“Do you know of any shelters or sanctuaries that would take a kitten who has feline leukemia? She’s been living in my bathroom for the last two weeks after being put out of his regular home by my neighbors. I’ve been keeping her in my bathroom because I have other cats. Do you have any suggestions to help me?”The most important thing to remember about a cat or kitten that tests positive for Felv is to make absolutely certain the test was accurate before taking action.
It used to be that feline leukemia (Felv) positive cats were routinely euthanized to prevent the spread of the disease to other cats. Over the years, as we’ve learned more about the disease and its rate of contagion, the policy has changed considerably. Today, although testing positive often results in euthanasia at animal control based shelters – it’s more because it’s a litmus test of adoptability than it is warranted by the disease. If you search the internet for information on Felv you’ll find a mishmash of conflicting data. Fortunately in 2008, the American Association of Feline Practitioners issued updated guidelines on Felv that provide a little assistance in determining what to do if you have a Felv+ cat. As good as their guidelines are, it’s important to disclose their research was funded by Idexx – the company that manufactures the common snap tests used by veterinarians to detect Felv. Here are some of the key points from their study:
1. What is Felv?
Felv is a retrovirus . During its early stages a cat is likely to not exhibit any symptoms. After weeks or months or years the cat may start having recurrent intermittent illness. Signs can include loss of appetite, weight loss, poor coat, enlarged lymph nodes, fever, pale or inflamed gums, URI, skin or bladder infections, and persistent diarrhea.
2. How common is Felv?
In the overall cat population (living indoors or outdoors) less than 2% of healthy cats have Felv. This rate is down considerably from what it was 20 years ago – possibly due to the availability of vaccines or possibly because of better record-keeping and testing established once the disease was identified.
3. Who is most at risk for Felv?
Kittens under 4 months of age are in the highest risk group. The most common transmission is from infected moms to their kittens and as cats develop more effective immune systems their resistance to the Felv virus increases. One study cited in the AAFP 2008 report injected the virus into a group of newborn kittens (less than 2 months of age) and virtually all of them developed a progressive Felv infection. In another group of kittens over 4 months old, only 15% contracted the disease once they were infected with it. This does not mean that cats over 4 months of age can’t contract Felv, it simply means that they are much more likely to shed the virus if they do come in contact with it. The virus is highly fragile and lives only a short time outside the body of an infected cat.
Vaccinating kittens under 4 months of age for Felv is recommended because they are at a much higher-risk of contracting the virus than older cats are.
4. Who does AAFP recommend be tested for Felv?
a. Pet cats or kittens before they are first brought into a home. It’s important to determine if the cat is positive to prevent inadvertent transmission to other resident cats or – even if the cat will live alone to prepare a treatment plan if the cat is positive.
b. Cats that will have ongoing exposure to untested or Felv+ cats. It’s recommended that to minimize their potential to contract Felv that they be vaccinated annually – and, before the first vaccination they should be tested to confirm they are Felv-negative.
c. Cats that have recently been bitten by a cat that is (or could be) viral positive or cats
d. Cats that have become ill even if they have previously tested negative on a Felv test.
5. Should outdoor only cats (aka feral cats) be tested for Felv?
Althought the AAFP broadly recommends testing all cats, they exclude feral cats from their recommendation. The prevalence of infection is similar to outdoor pet cats so feral cats do not present an increased threat to pets given outdoor access. They do recommend neutering outdoor cats because this greatly reduces the two common modes of transmissions: queen to kittens and bite wounds caused by fighting among intact males.
6. How is Felv diagnosed?
The Idexx “Snap Test” is typically done at a veterinary clinic when a client brings a new pet cat in for their first examination. The same test is often performed by rescues and animal shelters when they intake a new cat for adoption.
If the test is negative, the cat is generally considered free of the Felv virus. But, if the cat’s last potential exposure to Felv was less than 28 days earlier, to be absolutely certain the cat is negative, another Snap Test is recommended after a 28-day incubation period is done – a time when the cat cannot come in contact with untested or Felv-positive cats. This protects against infections that were too immature during the first test to be detected. It will not protect against the potential that cat has the virus but is in a dormant state – which is also not detected by the Snap Test – and is why an ill cat that tested negative needs to be retested. So although a negative result is good, it’s not foolproof.
The real drama begins when the initial vet clinic or shelter test shows a positive result. Does this mean that the cat is infected with the Felv virus? Maybe, but since the impact on a cat is so major –if the cat is visibly healthy – the first positive test should be viewed with caution.
When a positive test result happens, Idexx Laboratories advises veterinarians to immediately retest the cat using an IFA test. If that is positive, then consider the cat infected and begin an appropriate management plan for the cat.
But, if the IFA test is negative, the results are inconclusive. The infection is either in an early stage or the original Snap (ELISA) test was incorrect. To determine which, Idexx recommends waiting 28 days and then re-administering both the Snap and the IFA test. If the second group of tests are both positive, you can assume the cat is Felv positive. And, if both tests are negative then you can assume the cat does not have the virus. But what do you do if you have a negative on one test and a positive on the other even after retesting a second time? According to Idexx, if the Snap test is the positive test you should manage the cat as if the virus is present but retest the cat every 6 months using both of their tests. If, on the other hand, the IFA test is positive but the Snap test is negative, then one of the results is wrong and both tests should be repeated.
Very early in our spay/neuter programs, we routinely tested for Felv . We found the incidence in our program was very low – as is confirmed by the 2008 AAFP report. And, we determined that the money spent on viral testing could better be applied to increasing the number of cats we fixed – to stem the most common means of transmission – mothers to kittens or fighting intact male cats.
Felv testing opens a Pandora ’s Box. Testing is far from perfect. Although you’re reasonably safe in assuming a negative result is negative both AAFP and Idexx recommend testing again 28 days after the cat is removed from an uncontrolled environment to confirm the virus wasn’t incubating. And they also recommend testing again if the cat later becomes ill. It’s even more a nightmare when you get a positive result and then have to go through a series of retesting to confirm the positive test was in fact real.
That being said, testing a new cat you’re bringing into your home to live with existing pet cats is a reasonable assurance that you are not inadvertently exposing them to Felv. Just remember that if you get a positive test result, it’s only an indicator the virus may be present but isn’t in itself a reason to not adopt a cat – or to euthanize one. Felv positive cats can live meaningful lives up to the point they become ill – weeks, months or years later -- with a disease causing untreatable pain with no expectation of recovery.
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