Feline Immunodeficiency Virus (FIV)

The following information was written by Alice M. Wolf and Bruce Lawhorn* and put out by The Texas A&M University System.

Feline immunodeficiency virus (FIV) causes chronic disease in cats (aquired immunodeficiency syndrome, or AIDS) similar to the disease caused by human immunodeficiency virus (HIV) in human beings. Although the two viruses belong to the same family, the feline virus is not transmissible to human beings and the human virus is not transmissible to cats.

FIV infection has been found in cats worldwide. The disease occurs more commonly in male cats than in females; the highest incidence is in cats older than five years of age. Free-roaming cats and mixed breed cats are at highest risk for contracting FIV infection. The disease is rare in cats housed strictly indoors or in catteries.

FIV is transmitted from cat to cat very efficiently by cat bite wounds and blood transfusions. Infection by casual contact (e.g., using common food bowls or litter pans) does not occur. To date, it does not appear that an infected female can pass the virus to her kittens before they are born or through her milk. Again, FIV is very specifically adapted to infect cats; human beings are not at risk from this disease.

Several weekss following infection with FIV the cat will have a short, mild illness with fever and lymph node enlargement. Often the signs of illness during this stage are so subtle that the owner will not notice that the cat is sick. These early signs will disappear without treatment after a few days or weeks. The virus then undergoes a period of dormancy. Although FIV is still present in the cat, the animal will be apparently healthy and show no signs of illness for months or years.

Eventually the virus will become reactivated and upset the balance of the cat's immune system. At this time the cat will begin to show signs of chronic infections of the mouth (gingivitis), nasal cavity (rhinitis ans sinusiti) or skin. Chronic intractable diaarrhea occurs in some cats; tumors appear in others. Neurologic signs such as behavioral changes, dementia, aggression, inappropriate elimination behavior and seizures have been seen in some FIV-infected cats.

The diagnosis of FIV infection is confirmed by finding antibodies to the FIV virus in the cat's blood. This test can be done by your veterinarian. Any sick cat should be tested because of the association of FIV with chronic illness in the cat. Because apparently healthy cats may harbor FIV in a dormant state for many years, it is wise to also test new adult cats coming into a household and cats entering closed populations, especially catteries.

There is no specific treatment for FIV infection. Drugs currently used against HIV infection (e.g., AZT) are toxic to cats. Veterinarians treat the symptoms, such as infection or cancer, and give supportive care. Unfortunately, the outlook for cats in the advanced stage of this disease is poor. Even if the signs of illness can be temporarily controlled, FIV infection is ultimately fatal to the cat.

At this time there is no vaccine for preventing FIV infection. You can reduce the risk by neutering your cat to reduce roaming and territorial fighting behavior, and by keeping your cat indoors.

* Associate professor of small animal medicine and surgery and Extension veterinarian, The Texas A&M University System.

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