What is it?Feline Immunodeficiency Virus (FIV) is a contagious viral disease of cats. It is thought to affect around 4% of cats in the UK. It has many similarities to the human immunodeficiency virus (HIV) which causes AIDS in humans, but FIV only affects cats and is not a risk to human health. The FIV virus damages the cells in the cat's body that fight infection (the immune system). Signs of FIV infection can take a long time to develop, and FIV infected cats can live comfortably for a number of years. However, the effects of the virus on the immune system are serious, and infected cats are more likely to suffer from secondary infections.
What is the risk?
FIV is spread in the saliva and other bodily fluids of infected cats. Cats become infected by FIV usually through a bite from an infected cat. Unneutered male cats who fight over territory are more likely to be infected with FIV, and it is relatively common in the stray cat population. The virus does not frequently infect the cat's environment as it cannot survive for long outside the cat, but one bite from an infected cat can be enough to transmit infection. Indoor only cats are much less likely to become infected with FIV.
Unlike HIV, FIV sexual transmission does not seem to be an issue, but if a pregnant cat is infected with FIV, the virus may infect the kittens. Only a small minority of kittens born to FIV infected mothers will have FIV, but the mother may pass on antibodies against FIV to the kittens. For this reason, it is usually recommended to blood test kittens for the presence of FIV virus after 6 months of age. FIV is closely related to Feline Leukaemia Virus (FeLV) and while a cat with FeLV will not automatically become infected with FIV, if they do contract FIV, the disease will be more serious.
What happens to the cat?Once infected, in the vast majority of cases, the cat cannot get rid of the virus. The first signs of infection may go unnoticed - the cat may be a little quiet and feverish for a couple of days. Over time, the virus damages the immune system by attacking cells that are involved in controlling infection. FIV infected cats are therefore more prone to developing secondary infections such as skin, urinary tract, respiratory, diarrhoea, and dental infections. This may, however, take months or years to develop.
How do you (the vet) know what is going on?Signs of infection:
Diagnosis is by blood testing for antibodies to FIV virus. No test is 100% and antibody testing occasionally may give false results. If the result is not clear, the cat's blood can be tested for the presence of the FIV virus itself, which is conclusive. Cats that are FIV positive are able to transmit the disease to other cats.