Feline Leukaemia Virus


As a retovirus, the Feline Leukemia Virus is commonly mistaken for being the same as the feline immunodeficiency virus despite there being quite a few differences. Once infected the disease infects the host for the rest of its life and cats usually die within three years of being diagnosed. The virus enters the lymphatic tissues and briefly travels through the blood stream to the intestines and bone marrow. The most detrimental effect of the feline leukemia virus is to suppress the cat’s immune system. Cats are more susceptible to catching the disease if they have a weak or underdeveloped immune system, such as kittens or cats in poor health. Vaccines are strongly encouraged for healthy cats as, although it does not protect all cats, it reduces the chance of infection and transmission.


Feline leukemia virus is transmitted via prolonged exposure to infected saliva or nasal discharge. This can usually happen, for example, if a healthy cat shares the same feeding or water bowl as an infected cat. Infected urine and faeces are also known to transfer the virus and colostrum ingested by the kittens of an infected queen is another source of transmission. Objects in the environment contaminated with the virus, such as food bowls, may be a cause of infection although the virus cannot survive for a long period of time outside of its host.

When introducing a new cat to a household where the previous cat died as a result of infection from the feline leukemia virus, then all inanimate objects should be disinfected against other diseases. This is because, although the FeLV does not survive in the environment for long, other dangerous viruses do which the deceased cat may have contracted in its weakened state. The new cat should be properly vaccinated.


The disease shows no symptoms in the cat for sometimes as long as a few years. When they do present themselves, the cat visibly deteriorates in health with signs such as a lack of condition in its coat, enlarged lymph nodes under the jaw, and pale gums. There will be a loss of appetite, fever and a resultant weight loss. Gingivitis and stomatitis become visible and the cat may experience diarrhoea, behavioural changes and occasionally neurological problems including seizures. Conjunctivitis may occur and in some cases pregnant queens undergo abortions.

Though not a cancer itself, despite the misnomer as a result of the time it was discovered, cancers can develop as a result of it. Symptoms from secondary infections are also often presented.

Treatment and Prevention

There is no cure for the disease and stray or feral cats with the disease are often euthanized. Owners who do not want their cats put down are advised to isolate the infected pet within the home to prevent the spread of this serious disease. Vaccination is essential for cats that are able to go outside though may not provide protection to every cat. The vaccine cannot be given to help cure an infected cat.

Diagnosis and Prognosis

The ELISA test is the preferred method of diagnosis sometimes followed by IFA tests. They are used for the detection of a protein, which is a section of the virus, in the blood. Most cats are euthanized immediately or until as long as three years after a positive diagnosis for the disease. Others die within this time usually from catching a lethal disease since the virus compromises the immune system. Such diseases include progressive anaemia, leukaemia or lymphoma.


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