I'm confused by feline leukemia testing

Since Gary tested positive and was PTS today, I've been doing some looking online about leukemia in cats. I've read where it is very contagious and can be spread by using the same water bowl and eating from the same food bowls. As I have mentioned several times, Gary would eat out of EVERY bowl there was. He would run the other cats off to different bowls every morning and evening. So needless to say, I am very concerned about the others that lived in the back with him (Juliet and Jose mostly). But then there is Higgins who lives in the back and in the front! Now all my cats have tested negative and have been vaccinated. Jose is the only one that isn't current. He was scheduled for boosters at the end of September, but because of the difficult situation of trying to catch Gary and not causing upset and trouble out back, I had to put it off. I'll get Jose to the vet as soon as I can and have him retested and vaccinated. Basically it seems though that cats can catch it even if they are vaccinated. So why give them the shot in the first place?

Then I was searching threads here and found this one. It has me completely confused! What is the benefit of testing if the results can't be trusted very much? Could Gary have had a false positive? If Jose or the others test negative, could that be wrong? What if one of them tests positive? This is so confusing. Then there is the whole thing about kittens. The vet wouldn't test Linus when they first took him, but he is going back tomorrow to be tested. What if it is positive but it could really be negative? If he tests positive, I'm sure they'll put him to sleep. Plus he's been around Cooter, who was tested and vaccinated before. This is just crazy. Does anyone have any answers or a way to help me make sense of this?

ETA: I changed all the water outside and washed all the food bowls that Gary had come in contact with. I have no idea where he used the bathroom. He's the first cat that has ever been here in over 10 years that tested positive for leukemia.

Oh dear, now I'm concerned about Paizly. I think I'll take her in to be tested again. She was tested several months ago when she was VERY young.
I'm going to see if I can take her in with Taggart next Friday.
Thanks for bringing this up, I would have never thought of it otherwise.

It is confusing, to be sure. After Buddy used a litter box that I had put in my garage for him and laid in the carrier that I used to take him to be tested, I completely emptied the litterbox and used bleach to clean it and the carrier, too. I've not read anything like that about testing and I guess I'll look into it tomorrow because my eyes are fading tonight. It's scary.

I know that you can have false positives, but you can't have a false negative. I was told that by a vet. If the antibodies are there, they will test + for either disease.

I don't know how many false positives there are, but I think many times they test positive when they have been exposed for a period of time, have been bitten (most adults testing positive are stray males) or are born with it. Most of the cats I know that have tested positive STAYED positive. I've only known of a few FIV+ cats that actually tested negative later on (they had basically contracted the antibodies from their mother, and the body fought it off).

Information about FeLV from Cornell University.

I am so sorry about Gary.

Like Jenn said, false positive can happen ( and DO often) but not false negative...

I have a possible Leukemia positive boy I am fostering right now. I just make sure that he does not come into contact with my cats ( he is in my bathroom) and I wash my hands after loving on him. I dont buy into it can be spread that easily. He is showing no signs or symptoms, no snot etc... So I cant worry about that.



FIV is no big deal IMO. They live fairly regular lives, and I am 100% supportive of FIV+ living with non FIV+ cats. It does work, and I hope one day, I can have a FIV of my own, but I cant at this moment.

Again so sorry about Gary.:(

I have an FIV+ boy living with me right now. HOneybun. He looks ancient, but that might just be because of the virus, but he's spunky as all get out and a total pain in the butt. He's about 14yrs old. He doesn't fight, doesn't bite (not a lot of teeth left... another FIV thing).

I had one foster, Piglet, who was adorable. He tested positive 2xs for his owner, then 1x when I took him in. He was retested about a year later when he was about 1 1/2 yrs old and he was negative. We retested him 2xs afterwards, and negative each consecutive time.

The previous owner did say his momma was pregnant, so it is possible that he fought it off and then became negative.


I've heard of that happening with AIDS babies as well.

Here's my concern. When I take Jose (or any of the others for that matter) in for his boosters and have him tested for leukemia, because that is what Gary tested positive for, could he show positive because he's had the vaccination before but really not have the disease?

And what if for some reason Linus tests positive? They have Cooter in their household already.

A cat doesn't test positive for FLV if he's had the shots.

FLV is contagious though saliva, but the virus only survives for a few hours exposed to air. Standard soap and water cleaning (a little bleach couldn't hurt) should make dishes and boxes safe for other cats.

I have four kittens (now 8 months old and huge!) who tested positive at 8 weeks and 6 months, but are asymptomatic. Tbey are isolated from the other cats.

