FELV is an abbreviation for Feline Leukemia Virus. This is a retrovirus that infects cats only. No dogs or humans have shown infection with this virus. FIV stands for Feline Immunodeficiency Virus which is a lentivirus that infects cats as well. Both viruses are transmitted through saliva and biting seems to have the highest rate of potential infection to other cats. If cats are outdoors or indoor-outdoor there is a higher risk of exposure related to the fighting amongst cats for territory and during the mating season. We have concern that even when in close association with a positive FELV cat there could be exposure through saliva when grooming each other and even nasal excretions with sneezing. Caution should be exercised with food dishes and litter boxes.
It is always recommended that a cat and or kitten be tested for both of these viruses prior to introduction to any other cats in your home. It Is important to protect all cats that are in your home when considering an addition to your household. The tricky part is that most research indicates a new cat should be tested 30 days after its last exposure to other cats to make certain that the virus is not incubating within your new cat. Most shelters check for FELV and some for FIV. It is important to ask questions at the time of adoption so you know what has already been done. Ask about the quarantine and if the test was done 30 days after it’s last exposure to other cats with unknown histories.
FIV has been labeled the Feline AIDS like infection for cats. It is not contagious to humans. Cats can live perfectly normal lives with the FIV virus and infect other cats in the area over the years. Worldwide about 2.5-4.4% of cats are infected with FIV. This virus is spread through bite wounds so living casually amongst other cats that do not fight can prevent the spread of the virus. It has been shown that some cats immune system will challenge the virus and the cat will get lifetime immunity. Other cats may always be a carrier affecting other cats around them when fighting or breeding, and then sadly enough some cats end up with a compromised immune system and become extremely ill and can die from the virus. Since the immune system is affected the clinical signs can be varied so blood tests are the only way to diagnose this infection.
FELV is species specific for cats but evidence points to potential infections within the larger wild cat populations, such as lions. Nationwide, we see an infection rate of 2-3%. A newborn kitten can be born with the infection if the female is positive. Some cats can fight off the infection and will show antibodies against it indicating prior exposure. Positive cats be carriers for their lifetime and die of natural causes or they can become extremely ill and eventually die from this infection. This virus affects the immune system as well and so the clinical signs can be numerous. A blood test is the only way to know if your cat has FELV.
Testing for both FIV and FELV can be done within most veterinary facilities. There are also different tests that can be done at professional laboratories if there are any concerns or questions about the accuracy of the first test. Any cat that is going to be introduced to your current cat population should be tested prior to allowing the cats to spend time getting to know one other. If you cannot wait the 30 day period before introduction, then have the cat tested on day 1 and then retest them 60 days later to make certain they are not carriers of the viruses. A positive test does not mean your cat is dying. It indicates your cat has been exposed. It says your cat can be a potential carrier for the virus. It means you need to offer the best preventive care to reduce stress for this cat. It is important to seek veterinary care if your cat becomes ill. It is necessary to know the risks to other cats in your household or outside.
Vaccinations are available to protect cats against FELV and FIV but neither are 100% effective. The FELV vaccine has reduced the percentage of positive cases since it was introduced over 30 years ago and will not cause a false positive on the blood tests. The FIV vaccine can generate antibodies after vaccination which then make it difficult to determine which cats are positive for the virus and which cats have been vaccinated. If you vaccinate your cat against FIV make certain to tell your veterinarian. These vaccines are of little use if your cat never goes outside or is never exposed to other cats that have these viruses. These vaccines are administered when the risk is present for potential exposure to other cats that carry the viruses. THE BEST WAY TO PREVENT INFECTION IS TO AVOID EXPOSURE TO CATS AND KITTENS OF UNKNOWN STATUS OF FELV OR FIV.
Treatment of cats diagnosed with either of these viruses is symptomatic. There are no proven formulas to remove this infection so if the cat is not eating you must find ways to feed it. If the cat has seizures you must seek medications to stop the seizures. If the cat has cancer you must seek the advice of an oncologist. If the cat has reoccurring upper respiratory infections antibiotics may always be needed. Keeping your positive cat healthy and happy with minimal stress may allow them to live a long life free of clinical disease. Yet, as with all viruses that affect the immune system, in spite of all of your efforts your cat can become clinically ill at any time. Many people request vaccinations for their indoor-outdoor cat(s) against FELV and do not do the test. I let them know that is their choice, but to always remember if their cat gets sick and conservative treatments are not turning the illness around, you must let your veterinarian run the diagnostic tests for FELV and FIV. These infections are more common than we would like to believe and without doing the tests you may never know the status of your cat.
In closing I want to thank all those people with big hearts that take in stray cats and kittens. Most cats seem to find their owners more than the owners find them. I applaud those efforts but also want to make certain you are aware of the risks to your current household population and please quarantine these strays until they can be seen by your veterinarian to avoid risks not only for FELV and FIV but so many other contagious conditions such as internal and external parasites, fungal infections, upper respiratory infections, etc. A new cat or kitten can be the demise of a current cat if you are not cautious.