As its name suggests, Feline Immunodeficiency Virus (FIV) is closely related to the Human Immunodeficiency Virus (HIV) responsible for causing AIDS in people. There is no cure for either disease and the virus causes the gradual destruction of the white blood cells needed to protect the body against infectious diseases. However, the two viruses will only survive inside normal host species – in other words, there is NO risk of humans catching FIV from a cat, or vice versa. There is now a vaccine for the immunisation of susceptible healthy cats 8 weeks of age or older
FIV is found in the saliva and other bodily fluids of the cat. The main way that it passes between different cats appears to be through bites. It occurs more frequently in un-neutered tomcats than in neutered males and is found most often in strays and other free roaming animals. Female cats are generally less aggressive than males and are less likely to get involved in fights. However, a single bite may be enough to transmit infection and once it is there a cat in incapable of getting rid of the virus. The virus will also pass between generations; about one in four kittens born to an infected female carries the virus. Infection may pass from mother to kittens during pregnancy (through the placenta) or it may occur later as a result of the mother licking her offspring or biting the birth cord when they are born. Unlike HIV, there is no evidence that FIV is sexually transmitted.
In the first few days after it is infected your cat may show signs of ill health, such as a slight fever but it is unlikely that you would notice these minor changes. A cat that is already infected with the Feline Leukaemia Virus (FeLV) may show more severe symptoms. However, the cat soon appears to get better and may then be perfectly healthy for months or even years. Eventually it may become more susceptible to infection, resulting in variable clinical signs such as lethargy, swollen glands, a dull coat, fever and weight loss. Affected cats often develop inflammation of the mouth, discharging and inflamed eyes, anaemia and diarrhoea. Certain forms of cancer seem to be more common in FIV-infected cats and in a few cats the nervous system is affected, causing behavioural changes, convulsions, dementia etc.
FIV is more common in some areas than others depending on such factors as the population density, particularly of un-neutered male cats. However, random surveys of healthy cats show that up to six in every 100 cats carry the virus. In surveys of ill cats being treated at veterinary practices it is much more common – up to one in six ill cats can have the virus. Because of its long incubation period, the disease is most commonly seen in older cats between six and ten years old.
Until a cat starts to suffer a series of infections, as a result of its failing immune system, there is usually no reason to suspect that it is infected with FIV. A blood test has been developed to detect antibodies to the virus in apparently healthy animals. However, the tests are not effective for several weeks after infection because infection is not detectable for that length of time.
There is no cure for FIV and your cat is more prone to secondary infections. These can be controlled to some extent. For example, antibiotics will help against bacterial infections and steroids may reduce the wasting effects of FIV. In the long term it may be possible to treat FIV with antiviral drugs being developed against the human disease. Experimental studies have shown that they provide short-term improvements in some cats but the drugs are expensive and are not yet routinely available.
Cats that live in small, stable groups are less likely to fight and pass on the infection in a bite. However, if you have an infected cat that mixes with other healthy cats you may decide that it is safer to keep them apart. Having a tomcat neutered may reduce the risk of passing the disease to his housemates. Female cats with the virus should also be spayed to prevent the virus being passed to her kittens. If your cat dies as a result of FIV you may want to get another cat at some stage. As long as all the other cats in the home are healthy there is no significant risk to the new arrival. The virus quickly dies once it is exposed to the air and the new cat is unlikely to be infected from using the same feed bowl or litter tray, etc as its predecessor.
© Forrest Hill Vets (2000) Ltd