Feline immunodeficiency virus (FIV) is a retrovirus infection that is often referred to as cat HIV or cat AIDS because it has a similar effect on felines. The virus attacks the immune system and advances through 3 phases: the acute phase, the asymptomatic (or latent) phase, and the progressive phase, leaving the cat vulnerable to secondary infections. The primary mode of transmission for FIV is through bite wounds from an infected cat. Diagnosis is by ELISA which detects disease-specific IgG antibodies that take 2-6 months to develop post-infection, and confirmation is by PCR.