Feline Leukemia Confusion

So, after many years of not having a cat, I decided to bring one in to my home again.  I took my time, did my research and decided this time to get exactly what I want rather than just taking whatever came along as I'd always done in the past.  I'm a sucker for strays and shelter animals, but for once in my life I actually wanted to choose and get just what I wanted.  So I picked a local breeder and got on the waiting list for a fall kitten.  I put it off that long because it was going to be a busy summer and I didn't want the new addition to spend time alone right off the bat.  I really tried to do everything just right.

Just when I was sure I'd done all my homework and was on the right track, my teen daughter comes home with a stray kitten.  Ugh.  I figured fine, I guess my expensive hand picked kitten will have a playmate.  It was the middle of the busiest week ever and like I said, I've always had a soft spot for strays so I didn't fight her.  Because we were so busy though, it was about a week before we got it to the vet. She took it herself, got it wormed and treated for a bad, bad flea infestation.  It was too young for vaccinations yet.  We had to bomb the house because of the fleas but finally everything seemed ok.

So today, nearly 2 weeks after she took it in, I asked her when it was due to go back and she said it was supposed to get a test redone in 30 days and handed me the Feline Leukemia info sheet.  What????  The kitten is FLV positive??? 

What does this mean for the kitten I have coming in a couple months?  It'll have one vaccine before I get it but aren't two required for immunity?  Do I need to see if the breeder will keep it an extra 3 weeks for the second dose to be administered?  Does this mean they can't be together?  My apartment isn't that big, I can't segregate them very well.

She said the vet said something about the kitten "becoming immune" on it's own, and that's why the retest?  What does that mean?  Is that possible?  All the info on the web is confusing and conflicting.  As best I can tell the kitten is about 7 to 8 weeks now, meaning the test was done at 5 or 6 weeks.  It's mom/dad were strays at best, maybe even ferrell, though she did drop the kitten under some lady's back deck, which is where my daughter got it.

What's the scoop on this?  Can it go from positive to negative on it's own?  When is the test conclusive? 

How many series will the new kitten need before it's immune and safe to live with this one?  Will it ever really be safe? 

Sorry for all the crazy questions, just wasn't expecting this.

Yes, false positives are common in young kittens. I'm not even sure the re-test will be accurate at this age, I think they have to be at least 4 months old for it to be really accurate.

that the kitty will be negative for FeLV! If not, you would have some hard decisions to make. I don't think I'd bring a kitten into a home with a FeLV+ kitty. The breeder might not allow it anyway.

Miss Beth, I can understand your confusion. I was not exactly in the same situation - for me it was adding a cat to the two I already had. But a feline leukemia diagnosis got me really thinking about testing for the virus. What I did was wait five months for Wilbur to test negative twice as a third test was required when the second test conflicted with the first. It does not matter to me whether Wilbur developed immunity or the test result was wrong. Either way, he never had FLV after he chose me to adopt him and that is all that matters. However, I did read about the fact that test is only 80% accurate and how cats can develop natural immunity when the virus is dormant.

BTW Wilbur was several years old when he was tested, so the high risk of false positives apparently is not specific to kittens.

missbeth said:

What does this mean for the kitten I have coming in a couple months?  It'll have one vaccine before I get it 

Click to expand...

How old will the new kitten be? It's standard for kittens to be kept for at least 12 weeks, allowing for full vaccination before going to their new homes.

As already said false positives can occur, it's recommended to screen them 12 weeks after their last possible exposure and not allow interaction with other cats until that time. I'm sure the vet can tell you what age they recommend re-screening a young cat.

This is definitely something to discuss with your breeder.

Kittens born to mothers with FeLV will test positive, simply because the antibodies are in mum's milk.

It is recommended that kittens not even be tested until they're six months old, giving the antibodies the chance to clear their system. Unfortunately, WHATEVER age a cat is, the SNAP tests are unreliable, and 50% register a false positive. http://www.dr-addie.com/downloads/660_felv.pdf This brochure is produced by the UK's Cats Protection League, but there are labs in the US that can conduct the confirmatory tests. Unfortunately, the timing doesn't work with the anticipated delivery date of your kitty.

A SNAP (ELISA) test should never be relied upon as a definitive diagnosis. One of the IFA tests must be done (see the Cats Protection League Brochure. There are several confirmatory test options for FeLV).

Unfortunately, vaccinating your new kitty against FeLV to protect her from the just rescued kitty, if she does turn out to be infected, probably isn't an option as no FeLV vaccine is 100% effective.

Because of the problem you've got with the timing, your options are:

1) Find someone willing to adopt the kitty as an alone kitty, knowing she may have FeLV;
2) Figure out a way to keep FeLV kitty separate from your kitty. Does your daughter have her own room? Can kitty live there? If your daughter spends enough time at home to entertain her, and plenty of vertical space can be provided, and there's a window for entertainment, this might be an option;
3) TRY to find a sanctuary to take the little girl, even though she may not be FeLV positive. Most sanctuaries require a donation and have long wait lists (Tabby's Place in NJ has a 2-year wait list and requires something like $350);
4) Talk to the breeder about options. Maybe the breeder would be comfortable with the FeLV vaccine for the kitty you're adopting? :dk:

I can only give you my experience from 15 years ago, when far less was known.

