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Feline Leukaemia Virus (FeLV) is a serious and fatal disease affecting cats. About one in three cats that come into contact with the virus develop a permanent infection, which is almost always fatal. FeLV infection causes a wide range of symptoms and by weakening the body’s immune defences it can make cats more susceptible to other infectious conditions. FeLV can cause a variety of cancers including lymphoma and a true leukaemia that attacks the bone marrow.


How is the disease spread?

The Feline Leukaemia Virus is present in the bodily fluids of affected cats, most commonly on the saliva. The virus may be spread when cats groom each other, share the same food bowls or litter tray, sneeze on or bite another cat. Other less common but possible routes of infection are during sexual relations and between a mother and kittens, either within the womb or in the maternal milk.


Is my cat at risk of catching FeLV?

On average about one in every hundred cats has a persistent infection in which the active virus is permanently present in its body. The risks are much higher when several cats live under one roof, or in areas of high population density. The chances of being exposed to the virus increase with age.

However it is young animals that are most likely to be infected with the virus, and one in three of these animals will go on to develop the disease.


What are the effects of FeLV?

FeLV cats generally have a short life expectancy. Most cats die as a result of destruction of the white blood cells that are one of the main bodily defences against disease. This leaves the cat wide open to infection from any one of a range of other germs. FeLV can also cause anaemia, and a proportion of infected cats develop cancer.

The clinical picture can be very similar to those cats infected with Feline Immunodeficiency Virus (FIV). Symptoms include infertility, abortion, stillborn or very weak kittens, inflammation around the eyes, rapid weight loss, gut disease or nerve damage. An infected cat may appear healthy for several months, but about eight out of ten cats are dead within three years of being infected by the virus.


Can an infected cat be identified before it becomes ill?

FeLV must be suspected where your cat is affected by a succession of different disease conditions. There is a simple blood test to show whether or not your cat has had contact with the virus. However a positive result is not always disastrous – it may just mean that your cat has been infected but is now resistant.

Similarly a negative result is not an all clear – if the infection was recent your cat may not have reacted (produced antibodies) to the virus. Therefore we usually need to take 2 tests a few weeks apart to give more reliable information about your cats state of health.


Can FeLV be treated?

There is no way to stop an infection once it has become established. Medical treatments may make your cat more comfortable or help tackle other infections that may occur as a result of FeLV. Vaccines can reduce the likelihood of your cat contracting the disease. The vaccinations are given at 9 and 12 weeks of age, and annual boosters are required to maintain protection. Vaccination is no use if the virus has already infected your cat.


Are FeLV vaccines harmful?

The vaccines are very safe, but a reaction, such as lumps forming at the injection site, may occur in rare cases. If your cat is the only one in the household and spends ALL of its time indoors, there is no risk of contraction of the virus and vaccination for FeLV is unnecessary.


My cat has tested positive for FeLV – what should I do?

If two consecutive tests a few weeks apart show antibodies to FeLV it is safe to say that your cat is infected. A sick FeLV positive cat may be treated symptomatically, however euthanasia must be seriously considered if they do not enjoy a good quality of life. Healthy FeLV positive cats may continue to live in good health for a reasonable period of time.

They should be given the same level of care as an uninfected cat, but additionally should be shielded from cats with other diseases and stress should be kept to a minimum. They should be kept away from other cats in your home even if they have been vaccinated, and must NOT be allowed to wander outside. If it is impossible to keep your cats apart, it may be better to find it a new home where it is unlikely to pass infection on to other cats.

Should your cat pass away and you would like another cat, your new cat is unlikely to be at risk from lingering infection in the home. The virus does not live long outside an infected cat but to be safe all feeding bowls, litter trays etc should be replaced or washed with hot soapy water, and surfaces washed with a weak solution of bleach before introducing your new cat into the household.