a slow viral disease of Felidae with worldwide distribution; characterized by chronic immunosuppression and development of secondary opportunist infections and cancers. Primary route of transmission is through bite wounds, but transplacental and nursing transfer are other routes of transmission. In this species, sexual contact is not considered an important transfer route. Species-specific strain; does not cause disease in humans. Other important viruses in the genus include agents of progressive pneumonia in sheep, infectious anemia in horses (EIA), and arthritis-encephalitis in goats. FIV used as a model for human AIDS (HIV) research. Clinical signs variable and often relate to secondary invaders; fever, anorexia, gingivitis, stomatitis, poor haircoat, diarrhea, anemia, lymphopenia (CD4+:CD8+ ratio used as a prognostic parameter); bladder and respiratory infections are common signs. May cause seizures, abortions, and many cats remain asymptomatic until late stage disease. Licensed vaccine available. Feline leukemia virus, another common slow virus disease of cats is also in the Retroviridae family. SYN: cat AIDS, feline AIDS.