Feline immunodeficiency virus

Feline immunodeficiency virus, or FIV, is a retrovirus related to the human immunodeficiency virus, though it infects only cats and cannot spread to people. It passes mainly through deep bite wounds, so it is most common in unneutered, free-roaming males that fight. Casual contact such as sharing a bowl or grooming carries a much lower risk, and a mother can rarely pass it to kittens.

After infection a cat can stay healthy for years. When the immune system weakens, signs may include recurring infections, gum and mouth disease such as stomatitis, weight loss, poor coat and swollen lymph nodes. Many FIV-positive cats live a normal span with regular checkups and prompt treatment of infections.

The usual test looks for antibodies in a blood sample. Kittens under about six months can test positive because of antibodies from their mother, so vets retest them later. A positive adult is usually confirmed with a second test. A vaccine was sold in the past in some countries, and it can make test results hard to read, so tell your vet if your cat was ever vaccinated. Ask your vet whether an FIV-positive cat can safely share a home with other cats, and whether it should live indoors.