Dealing with FIV and FeLV in cats


FIV (Feline immunodeficiency virus) is usually acquired by uncastrated males fighting for territory so is quite common in communities of feral cats; almost all the FIV positive cats we have come across have been adult males.  Once they are castrated they are less aggressive and in a good home with regular meals they usually become less territorial. 


A cat which tests positive for FIV is by no means an unhealthy cat.  The virus means the immune system may be compromised and not respond as readily to fight any infection but in many cats it causes no problems at all.  In fact, in a home environment, with a good diet, and annual booster vaccinations, most FIV+ cats probably live a normal lifespan. The virus is not transmittable to humans or other animals.


In the past, it was always advised that FIV+ cats should only be kept with other positive cats and should be kept indoors.  These days many people have ‘mixed’ households with both FIV+ and non-FIV cats; recent research shows that the rate of transmission between these cats is less than 5%. Provided the FIV+ cat is not aggressive there should be no problem; the virus is almost never passed by sharing food bowls or litter trays, but almost always by the infection of wounds during fighting.  It was also advised that FIV+ cats should be ‘inside only’ cats – very difficult for a cat which has lived most of its life outside.  If the cat is in the countryside with lots of outside space and few other cats around then it may be possible to give such a cat a good life with little risk of transmitting the virus or exposing it unduly to infection from other cats.


FeLV (Feline Leukaemia Virus) 

A cat which tests positive for FeLV (Leucose) may stay healthy for a good number of years if it is well fed and cared for.  However, the virus is mainly spread by everyday contact with other cats and by sharing food bowls and litter trays.  Even if other cats in the household are vaccinated against leucose they are not necessarily 100% protected so it is wiser to keep an FeLV+ cat on its own or with other cats who have the virus and they should not mix with other cats outside. The virus is not transmittable to humans or other animals.


Any cat aged over six months and in the care of the association is tested for FIV and FeLV as this information is important when finding a home for the cat.

We do not test our kittens for FIV/FeLV.  Kittens that test positive for FIV probably do NOT have FIV! A mother cat with FIV will have FIV antibodies which are produced by her immune system in response to the virus. When pregnant, an FIV mother will pass these antibodies to her kittens through the blood, but she will not pass the virus, which will not cross the placenta. Because the usual test for FIV actually looks for the antibodies and not the virus, a kitten from an FIV mother will show positive on the test without any virus being present. As the kittens grow, they will gradually lose their inherited protection, and will then test negative. This can take several months – the actual time varies between kittens – so any FIV positive test is not safe until the kitten is at least six months old. Kittens who really are FIV positive are not common.

Kittens may be born with FeLV but our experience has been that these kittens are generally sickly and fail to thrive.  If they are poorly and do not respond to the usual treatments then they may be tested as part of the search for a diagnosis.


All our kittens are microchipped before adoption, generally around 9-10 weeks of age. At the same time they receive their first vaccination, against typhus, calcivirus, herpes and leucose (FeLV).  At present there is no generally available vaccine against FIV. If the kittens are still in foster, they will receive the booster four weeks later – otherwise this will be the responsibility of the adopter.