Why Feline Leukemia is so Dangerous
Recently, we have seen some very sad cases of cats diagnosed with Feline Leukemia Virus (FeLV).
FeLV is a common infectious disease in cats. It is most often found where there are a lot of cats, such as in a multi-cat household or where feral cats live in a free-roaming community. It is easily transmitted and it may take a while for symptoms to develop. Unfortunately, there is no cure for FeLV. If your cat tests positive and has a progressive infection, he will remain infected for the rest of his life. Young cats and kittens, especially those under three years of age, are the most susceptible to FeLV.
Most shelters and rescue organizations do NOT vaccinate for FeLV because it is an optional vaccine and, quite frankly, they may not be able to allocate funds for it. You may adopt a cat thinking “it has all its shots”, but please make sure your cats are protected against FeLV.
When cats are brought in for a post-adoption exam, I will discuss FeLV and recommend vaccination. Many people, however, elect not to vaccinate for FeLV because their cat will be strictly indoors and unlikely to be exposed. Unlikely, but not guaranteed.
One three year old cat escaped and went missing for 5 days. He returned with no apparent ill effects until, six months later, he developed a high fever. He was diagnosed with FeLV and his family was crushed. Their other unvaccinated indoor-only cats were exposed, so they were quickly tested and vaccinated. Everyone, including the FeLV cat, is doing okay for now. But, eventually, FeLV-associated diseases can occur and can include: anemia lymphoma, chronic respiratory infections, chronic gingivitis and stomatitis (inflammation of the gums and mouth). Positive FeLV kittens usually live only two years before developing life-threatening illnesses.
The test for FeLV is a quick blood test. Most shelters will test cats before they adopt them out. If a cat tests positive on the in-house test, blood is sent to a reference laboratory for a more definitive test. If both tests are positive, the cat has active FeLV. If the first test is positive and the lab test is negative, we wait a few months and test again. Cats can clear the virus if their immune systems are strong. The difficult cases are the cats who test positive on one test and negative on the other for an extended period. We must assume they are infected, but the virus can remain latent for a long time. Zach, at our clinic, has remained positive/negative for over four years. But we assume he is positive, so he lives in his own apartment away from other cats.
Don’t worry, he gets a lot of love from the humans and has windows so he can “play” with UFO, who teases him unmercifully. Zack has shown no symptoms of the FeLV so he is periodically tested to see if he has cleared the virus
FeLV is a very sad and frustrating disease. At the clinic, we and our clients have suffered the heartbreak of discovering that a loved cat is positive for the disease. This is why I recommend vaccinating ALL cats against FeLV. Regular vaccination is especially important for kittens and young cats, whether they are indoor-only or go outside. The first FeLV vaccines are given in two shots administered three weeks apart. The vaccine is then boosted annually. As cats age, they become less susceptible to the disease. I do not vaccinate indoor-only cats once they reach seven years of age. Or, I recommend vaccinating every other year instead of annually. I do recommend keeping outdoor cats vaccinated until they are senior, above the age of 12.
In my opinion, there is only one safe FeLV vaccine: Merial’s PureVax. It is a yearly vaccine which does not contain a preservative that causes horrible cancers in cats. There are three-year vaccines available, but I do not recommend them because they carry the risk of cancer.
Why take the chance of your cat getting FeLV? Feline Leukemia cannot be cured.