3 Inconclusive FeLV/ FIV tests?

HalleyHeroine

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Hi, I literally just joined this forum to ask if anyone has ever experienced anything like this before because it is driving me crazy.

I have a (almost) 2 year old female cat that has epilepsy and has been sick twice in the time that I have had her. Almost 2 weeks ago I took her to the vet for a upper respiratory infection and he suggested we test for felv/ FIV because of her history and she hadn't been tested before.

They did a snap test and the vet was unsure of the result because of how the negative control dot developed. He said he's done thousands of these tests and never saw it develop before. According to the instructions if the felv/FIV dot was darker than the negative control dot then the test is positive. They were very close in color but it did look like test would indicate she is positive for both. They did a second snap to be certain and it was the same. So they drew more blood to send to the lab, which would take 7-10 days.

They just called today and said they were also uncertain of this result. He said it looked like she was positive for one and not the other but they couldn't be sure so we are going to draw more blood tomorrow and send this 2nd sample to the lab again.

Has anyone else ever had this much trouble getting results for felv/FIV before? They h
 

kittyluv387

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I can say the snap test isn't extremely accurate for FELV. False positives aren't that rare. One of our cats got a false semi positive. We confirmed with an IFA and also a PCR that she does not have FELV, dormant or otherwise.
 
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HalleyHeroine

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I can say the snap test isn't extremely accurate for FELV. False positives aren't that rare. One of our cats got a false semi positive. We confirmed with an IFA and also a PCR that she does not have FELV, dormant or otherwise.
Thanks for the reply. It does certainly look like something is false because the SNAP indicates both and the lab indicated just one of the two. (I don't know which, it was just a quick phone call to set up an appt for tomorrow). But honestly they don't know anything for sure. And I am not sure if what was done at the lab included a IFA or if it was something else. It is just very concerning and frustrating that my cat has had blood drawn 3 times and it is two weeks later and we still don't have any solid information.
 

kittyluv387

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Thanks for the reply. It does certainly look like something is false because the SNAP indicates both and the lab indicated just one of the two. (I don't know which, it was just a quick phone call to set up an appt for tomorrow). But honestly they don't know anything for sure. And I am not sure if what was done at the lab included a IFA or if it was something else. It is just very concerning and frustrating that my cat has had blood drawn 3 times and it is two weeks later and we still don't have any solid information.
Right. But if you want to start ruling anything out those are the tests you should ask for. If your cat has always been indoors I would go ahead and ask to get a PCR for felv.
 
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HalleyHeroine

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Right. But if you want to start ruling anything out those are the tests you should ask for. If your cat has always been indoors I would go ahead and ask to get a PCR for felv.
Ok. I had not heard of a PCR before, just a IFA. I will find out tomorrow what exactly was done with the first lab sample and request those. Thank you for your help.
 

kittyluv387

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Ok. I had not heard of a PCR before, just a IFA. I will find out tomorrow what exactly was done with the first lab sample and request those. Thank you for your help.
Np. Thing with IFA is that it's possible for false negatives if the virus is laying dormant. The PCR will catch both. If a cat has been exposed to strange cats or been going outside it's best to wait a few months to run a PCR because the virus has to take its course first. But if your cat doesn't go outside and you haven't brought home any new cats recently it's safe to test him.
 

BlackCatOp

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Sorry to hear your kitty has been sick. Unfortunately, diagnosing FeLv can be frustrating at times.

There are several clinical outcomes that FeLv can cause depending on the cat’s immune system. Understanding the different infection outcomes help with understanding the different testing modalities.

  1. Progressive Infection: The cat does not develop an adequate immune response (ie no antibody production) and FeLv infection is not contained by the cat’s immune system. The virus replicates extensively and 80% of cats with progressive infections will die within 3 years from anemia and secondary infections.
  2. Regressive Infection: Cat is able to develop an adequate immune response but not before virus has integrated into the cat’s genome (FeLv is a retrovirus). There is some initial viral replication and then the cat’s immune system is able to keep the virus incheck. If the cat becomes stressed or immunocompromised then the virus can resume replicating.
  3. Abortive Infection: This scenario most commonly occurs when cat is exposed to a low amount of virus. Cat has an adequate immune response (antibodies) and viral replication never occurs.

Testing modalities
  • SNAP/ELISA: An antigen based test detecting a protein found on the virus protein coat (generally takes 30 days for cat to test positive after exposure to virus. Result can revert to negative in Abortive and Regressive infections depending on when the cat was tested and what stage of infection the cat is undergoing.)
  • IFA: A test for detecting viral antigens within infected lymphocytes (positive result indicates virus is replicating, cat is shedding virus and cat is considered contagious)
  • PCR: Tests for presents of viral DNA (positive result indicates viral DNA has integrated into cat’s genome but does not indicate viral shedding/replication/contagious)

Testing outcomes:
  • Progressive Infection: SNAP +, IFA +, PCR +
  • Regressive Infection: SNAP initially pos but retest at 60 days may be neg, IFA -, PCR +
  • Abortive Infection: SNAP -, IFA -, PCR

As far as FIV, testing is much simpler since the SNAP test is antibody based. As long as the cat is not a kitten and has not received vaccinations for FIV, a positive result indicates exposure to FIV.

Of course this is all in the ideal world and most cats don’t read the textbooks so your experiences may vary, lol.

Best wishes for you and your kitty!

Medical Disclaimer: My comments are not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your cat’s medical condition. Never disregard your veterinarian’s treatment or delay obtaining help because of something I have posted.
 
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