FeLV is more commonly known as Feline leukemia virus. Despite its name, it is not a form of cancer or leukemia, it is a retrovirus in the same family as FIV (feline immunodeficiency virus), and it is able to copy its own genetic material into infected cells, which is how it reproduces in an animal.
FeLV is known as a “friendly disease”, meaning that cats spread it to their friends. It transmits very easily between cats since the virus sheds in high quantities from saliva and nasal secretions. It can be passed from cat to cat as they groom each other, share food and water bowls, share litter boxes, and fighting amongst themselves, and it can pass from mother to kitten in the womb or to a nursing kitten by way of the mother’s milk. It can also be spread by urine and feces, though that is not as common. Even less commonly, it can be passed by way of flea bites, blood transfusions, or non-sterilized needles or surgical instruments.
The only way to diagnose FeLV is by way of a blood test. Your veterinarian can run a test in their clinic, and if the test comes up positive, a second sample is sent to the lab to confirm the diagnosis. Cats can test positive within a few weeks of exposure, and most cats who are positive will be so within 30 days. Younger cats are more susceptible to FeLV. Some adults are able to fight off the infection after exposure and will never develop the disease. Most veterinarians recommend retesting after 6 weeks if the test is questionable.
There is no way to diagnose FeLV from symptoms because there are no specific symptoms to watch for. Cats with FeLV generally have weaker immune systems and are more prone to common infections such as dental disease and upper respiratory infections. They can live normal lives, but their life spans are significantly shorter. Kittens with FeLV will generally live one to three years; adults can live a bit longer. FeLV does not cause death itself, but the cats develop other diseases due to the weakened immune system, such as feline infectious peritonitis (FIP), lymphoma, or bone marrow disease.
There is no treatment for FeLV. Preventative and supportive care is the most important part of caring for a cat with FeLV. Any illness or infection needs to be treated by a veterinarian as soon as it is noticed, and dental care is a high priority, since infections in the mouth and gums can pass through the bloodstream and cause more serious infections they can’t fight off. Raw foods and unpasteurized dairy products should be avoided because of the risk for foodborne bacterial and parasitic infections from such items.
Vaccinating any cat who goes outdoors or may be exposed to cats with FeLV with the FeLV vaccine can help prevent transmission of the disease. If your cat goes outside, or if you bring unvaccinated cats into your home (or cats that you are not familiar with their vaccine history), the vaccine can protect them from the virus.
FeLV cats must reside indoors, so they do not expose other cats to the virus, and can live in homes with FeLV negative cats as long as they live completely separately. They can never share food bowls, litter boxes, and can never come into contact with each other. They may have a shorter life span, and they do require more attentive preventative care, but they are worth it. FeLV cats are wonderful, amazing animals, and deserve the chance to live happy lives filled with love.