Feline immunodeficiency virus (FIV) is a lentivirus that affects domesticated housecats worldwide. FIV is in the same retrovirus family as Feline leukemia virus (FeLV).

The primary mode of transmission for FIV is deep bite wounds whereas FeLV is easily spread by casual contact such as grooming and shared water bowls; experts disagree as to whether FIV can be spread by casual contact. FIV attacks the immune system of cats, much like the human immunodeficiency virus (HIV) attacks the immune system of human beings. FIV and HIV are both lentiviruses, however, neither can infect the other's usual host: humans cannot be infected by FIV nor can cats be infected by HIV. Because biting is the most efficient means of viral transmission, free-roaming, aggressive male cats are the most frequently infected, while cats housed exclusively indoors are much less likely to be infected.

FIV infected cats are often unnecessarily euthanised. A vigilant pet owner that treats any secondary infections can make the difference. An infected cat can often live a nearly normal life span. The chance that an FIV infected cat will pass the disease onto other cats within a household is less than 2% as long as there is no fighting or biting. Keeping infected cats separated from disease free cats is the only sure way of preventing the spread of the disease.

FIV can infect other feline species, and in fact in some large wild cat species, such as African lions, the virus is commonly present. However, unlike in domestic cats, the virus does not necessarily cause disease in these species, perhaps because these species have acquired, during evolution, mutations that confer resistance to it.

External links

• Information on FIV from the Cornell Feline Heath Center
• FIV in African Lions, from The Lion Research Center
• Owning an FIV+ Cat from the Mar Vista Animal Medical Center
• Information on FIV from the CatChat.org The Cat Rescue Resource
• Information on FIV from the Catwork Sanctuary For Cats in Somerset England