Testing Whether a Cat Has FeLV or FIV
CatChannel and CAT FANCY veterinary expert Arnold Plotnick, DVM, shares information on vet tests and what cat diseases they uncover.
Arnold Plotnick, DVM |
Posted: November 4, 2011, 3 a.m. EDT
Q: I got my 2½-year-old tabby cat from a shelter when she was 10 weeks old. I bring her often to our veterinarian who specializes in cats.
While my cat and I were away, a local vet in examined her for a checkup. I felt the trip and the new surroundings were a bit stressful to her. The vet conducted a feline leukemia test (which I never asked for); this was apparently their standard procedure for new patients. To my shock, they said my cat was positive for feline leukemia. Upset and hoping for a mistake, I took to my cat to her vet and for another test and saw evidence of being positive. Twice, we did a Western Blot test and it came back undeterminable. I’ve looked up online and read that it’s possible for baby kittens that get it from their mother can sometimes outgrow it. I feed her a healthy holistic diet and read that it’s the nutrition that can help them overcome this disease. Is this true?
A: I’m sorry to hear that your cat tested positive for FeLV. Most shelters test their kittens for FeLV and FIV before adopting them out. I’m surprised that your shelter did not. Or maybe they did, but you lost or did not remember the results. In any event, if they didn’t test her, I would have expected your regular vet to have tested her while she was a kitten.
If your cat has not been exposed to any other cats who could have transmitted FeLV to her, then she must have already been infected at the time you adopted her. In my experience, a 10- week-old kitten with FeLV is very unlikely to survive and do well until the age of 2½ without any signs of illness. The vast majority of kittens with FeLV rarely survive kittenhood.
The test that the first vet in performed was probably an in-house test known as an ELISA test. It gives results in 10 minutes and is a pretty accurate test. Because a positive test has potentially dire consequences, any positive test should be confirmed, to rule out the possibility of a false-positive result. A second blood test should be performed, ideally using a test from a different manufacturer.
To me, the in-house ELISA test confirms that your cat is positive. Alternatively, a test can be performed that looks for the presence of the leukemia virus within infected blood cells, rather than circulating within the bloodstream. This test, performed on blood smears or on a bone marrow sample, is known as an IFA (immunofluorescence) test. A positive IFA test not only confirms that the cat is infected with FeLV, but that the cat’s bone marrow has been affected – a progressive infection. You, interestingly, mentioned the “Western Blot” test. This test is not commonly performed to confirm a FeLV infection. This test is used to confirm a FIV infection.
I have a feeling you have your viruses confused. I suspect your cat tested positive for FIV, not FeLV. The FIV test is an antibody test. Because kittens get their antibodies from their mother, a positive test may not mean that the kitten is infected, because those antibodies came from the mother. It suggests that the mother is infected. Most kittens born to a FIV infected mother are not themselves infected. After six months of age, any antibodies obtained from the mother through the milk will no longer be present in the kitten’s bloodstream.
If your cat tested positive at 2½ years of age, on two different occasions, then I suspect she truly is positive. On occasion, the confirmatory test – the Western blot test – will come back “indeterminate.” This is an ambiguous result that is hard to define. In my experience, most cats that test indeterminate eventually will test positive on the test at a later date. For all practical purposes, you should consider your cat FIV positive. Don’t be too discouraged, though. Cats with FIV can live long, relatively healthy lives. The fact that you take your cat to the veterinarian often is a good thing. Your vet can advise you as to the best ways to take care of a cat with FIV.
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Testing Whether a Cat Has FeLV or FIV