Do Cat Vaccines cause Cancer?

This is something you hear horror stories about from pet owners - they get annual vaccines for their pet, and then suddenly find out that their cat has gotten cancer from one of the vaccines. This one isn't an urban legend, it's true. It's often called "Vaccine Associated Sarcoma" or VAS. Many vaccines can cause a pretty high rate of cancer in cats - estimates range up to 1 in 1000. The common ones that cause it are versions of the rabies vaccine and the feline leukemia vaccine. This is a cat specific issue, so dog owners can breathe a sigh of relief.


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What can you do to avoid this?

You've got a couple of options. Discussing it with your vet is the first thing to do - avoiding the vaccines may not be a viable option for you just because many state laws require you to have certain vaccines for vets to see your pet. For example, I took my cat into the vet in Texas and was told I had to get a rabies vaccine before they could look at her tooth. Turns out it's mandatory - but they forwarded me to another vet who gave less dangerous versions of the rabies vaccine. I was a little annoyed at the whole process simply because my cat is not allowed outside - there is virtually no risk of rabies, and if she ever got lost outside on her own she honestly wouldn't last long anyway. But it's mandatory, so the best options you have are to try to do them less frequently and to try to get the safer version. A general term you can ask about is "non-adjuvant" vaccines - these are developed by some manufacturers to avoid the cancer-causing elements of the vaccines. If you live close enough to a state border of another state with different laws, you might consider going there to get your checkups if it's not an emergency.

There are a couple of online resources you can take a look at:

For a scholarly-type article arguing that it is often better not to vaccinate cats:

For a good advice page on cat vaccinations by a vet:

For an advice site on the issue made by the owner of a cat that contracted cancer from a vaccine:

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Text copyright 2005-2006 and may not be reproduced without consent. This is not the official web page of any of the products listed on this site, this is a review page created by an individual. It is not by a vet, and is meant to be informative and not to substitute for a vet's advice - always consult a vet if you suspect a health problem.