Feline Immunodeficiency Virus is the feline equivalent of HIV in humans. It is spread by aggressive biting behaviour and so un-neutered outdoor cats, especially males, are most at risk. It can also be spread by mating (in semen) and infected queens (female cats) can pass it on to their kittens during pregnancy and after birth through their milk.

The 1st stage of infection is often missed but usually presents as a low grade fever, swollen lymph nodes (like glands that react to infection/inflammation) and decrease in some types of blood cells involved in immune system function.

The 2nd stage is a subclinical (no signs of illness) latent phase, how long this lasts depends on the strain of the virus and the age of the cat when they are infected.

Months to years after initial infection the 3rd stage, the immune deficient stage (like AIDS in humans) develops. Co-infection with FeLV (Feline Leukemia Virus) potentiates the primary and immune deficient stages.

Clinical signs of FIV can be due to direct effects of the virus itself (can damage kidneys, cause anemia and decreases in other types of blood cells, cancer of bone marrow, lymphoma, neurological problems with behaviour and eyes and diarrhoea due to small intestinal damage). Other clinical signs are caused by opportunistic secondary infection (susceptible to this because of immunodeficiency caused by the virus) affecting the skin, ears, gastrointestinal system, kidneys, brain, eyes, lungs, gums, respiratory and urinary tracts.

Behavioural changes include dementia, rage, hiding, inappropriate urination/defecation and roaming.

A test called and ELISA is available for FIV which looks for antibodies to the virus, if a cat has these antibodies they are referred to as “seropositive”. Occassionally cats with FIV do not produce these antibodies or the test is done before they’ve had a chance to and so these can come back as negative, termed a false negative as they do actually have the virus but the test has missed it. Another occasion when the test may not be accurate is in kittens less than 6 months that may have received antibodies in the milk from their mother. For these the test should be repeated every 60 days till it comes back negative. If they are still positive when they are older than 6 months then they are likely to be infected (other types of tests to grow the virus or detect it’s DNA can be done at this stage to confirm infection).

There is no cure for FIV, some anti viral drugs can improve clinical signs and prolong survival. FIV positive cats presenting as sick should be evaluated for other causes as secondary infection is common and treating this could resolve the clinical signs. The only way to know if an FIV cat has a poor prognosis is to treat the concurrent infection.

Prevention is best and this can be achieved by housing cats indoors to avoid fighting, NEUTERING and testing new cats before introduction to a household or cattery. The virus is susceptible to most disinfectants and dies quickly when out of the host, especially if dried.

If a cat has been potentially exposed it should be retested 60 days later to see if definitely infected.

Keep FIV positive cats indoors to prevent spread of the virus to other cats and to decrease the risk of opportunistic infection.

Kittens born to FIV positive mothers shouldn’t be allowed to nurse to reduce the risk of transmission in the milk and they should be seronegative at 6 months to be sure the virus hasn’t been passed on by the mother during pregnancy.

No vaccine for FIV in Ireland.