Feline Leukemia virus (FeLV) is a relatively common disease agent among unvaccinated cats. Infection with this retrovirus remains the leading cause of death in cats. The virus is transmitted by the saliva of infected cats contaminating the mucous membranes of uninfected cats by licking the eyes, nose, mouth, OR through bite wounds; direct transfer from the mother to the unborn fetus; or by transmission of infected blood to an uninfected cat.
Eighty-five percent of non-immune (unvaccinated) cats that contract the virus will die within three years. Feline leukemia virus is the leading cause of cancer in cats, it can cause various blood disorders and, it can also cause severe immunosuppression. The virus spreads to the bone marrow where production of red blood cells and certain white blood cells is impaired or degenerative. The decrease if red blood cell numbers causes anemia. Without the normal white blood cell production, the immune system is unable to function at the optimal level which causes an immunosuppressed state. The body is unable to fight off infections, and if the immunosuppression is severe enough, the infections will overcome the immune system and the kitty will die.
Many cats that are exposed to the virus have a latent infection. This means that the virus is essentially hiding within the body and can linger for many years. The cat, however, will continue to shed viral particles in the bodily fluids (mucous, urine, feces, saliva, tears) and can, therefore, still infect other cats. There are a few cats that are able to mount an effective immune response early into this stage and actually eliminate the virus from within the bloodstream (viremia). However, it is important to understand that the majority of cats are not able to clear the viremia and eventually succumb to the infection.
The signs of FeLV vary and depend on the severity of infection. Your cat may exhibit lethargy, inappetance, slow and progressive weight loss, enlarged lymph nodes, dull hair coat, persistent fever, pale mucous membranes (gums), inflammation of the gums (gingivitis) or mouth (stomatitis), skin, bladder and/or respiratory infections, diarrhea, seizures or other neurologic disorders, eye conditions.
FeLV can be detected in a simple and accurate blood test that can be performed in the veterinary office, and any positive diagnosis would be verified with a second test. In the past, there were no curative medications for FeLV, however now there are some chemotherapy and anti-viral drugs that have helped some cats. These treatments are costly and do not work for every patient. More common current treatments are designed to provide supportive care and comfort.
The good news is that an excellent vaccine is available to prevent your kitty’s infection with FeLV. First, any kitten or adult cat with an unknown history should be tested. If an adult is negative, she may be vaccinated in a series of two. She should be revaccinated annually with a recombinant vaccine if there is a continued risk of exposure. Young kittens (under 6 months of age) should have several tests performed as new research shows that some kittens do not develop a high enough antigen level for the test to show a positive result. Kittens also must be vaccinated in a series of two vaccines with an annual booster. Please note that no vaccine, no matter how effective, is a 100% guarantee that an animal will not contract the disease for which it has been vaccinated.
Cats that live outdoors are at a much higher risk of exposure from other cats as these kitties are much more likely to be involved in a cat fight. Kittens in general are more susceptible to infection than otherwise healthy adults.
In a FeLV positive household, no new cats should be introduced while there is still a positive cat present. Feline Leukemia virus is considered an unstable virus and so does not live more than a few minutes to hours outside of the host and it is easily killed by most disinfectants.
For more information that is tailored specifically to your pet, or to answer any questions that you may have, please contact your veterinarian
Robin Paterson, D.V.M.
Cerbat Cliffs Animal Hospital
4110 Stockton Hill Road
Kingman, AZ 86401