Experience with FeLV?

[lucicat]

I have four foster kittens and one just testing positive for FeLV--she is 8-10 weeks old. The other 3 were negative, so she's now quarantined and they all need retesting in 30 days. But neither I nor the rescue vet have experience with FeLV. I'd love to hear peoples experiences.
She's anemic and not gaining weight. . .I don't know if she'll survive and for how long, but I want to give here every chance she deserves. It's making the adoptions complicated though, as they are old enough to be adopted, but now with one positive and the other three exposed. . .
I'm just trying to learn what I can. Thanks.

 

[BlackCatOp]

Sorry to hear about the kitten’s positive FeLv test. I wasn’t sure if you were planning on re-testing all of the kittens but I would suggest re-testing the positive kitten too as it’s possible that the kitten could clear the infection. Also, especially, if an in-house test other than SNAP test was used for the initial testing. While the other in-house tests are great at ruling out FeLv, they are not good at detecting FeLv (thus the false positive rate is quite high (A positive result on Witness, Antgen and VetScan brand tests only has between a 24-52% of the cat actually truly being infected - assuming the average 5% prevalence)

If the kitten truly is positive, There are several clinical outcomes for the other kittens depending on each 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/Witness/Antgen/VEtScan: 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 retesting after 6 wesks may be: SANP -, IFA -, PCR +
• Abortive Infection: SNAP -, IFA -, PCR -

I hope the above makes sense. There is a lot to consider when diagnosing FeLv and unfortunately it is not straight forward. If you have any questions feel free to ask!


EDIT: Also the AAFP just released new guidelines this year. SAGE Journals: Your gateway to world-class research journals

 

[lucicat]

Sorry to hear about the kitten’s positive FeLv test. I wasn’t sure if you were planning on re-testing all of the kittens but I would suggest re-testing the positive kitten too as it’s possible that the kitten could clear the infection. Also, especially, if an in-house test other than SNAP test was used for the initial testing. While the other in-house tests are great at ruling out FeLv, they are not good at detecting FeLv (thus the false positive rate is quite high (A positive result on Witness, Antgen and VetScan brand tests only has between a 24-52% of the cat actually truly being infected - assuming the average 5% prevalence)

If the kitten truly is positive, There are several clinical outcomes for the other kittens depending on each 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/Witness/Antgen/VEtScan: 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 retesting after 6 wesks may be: SANP -, IFA -, PCR +
• Abortive Infection: SNAP -, IFA -, PCR -

I hope the above makes sense. There is a lot to consider when diagnosing FeLv and unfortunately it is not straight forward. If you have any questions feel free to ask!


EDIT: Also the AAFP just released new guidelines this year. SAGE Journals: Your gateway to world-class research journals

thank you, that is very informative and helpful! even from the things I've been reading online it's hard to get a clear picture of this disease.

She is a true positive, I know the rescue vet did the rapid test in house and when she got a positive she sent it our for further testing and it was really a positive. (Although I can't say for certainty the name of the tests). And yes, all four will be retested in 30 days. . .I am assuming she will stay pos and the boys will stay neg. I am hoping so.

 

[lucicat]

Sorry to hear about the kitten’s positive FeLv test. I wasn’t sure if you were planning on re-testing all of the kittens but I would suggest re-testing the positive kitten too as it’s possible that the kitten could clear the infection. Also, especially, if an in-house test other than SNAP test was used for the initial testing. While the other in-house tests are great at ruling out FeLv, they are not good at detecting FeLv (thus the false positive rate is quite high (A positive result on Witness, Antgen and VetScan brand tests only has between a 24-52% of the cat actually truly being infected - assuming the average 5% prevalence)

If the kitten truly is positive, There are several clinical outcomes for the other kittens depending on each 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/Witness/Antgen/VEtScan: 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 retesting after 6 wesks may be: SANP -, IFA -, PCR +
• Abortive Infection: SNAP -, IFA -, PCR -

I hope the above makes sense. There is a lot to consider when diagnosing FeLv and unfortunately it is not straight forward. If you have any questions feel free to ask!


EDIT: Also the AAFP just released new guidelines this year. SAGE Journals: Your gateway to world-class research journals

rechcecked the paperwork the rescue vet sent me. . .it was the IFA that was positive. So this means she has progressive infection?

 

[lucicat]

rechcecked the paperwork the rescue vet sent me. . .it was the IFA that was positive. So this means she has progressive infection?

The other 3 were negative on the SNAP test, but will be retested in 30 days

 

[BlackCatOp]

rechcecked the paperwork the rescue vet sent me. . .it was the IFA that was positive. So this means she has progressive infection?

That would be my conclusion as well. I’m sorry that she is truly positive. I don’t have any personal experience with actual FeLv cats but know it is not a kind disease. Sending best wishes that the boys will stay negative on repeat testIng.