I fostered three kittens who were SNAP tested at 8 weeks so they could go our for adoption. Nothing was known about the mother. One tested positive, the other two negative. They were re-tested four weeks later at which point two tested positive. They were re-tested repeatedly but this never changed. Based on more recent knowledge I believe the third kitten harbored the virus even though he tested negative repeatedly. One kitten died of anemia at 8 months. One cat, who I had tested every year because I was hoping she would fight off the virus, died of leukemia related cancer at 7 years. The cat who tested negative died of cancer at 9 years. The kitten who died at 8 months was always isolated but after he died the vet recommended I vaccinate all my cats (who had been street-hardened strays) and let them all mix. They were vaccinated annually. None caught the virus from the two FeLV cats and all died in their late teens and early twenties of age related illnesses.
 

Simka said:

The cat who tested negative died of cancer at 9 years.  

Click to expand...

:nod: It mentions in the Cats Protection League brochure that they can harbor the virus in their bone marrow. Sadly, a TCS member has a kitty that tested negative, but apparently that was the case: via bone marrow aspirate and PCR, they've determined her problem, and it's leukemia. I don't know how old Koko is, just that she's a senior kitty. (At first they thought her symptoms pointed to IBD). http://www.thecatsite.com/t/241609/koko-most-likely-has-ibd-a-new-journey-for-me But no, the FeLV was hiding in her bone marrow, and now many years later, she's actively fighting the disease.

My understanding is that while it was hiding in her bone marrow, she wasn't infectious. I'm not clear on whether she is now or not; or if it's just making her sick.

I read if the virus is found in the bone marrow, the cat will never test negative because that is in the later stages. So if you do the bone marrow test and it is positive, there is no need to retest. But I read that 10 years ago, so I can't remember if it is ELISA or IFA.

Something else I read was if you want to retest the cat, you have to wait eight weeks after the first test because it takes that long for a cat to develop immunity. After Wilbur's second test, his foster mom had to wait 60 days for the tiebreaker. I don't know why.

WhollyCat posted this VERY helpful link from Winn Feline Foundation in another thread: http://www.winnfelinehealth.org/pages/felv_web.pdf

It says the immunofluorescent antibody test (IFA) is the recommended confirmatory test, and because it does not test for antibodies, it can be done in kittens.

Here is the Winn Feline Foundation explanation of FeLV exposure (in the brochure linked to above):

When a cat is exposed to FeLV, there are four possible outcomes. In about 30% of cats, an effective immune response is produced and the infection is resisted. These cats then become naturally immune to FeLV infection for an unknown period of time. In about 40% of cats, the virus is successful and the cat eventually becomes persistently infected and excretes virus in its saliva. Another 30% of cats do not produce immunity but also do not become persistently infected immediately. In these cats, the virus hides in the bone marrow for a period of time. Eventually, these cats either overcome the virus or become persistently infected. Finally, some cats can develop latent or sequestered infection. This probably happens to about 5-10% of cats. These cats, whose virus is hiding in sites such as the bone marrow, will rarely be contagious and are unlikely to develop illness. They will not test positive on routine testing.

Click to expand...

EmilyMayWilcha said:

I read if the virus is found in the bone marrow, the cat will never test negative because that is in the later stages. So if you do the bone marrow test and it is positive, there is no need to retest. But I read that 10 years ago, so I can't remember if it is ELISA or IFA.

Something else I read was if you want to retest the cat, you have to wait eight weeks after the first test because it takes that long for a cat to develop immunity. After Wilbur's second test, his foster mom had to wait 60 days for the tiebreaker. I don't know why.

Click to expand...

I think you have it backwards. My understanding is if the virus is sequestered in the bone marrow, the cat will test negative UNLESS you go the expensive bone marrow biopsy route. And according to the Winn Feline information, even if FeLV is detected in the bone marrow, it doesn't mean the cat will ever become infected with the virus, and the cat is not infectious unless or until the cat somehow becomes sick from the latent/sequestered virus, and this happens only in 5-10% of the cases.

Momofmany just went through this with her kitty, Koko (link in an earlier post above). She was mysteriously ill as a senior kitty - but as a kitten, she was exposed to FeLV. She consistently negative for the disease. But as a senior, Koko's blood work indicated she was anemic and she had markers indicating inflammation. Amy (Momofmany) opted for the bone marrow aspirate, and they did find the FeLV virus via IFA or PCR testing (sorry, don't remember which). And Koko is now going through the classic FeLV progression, having avoided illness from it long enough to become a senior kitty. :heart3: :rub:

Wow Laurie, that is amazing for a cat to live so long after exposure. I always read if a kitten is exposed to the virus, it will not live very long unless it develops natural immunity.

Well, the Winn Feline Foundation outlines it pretty clearly. :dk: Some cats exposed to the virus will sequester it in their bone marrow. From the section of the Winn Feline report I quoted above,

Another 30% of cats do not produce immunity but also do not become persistently infected immediately. In these cats, the virus hides in the bone marrow for a period of time. Eventually, these cats either overcome the virus or become persistently infected. Finally, some cats can develop latent or sequestered infection. This probably happens to about 5-10% of cats. These cats, whose virus is hiding in sites such as the bone marrow, will rarely be contagious and are unlikely to develop illness. They will not test positive on routine testing.

Click to expand...

Given Koko sequestered the virus in her bone marrow, it seems she's a rare case where she eventually developed illness from it.