Feline Immunodeficiency Virus

Feline Immunodeficiency Virus or FIV is closely related to the virus that causes AIDS in people but can only infect cats. FIV weakens and eventually destroys an infected cat's immune system, which makes them extremely susceptible to infections and some types of cancer. This disease is also sometimes called feline AIDS. The virus is primarily transmitted through bite wounds, so cats that go outside or live with FIV infected housemates are at the greatest risk for contracting this invariably fatal disease.




Cats with FIV may remain healthy for a long time, but eventually their immune systems can no longer protect them against the bacteria, viruses or cell damage that we all experience as part of our day-to-day lives. Clinical signs of FIV infection can vary tremendously, but oral inflammation, lethargy, inappetence, weight loss, vomiting, diarrhea, and neurological disorders are all possible. Any sick cat or new addition to a household should be tested for FIV infection. The results of screening tests can be available within minutes, but if an animal comes up positive, infection must be confirmed using another test called a Western blot.




Although FIV cannot be cured, diagnosing the disease in an otherwise healthy cat is not an immediate death sentence. Many animals can live perfectly normal lives for many years with FIV, particularly if they are kept inside and any health problems that do develop receive appropriate and prompt treatment. Anti-viral drugs are not routinely dispensed to FIV-infected cats because they often produce unacceptable side effects. An FIV vaccine is available, but its use is somewhat controversial because cats receive only partial protection against the disease and will test positive on FIV tests after vaccination.


Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008