Like HIV, feline immunodeficiency virus (FIV) is a highly contagious disease that eventually results in the development of an AIDS-like syndrome. The prevalence of FIV in North America hovers around 2.5 per cent, although the virus may be much more prevalent in other countries (up to 44 per cent in some locations). It is generally believed that there are five strains of FIV that each causes an AIDS-like syndrome in cats. In fact, FIV is the only non-primate variation of immunodeficiency viruses that are associated with AIDS. While not usually fatal in cats, the effect of FIV on the immune system of house cats has justified the development of a vaccine.
In March of 2002, researchers announced that they had discovered a vaccine for FIV which was subsequently approved by the FDA. The discovery of this vaccine was not only of great importance in the veterinary world but was also heralded as a breakthrough in the search for a vaccine for HIV. The excitement about the vaccine notwithstanding, subsequent researchers and veterinarians have questioned its efficacy. Indeed, since its introduction to the medical community, the FIV vaccine has been criticized for many reasons.
First of all, all cats treated with the FIV vaccine test positive for the virus. For many cat owners, this has sparked justifiable fears that if their cat runs away and is found by animal control, it will likely be destroyed because it is FIV-positive. In addition, the vaccine does not provide full protection against the virus. At the moment, researchers are aware of 5 subtypes of FIV but the vaccine only protects against two of those strains. Finally, the FIV vaccine has been shown to possibly cause sarcomas which are equally dangerous to FIV.
Ultimately, whether you should vaccinate your cat against FIV is a very tricky decision and one that should not be taken lightly. Speak to your veterinarian and make an informed choice regarding the health of your cat.