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What is Feline Leukemia (FeLV)?

Feline leukemia virus (FeLV) is a retrovirus that infects cats. FeLV can be transmitted from an infected cat to a non-infected cat by way of saliva or nasal secretions. This disease is often referred to as the "licking disease." If not defeated by the animal’s immune system, the virus can be lethal. 


How is FeLV spread?

Cats persistently infected with FeLV serve as sources of infection. Virus is shed in very high quantities in saliva and nasal secretions, but also in urine, feces, and milk from infected cats.  Cat-to-cat transfer of the virus may occur from a bite wound, during mutual grooming, and (though rarely) through the shared use of litter boxes and feeding dishes. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing. FeLV doesn't survive long outside a cat's body - probably less than a few hours under normal household conditions.


What does FeLV do to a cat?

Feline leukemia virus adversely affects the cat's body in many ways. It is the most common cause of cancer in cats, it may cause various blood disorders, and it may lead to a state of immune deficiency that hinders the cat's ability to protect itself against other infections. The same bacteria, viruses, protozoa, and fungi that may be found in the everyday environment, where they usually do not affect healthy animals, can cause severe illness in those with weakened immune systems. These secondary infections are responsible for many of the diseases associated with FeLV.



How is infection diagnosed?


Two types of FeLV blood tests are in common use. Both detect a protein component of the virus as it circulates in the bloodstream.


  • ELISA (enzyme-linked immunosorbent assay) and similar tests can be performed in your veterinarian's office.  This test is often called a "snap test."

  • IFA (indirect immunofluorescent antibody assay) tests must be sent out to a diagnostic laboratory.  This test determines if the virus has mutated into the cat's bone marrow which usually indicates the virus has made its way past the immune defenses and is permanent.

Each testing method has strengths and weaknesses. Your veterinarian will likely suggest an ELISA-type test first, but in some cases, both tests must be performed - and perhaps repeated, to clarify a cat's true infection status. 


How long do FeLV-infected cats live?


It is impossible to accurately predict the life expectancy of a cat infected with FeLV.  With appropriate care and under ideal conditions, infected cats can remain in apparent good health for many months, although most succumb to a FeLV-related disease within two or three years after becoming infected. At Leuk's Landing, we have had a few kitties live to eight years of age but the average is two years. Kittens are often challenged to live to their first birthday because of the disease.


Can I give a non-infected cat the FeLV virus after touching an infected kitty?

Feline leukemia virus will not survive outside the cat for more than a few hours in most environments.  Washing hands after touching a kitty with the virus should keep you from giving it to a healthy kitty. If an infected kitty sneezes or drools on you or your clothing, washing your clothes is recommended.       


Can people become infected with FeLV?

Epidemiological and laboratory studies have failed to provide evidence that FeLV can be transmitted from infected cats to humans.

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