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My cat tested positive for Feline Leukemia. Can a vaccine cause this?

Updated on September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | neutered | 15 lbs

I've had a cat named boots for about 5 years now. He came to my door every night and I eventually took him in. I had to get him an emergency surgery last Sunday due to an anal absess. I went to the vet to get vaccines for first time and he tested positive on Feline leukemia. However, he's been neutered so we know he had a previous owner and most likely got vaccines prior. The vet said a previous vaccine could produce a false positive is this true? He shows no signs of being chronically ill.

1 Answer

Most Helpful Answer

Answered By David Darvishian

Veterinarian

Published on August 30th, 2017

Hi and thanks for using PetCoach! Sorry to hear about Boots. I have never personally heard that for Feline Leukemia. The vaccines for FeLV do not cause a positive test result BUT previous FIV (Feline Immunodeficiency Virus) vaccines cause a positive test result that cannot be differentiated from a natural infection. One positive FeLV test in a healthy cat is always suspect. False positives do occur and if you really want to know, I would advise that you go get a confirmation test done at your veterinarians office. The test is called an IFA or Immuno Fluorescent Antibody test and this is specific for FeLV. This disease along with FIV are very complex and sometimes very confusing with respect to the results. Let me provide a website link here so you can learn more about these retroviruses in cats. Good luck with Boots.

https://www.catvets.com/guidelines/practice-guidelines/retrovirus-management-guidelines

1Pet Parents found this answer helpful

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