Should My Cat Get the Feline Leukemia Vaccine?

When the FeLV was introduced, it was seen as a health breakthrough. Times have changed.

By: rossco92
Only 1% of strictly indoor cats get FeLV. By: rossco92

Although the vaccine for preventing feline leukemia is not terribly effective, cats are routinely vaccinated against the disease. Problems can arise from the vaccine itself, however, causing severe adverse reactions.

These possible complications often prompt the wary cat owner to ask, “Should my cat get the feline leukemia vaccine?”

  • Indoor-Only: People indoor-only felines can probably consider themselves OK by not giving the vaccine, since only 1% of strictly indoor cats get the disease.
  • Indoor/Outdoor: But those with indoor/outdoor cats or outdoor-only cats (who will run a greater risk of exposure to the disease) need to compare the risks with the benefits before deciding what is best for their feline pets. Thirty% of cats allowed to go outside wind up contracting an acute type of feline leukemia, so veterinarians strongly recommend the vaccine.


According to It’s a Cat’s World — You Just Live in It, the vaccine is very ineffective and most vets don’t bother administering it.

So to save yourself a lot of grief, blood-test any cat before adopting it. Some shelters test automatically, but always have the kitty tested by your own veterinarian just to be on the safe side. It is a simple test, requiring only a few drops of blood. The blood test results are back within minutes.

If your cat tests positive for feline leukemia, be certain that the result was not a false positive reading (test again). Leukemia will shorten a cat’s lifespan. The disease provokes an immune deficiency condition and quickly destroys red blood cells. It is usually fatal over the long term.

In this comprehensive video, Clair Thompson, VMD, explains all about “feline AIDS”:

Origins of the Vaccine

According to The Nature of Animal Healing, the feline leukemia vaccine first appeared in 1985. It was widely welcomed, as the virus had killed thousands of cats since it had emerged two decades earlier. FeLV, as the disease is known, can be carried by cats with no visible signs. Then, other cats can become infected through saliva, via mutual grooming.

Most vets were initially thrilled about the new vaccine and used it on many cats they treated.

Always Blood-Test First

But here is the thing about the vaccine that has made it fall so far out of favor: Administering the FeLV vaccine may actually stir up the virus if it is already lying low in your cat (and you are not aware that your cat already has the virus). Then, spilling into the bloodstream, the newly awakened virus could cause full-blown leukemia before the vaccine can halt it.

This is why initial blood-testing is highly recommended — test before your cat is given the vaccine. Once you can be absolutely positive that your cat doesn’t already have the virus, you can then get the vaccine in hopes of preventing any future transmission.

So, to sum up… Should your cat get the feline leukemia vaccine? Only you can make that decision. Let your trusted veterinarian guide you in this difficult choice, and know that you will always have your pet’s best interests at heart.

Additional Resources

Gayle Hickman

View posts by Gayle Hickman
Gayle Hickman has been researching and writing about pet behaviors since 2011. In addition to Petful, her articles have appeared on Reader's Digest, Yahoo Shine and WebVet, to name a few.

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