The clinical course of disease in cats closely approximates HIV infection in people. The end result of immunosuppression is that other infectious diseases are allowed access to the body, and death is usually the result of the other infections. In veterinary medicine, death is often from euthanasia. The disease has been described in stages, similar to those used for HIV infections in people. There is an initial infection which may show diarrhea, fever and a depressed state.
Death is rare in the initial stage.
A carrier state is next. Cats may carry the virus without overt signs of disease for months or years. Other stages that follow have to do with signs of illness. Chronic bacterial or parasitic infections are sometimes seen. Cancers, neurologic, ocular, kidney, immunologic, fungal, viral, and protozoan infections can all be found in later and end-stage FIV infections.