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Feline Leukemia - FeLV - Overview



     This is a serious disease in cats, caused by a virus infection.  It is also a complex disease, of which leukemia (cancer of white blood cells) and cancerous tumors are only a small part.  Various other related but non-tumorous diseases are also involved.  They include anemia, atrophy of the thymus gland, ulcers of the mouth, skin lesions, reproductive problems such as miscarriages and weak or dying kittens (fading kitten syndrome), chronic digestive and respiratory problems, and others.
     The feline leukemia virus impairs the cat's immune system similar to the way the AIDS virus affects humans.  As a result, cats lose their ability to fight the bacteria, viruses and fungi which cause these disease problems.
     Feline Leukemia is spread by direct contact with infected cats.  It is usually transmitted in the saliva, but low levels of the virus can also be found in urine and feces.  Licking, biting and sneezing are common forms of transmission.  Food and water dishes and litter boxes are likely sources of infections, if healthy cats share them with infected cats.
    The only sure way to know if your cat has the disease is to have it tested by a veterinarian.  Because such a complex of disease problems and symptoms is involved, it is not easy to spot the disease by how your cat looks or acts.  However, certain signs - such as long-lasting infections, unexplained weight loss, reduced appetite, swollen glands or gum problems - should alert you to a health problem that warrants a closer look by your veterinarian.
     Once a cat has been infected with Feline Leukemia virus, there are three possible outcomes:

1 - About 40% develop an immunity and become resistant to future infections.
2 - About 30% become "latent carriers" of the disease, neither fully recovered nor seriously affected.  They may be susceptible to the disease at some future time, and, if reactivated, they can pass on the virus to their offspring.
3 - The remaining 30% of exposed cats are persistently infected and, of these, about 83% die within three years of the time of infection from leukemia and/or the associated diseases.  Death can be sudden or lingering and painful.

     To prevent your cats from getting the disease the most obvious is to limit or eliminate all contact with other cats.  However, this isn't always possible or practical.  The best solution is to a veterinarian and have your cat or cats vaccinated with the most effective and safe vaccine available.  The majority of cats show no adverse response to Feline Leukemia vaccination.  However some cats will develop a temporary fever, listlessness or reduction of appetite.  When they occur, these responses normally disappear in 24-48 hours.  In the unlikely event that your cat develops other symptoms after vaccination, you should call your veterinarian.
     No evidence currently links FeLV in cats with any known human disease problems.