Feline Immunodeficiency Virus (FIV)


FIV is one of the most common infectious diseases of cats. It is a disease that is often misunderstood and can, unfortunately, motivate owners to elect for euthanasia upon diagnosis. It is important to understand the meaning of a diagnosis, recognition of symptoms, and prognosis of the disease. Many feline companions can live healthy lives after diagnosis for some time – so it is critical to know a few facts before making a decision.


FIV is transmitted through bite wounds- commonly seen in fighting outdoor tomcats. Gentle social grooming is not a high risk activity for transmission. On rare occasions, a queen will transfer FIV to her kittens during birth, or through infected milk.


A common screening test for FIV looks for antibodies to the disease in the blood (ELISA blood test). A positive FIV screening test does not automatically mean your companion is FIV positive. For example, kittens nursed by a FIV positive queen will be FIV positive. Also, a FIV vaccinated cat will test positive for antibodies. A second test (PCR) may help differentiate between a vaccinated cat and a FIV positive cat- but the results can be difficult to interpret. If the cat is FIV positive, the disease is species specific- which means that owners can NOT get the disease from their cats, and owners can not give FIV to their companions.


After initial infection, there is a 4-6 week grace period and then a drop in the immune system. At this time, some cats can have signs such as diarrhea, fever, or anemia. These signs are often subtle and go unnoticed. The immune system will respond and keep replication at a low rate- but not eliminate the virus. This leads to a period of prolonged health for some cats.

The virus will replicate again in some infected cats after 2-5 years (years!). These cats may then go on to show signs of disease depending on the strain of virus, replication, the cat’s own immune system and the presence of other infectious agents.

The signs of FIV are not specific, but are a reflection of weakened protection against infection.   Common signs seen in FIV cats include: weight loss, recurrent fever, enlarged lymph nodes, inflammation of gums and mouth, chronic or recurrent respiratory, eye, and GI disease, or in some cats can show neurological disease

Any patient that has a compromised immune system needs to be given opportunities to reduce their exposure to disease. This means that FIV cats should live an indoor lifestyle. This will also limit their contact with other cats, reducing the potential for transmission of disease.


A FIV positive cat can be healthy for years (years!) after diagnosis. Allowing your companion an indoor lifestyle with reduced contact to infectious agents and other cats can provide them the best chance at a good quality of life. Their guarded prognosis can be balanced by a healthy environment and educated households.

Jon SiebrechtComment