Reptile & Amphibian Forums

I have a strange and confusing vet story...I have five cats and my friend has five cats too. We both keep our indoors, spay/neuter them and take them to same vet for the last couple of years. Every cat my friend and I've taking in gets tested for FIV and Leukemia before any contact with our other animals. She vaccinated all of hers and I did for all but the last two from the same litter (very stupid I know). A couple of her cats started getting sick (skinny, reclusive, and one with a respiratory problem) but the vet keep saying there was nothing wrong so she went to different vet. He sent some blood work away and here are the results. One FIV+ and Leukemia+, Two cats FIV+, and Two negative for both. After hearing that I got two of my cats retested too at a different vet. One (Vash) was FIV+ he was one of them that was already tested and vaccinated. The second (Bigby) was negative for both he was one of the two that was already tested but NOT vaccinated. Yesterday I finally started looking up information about FIV and happened to find this http://www.aafponline.org/news/statement_felovax.htm
Which says that most diagnostic tests can’t distinguish cats vaccinated for FIV with Fel-O-Vax and those that have FIV. So now I’m really confused?? I called my last vet and he said that Fel-O-Vax was used on Vash and that he would test positive but my new vet said that there are not false positives for FIV. I’m going to talk to my new vet again tomorrow to see what test they did but I was hoping to get an unbiased opinion. Who is right? Has anyone ever hear of this?

I've not heard of this, but I am pretty sure that there can be false positives for FIV. Ask your new vet to get in touch with the manufactures of the vaccine and ask about false positives. Also print out the webpage and give it to your new vet. S/he may just not be fully informed about this issue. There are a lot of things vets have to keep up with and something is bound to slip through the cracks every now and then.
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Smile, it will make them wonder what you are up to!

okay, i'll try to answer your questions, but first i need some more info.

you say that all your cats were vaccinated: what were they vaccinated for?

if all your cats and all your friend's cats were vaccinated for FIV, then it is true that they will forever afterwards test positive for FIV.

the tests used for FIV test for the antigen for the virus, and the Fel-O-Vax vaccine produces the antigen in cats receiving it. currently, there is research being done to find testing methods to differentiate the vaccine-induced strain of FIV from "naturally occurring" ones. for this reason, MANY vets will not use the FIV vaccine, because if the cat is ever lost or otherwise ends up in a shelter situation, it will test positive and it's likelihood of being adopted is slim. it is highly recommended that cats who have received the FIV vaccine be microchipped with that information included, so that if it DOES end up in a shelter, it has a chance to survive.

false positives for FIV are very common, actually--about 40% of cats who test positive on the snap/elisa test will test negative on the western blot test, which is currently considered the definitive test for FIV. most FIV sanctuaries will not accept a cat as an FIV without a positive western blot.

FIV cats, once neutered, are perfectly safe around other cats as long as they are not aggressive. (95%+ of positives are males, as it's only spread through DEEP, PENETRATING BITES, usually during fights over girls. the few females who get it generally do so during mating.) in the very few cases where a neutered male remains aggressive, filing down or extracting the canine teeth renders them incapable of biting deeply enough to transmit the virus.

i can link you to groups of folks living with FIV cats, as well as other resources if you would like!

PHCatByte
(this is Jess, my maine-coon FIV!)

Nearly all FIV vaccinated cats will give a false postive. It is because of the test looks for and what the vaccine is. When you test for FIV/FeLV you are testing for antibodies to the disease. Because FeLV is more common vaccine companies have made a vaccine that always to recognize FeLV if it come in contact with it, but to have antibodies always present. In other words it is mimiking the disease. FIV vaccines however are what are called killed virus vaccines. Meaning that they are the disease and so your cat will develope antibodies to the vaccine causing to give a false positive on a test.
If your cat aren't acting severly sick, I'm talking immunity problems, eyes problems in some cases blindness, extremely severe lethargy, chances are you have a false positive on your hands.
Remember FIV can only be transfered through DEEP penetrating bite wounds.