ones who engage in cat fights most often, they are most frequently infected. FIV positive queens rarely infect their offspring, although antibodies to the virus may be found for several months in kittens nursing a positive queen. The virus does not survive well outside the host so there is no risk of environmental transmission.

Infection is characterized by a long latent period during which time the immune system gradually deteriorates. Eventually, the immune system deteriorates to a level that allows opportunistic infections, systemic disease and malignancies. Some of the conditions associated with FIV infection are: stomatitis, recurrent respiratory disease, diarrhea, weight loss, cancer, ocular inflammation, renal insufficiency, neurologic disease, loss of appetite, abscesses, fever, enlarged lymph nodes and pale gums.

Infection with FIV is diagnosed by testing a small blood sample for the presence of antibodies to the virus. In adult cats, antibodies mean infection because the virus is never eliminated from the cat. False positives may be found in kittens who have antibodies from their mother but not the virus. False positives occasionally occur for other reasons and a positive healthy cat should be retested.

To prevent the entry of the virus into your house, new additions should be isolated and tested prior to admission. Cats usually develop antibodies 14-60 days after exposure to the virus. Prevention involves keeping cats indoors, away from cats with unknown FIV status. Although there is no way to eliminate the virus, many cats live years with the infection. Cats with FIV should stay indoors to prevent exposure to secondary infectious diseases and to reduce risk to others. Opportunistic infections and systemic disease should be treated aggressively.

The development of a vaccine to prevent infection has been the goal of researchers for several years. An adjuvanted whole virus vaccine was released in July of 2002. Unfortunately, there are several problems with the vaccine. One problem is that vaccinated cats will test positive for the virus thus making it impossible to know which cats are infected and which were vaccinated. This becomes a major problem when these cats stray from their homes and arrive at shelters. Positive FIV cats are not generally adopted. Another problem is that the protection is limited because the vaccine does not include all sub-types of the virus. Immunity to one virus sub-type does not confer protective immunity against other sub types. For these reasons, The Cat Clinic of Stillwater does not recommend the FIV vaccine.

FIV contributes to many disease conditions. It is best prevented by testing all cats and keeping infected cats inside. With good preventive care and prompt intervention in the face of disease, FIV positive cats can live a long and comfortable life.