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Originally Posted by smokey the elder

A cat doesn't test positive for FLV if he's had the shots.

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My understanding is that waaaay back when the FELV vax first came out they would show positive when they were simply vaccinated, but that is no longer the case.

No vaccine (human or animal) is 100% effective, but to be labled as a vaccine I believe they have to show a 90% or higher effectiveness against the disease when challenged with it. Despite vaccines not being 100% fullproof, they are the best protection available and are definately worth it.

Where I work cats with unknown histories (strays etc) are tested for FELV/FIV and then re-tested 6-8 weeks later to verify the results (regardless if negative or positive). The purpose of the retest on a negative or new cat is that it takes a while for the diseas to show up on a test after they are exposed. An immediate test wouldn't necessarily show if they've contracted the disease yet or not but would show if they've previously contracted the disease, hence the re-tests.

I've never heard of a false negative ever, we only see a very rare false positive, I mean like 1 every other year or two.

That is cofusing as I used to have My Found Cats take the nasal drops for FIP, until two breeders said that those drops made my Cats more likely to get FIP, not the other way around, something our Vet confirmed.:eek:
Why was I paying money to put The Found Cats at risk.:eek:

I went in to the vet's office today and asked them. They told me things very similiar to what Catlady711 said. The vet tech said that a false positive is VERY rare, although not impossible. She also said that while the vaccines aren't 100% guaranteed to prevent infection they are very helpful. They've never had a cat that was properly vaccinated contract leukemia and they've had several challenged. Those were her exact words, the same ones Catlady used. :) I've never had one of mine retested. They've never mentioned that as a possibility even. I asked about Jose because he is about 6 weeks late with his shots, and they weren't too concerned. If it had been closer to a year, then they would have been. I have an appointment to take him in first thing tomorrow for his vaccinations. I would have taken him on time, except there was no way for me to get him without risking scaring Gary away for days or weeks and getting Gary vaccinated and neutered was my priority. I hope all goes well with the crew. That's all I can do at this point. I kept waking up last night afraid of all the possibilities that could happen with leukemia running through my whole crew.

I can only post my experience.

About 14 years ago, I fostered three 3-week-old kittens, one of whom tested positive to FeLV at 7 weeks. Three weeks later, he was re-tested, still positive, his sister then tested positive and their brother was negative. The positive kittens were re-tested a few more times and always positive. The brother (Ted) tested negative all his life in spite of living with his sister. The first kitten to test positive (Roo) died at 10 months. The female (Seshat) lived for 7 years. After Roo died and she lost her companion, the vet told me that as long as my cats had already been vaccinated against FeLV, and their vaccinations stayed current, it was probable that they would not contract the virus since they were all adults (about 4-8 years old) and had been strays. This proved to be perfectly correct. Seshat lived with the other cats, sharing everything, and none of the 8 cats she lived with ever contracted FeLV. They died of renal failure, heart disease, etc. in their late teens, and Ginger is now in her 23rd year. In fact, none received their booster shot after the first 4 years because some became ill afterwards, and there was an injection site sarcoma scare.

Last year, I fostered nine kittens that came from a very poor home and were in pretty bad shape when they came to me. One had tested positive to FeLV, the shelter didn't test the others. After four months, they were all tested and all were negative. However, their bad beginnings did do harm to their immune systems since three of them contracted FIP while at the adoption center.

Isn't it FIV that can show positive when a cat has been vaccinated against it?

I'm with Jenn and others on FIV and sharing. It doesn't even occur to me to be concerned about my big FIV+ boys mixing with my own and foster non-FIV cats. Calling it feline AIDS makes it sound far more scary and serious than it really is, and is a great dis-service to FIV+ cats who are longing for their own homes.

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Originally Posted by Lizzie

Isn't it FIV that can show positive when a cat has been vaccinated against it?

Calling it feline AIDS makes it sound far more scary and serious than it really is, and is a great dis-service to FIV+ cats who are longing for their own homes.

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Yes it is possible the vaccine for FIV can show as a positive on a test result. Not sure of the stats on how often this happens though.


We call it feline AIDS because basically it is.

http://www.winnfelinehealth.org/health/FeLV-FIV.html
FIV belongs to the same family of viruses as HIV (human immunodeficiency virus) and immunodeficiency viruses in other species. This family of viruses (Lentiviruses) is known for being species-specific, for life-long infection, and for slowly progressive diseases. FIV is not transmissible from cats to people, and HIV is not transmissible to from people to cats.

