Feline immunodeficiency virus (FIV) is a “slow virus” in the same category as the feline leukemia virus, though FIV differs in fundamental ways from feline leukemia in terms of the shape of the virus itself and how it causes disease. In the U.S., about 1.5-3% of healthy cats are infected with FIV.
FIV is spread primarily through biting. Consequently, aggressive free-roaming male cats are the most commonly infected. However, cats in households were they are either the only cat or do not fight with other cats in the house are at very low risk of infection. Rarely, the infection can be passed from a mother to her kittens when they pass through the birth canal or via infected breast milk.
Eventually, a cat infected with FIV suffers from a state of immunodeficiency, in which normal bacteria, viruses, fungi, etc. that would be inconsequential to a normal cat can cause severe illness in an FIV-infected cat. However, a cat with FIV can remain seemingly healthy for many years before any symptoms present themselves.
Symptoms of FIV may include:
- poor coat condition
- persistent fever
- gingivitis (inflammation of the gums)
- loss of appetite
- slow, but persistent and progressive, weight loss
- more common occurrence of cancers and blood diseases
- abortion of kittens (in unsprayed females)
- seizures, behavioral changes, and other neurological conditions have been reported
For more information about FIV, including how it is diagnosed and management, please see the link cited below. Talk to your veterinarian about any concerns you may have.