The thing with FIV is that if they are aggressive, I would not mix them with my other cats. Honeybun is old and crotchety, and grumpy, but not aggressive. He has hardly any teeth, so am I worried about him biting someone else and passing it? No. Zach may be a bully, but he's also NOT a biter. Every situation is different, and every cat's personality has to be considered.

I did have one cat that i fostered for about a week or so that was FIV+ before I had Honeybun. He was super aggressive, and I eventually gave him back to his regular foster home. He would corner my own guys, and would snarl and hiss and just be really nasty. That I would not tolerate. I won't jeopardize my healthy cats just to take in a FIV+ one.

If they are not aggressive, and mine are not aggressive, then we're good to go. ;)

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Originally Posted by Catlady711

FIV is not transmissible from cats to people, and HIV is not transmissible to from people to cats.

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My one doctor was worried about me having an FIV+ cat in my home. That man watched Outbreak one too many times, lol.

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Originally Posted by jenn_librarian

My one doctor was worried about me having an FIV+ cat in my home. That man watched Outbreak one too many times, lol.

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ROFL that movie STILL freaks me out no matter how many times I've seen it.

I suppose a human dr. wouldn't understand the differeneces in species specifics for animals if all he knows is the disease is similar to (in cats at least) as the human HIV is. Kinda like our vets don't know alot about some of the human aspects of some things, other than there are some things people can get from pets (FIV isn't one of them).

We still occasionally get a client showing us their rashes/bites etc and asking us if it's flea bites/mange/ringworm/staph/fill in the blank. We keep telling them that we are not qualified to diagnose humans they should go to their own doctor. :rolleyes: I've often secretly wondered if they bring their pet to their own dr's office and ask them if it has ______(fill in the blank). LOL

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Originally Posted by jenn_librarian

I know that you can have false positives, but you can't have a false negative. I was told that by a vet. If the antibodies are there, they will test + for either disease.

I don't know how many false positives there are, but I think many times they test positive when they have been exposed for a period of time, have been bitten (most adults testing positive are stray males) or are born with it. Most of the cats I know that have tested positive STAYED positive. I've only known of a few FIV+ cats that actually tested negative later on (they had basically contracted the antibodies from their mother, and the body fought it off).

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Both my vets wouldnt test for Leukemia before the cat was 6 months old. They told me you can get false negatives.

Let me give you an overview of how it was presented to me in my animal diseases class.

A cat who is exposed to FeLV can test positive. That doesn't mean that cat will contract the disease. There are three possibilities.

First, many cats are exposed, fight it off, and later test negative. So there is a period of a month or two where they will test positive because the antibodies are present in their system.

This is why none of the vets I worked for considered a positive FeLV test to be a death sentence; they always re-tested three months later. The cats who later test negative have developed immunity due to their exposure to the virus. It is very common for young outdoor kittens to be exposed and test positive but later (and forever after) test negative.

Second, some cats are exposed, never become sick, but always have antibodies present when tested. These cats can be contagious.

Third, obviously, some cats do become sick.

To add a little to my reply, FeLV is spread through long-term contact. It is not highly contagious.

If you had a kitten who tested positive for FeLV, I would say DO NOT LET THEM EUTHANIZE!! It SHOULD NOT BE AN AUTOMATIC DEATH SENTENCE!! Wait three months and re-test.

Honestly, when I first read that they euthanized Gary automatically because of an FeLV test, I was pretty horrified. It's such a poorly understood disease, and cats beat it frequently enough that it should in no way mean automatic death. I've worked for three different clinics, one of them cat-only, and the wait-retest strategy was universal between the three of them.

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Originally Posted by CathyBogart

Let me give you an overview of how it was presented to me in my animal diseases class.

A cat who is exposed to FeLV can test positive. That doesn't mean that cat will contract the disease. There are three possibilities.

First, many cats are exposed, fight it off, and later test negative. So there is a period of a month or two where they will test positive because the antibodies are present in their system.

This is why none of the vets I worked for considered a positive FeLV test to be a death sentence; they always re-tested three months later. The cats who later test negative have developed immunity due to their exposure to the virus. It is very common for young outdoor kittens to be exposed and test positive but later (and forever after) test negative.

Second, some cats are exposed, never become sick, but always have antibodies present when tested. These cats can be contagious.

Third, obviously, some cats do become sick.

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I remember in 2003 my mom took one of the strays I was feeding in, before we did anything we brought her to the animal hospital. I remember the doctors exact words were "If she tests positive for Leuk. she doesnt leave here" My mom and I looked at eachother and when the vet left the room we were like, 'To hell she isnt'

Sounds like no one knows what their talking about.