by Amanda L. Maus DVM
Feline leukemia virus (FeLV) is an uncommon but deadly disease that can affect cats. It is a retrovirus similar to FIV and HIV, but it is not spread between cats in the same way as FIV. FeLV is spread by casual contact of infected bodily fluids such as saliva, blood, urine, feces, nasal discharge, and milk. For this reason, transmission is possible through shared litter boxes, food dishes, communal grooming behavior, cat fights, and from mother cat (queen) to kitten. Luckily some cats exposed to the virus have an immune system capable of completely eliminating the viral infection within 6 weeks of exposure.
Cats that cannot defeat the virus before it enters the bone marrow will have the disease for life. These cats can develop several different types of outcomes. The two most common consequences are severe anemia or lymphoma cancer. Other FeLV infections may result in a suppressed immune system, secondary infections, inflammatory conditions, neurologic diseases, and/or intestinal diseases. For this reason, the symptoms of an infected cat can be very different in each case.
When you adopt any new cat or kitten, it is very important to have them tested for FeLV. This is especially important if they will be living with other cats since the disease is so easily spread. Most cats will be positive on a FeLV test within a month after initial infection but it may take up to 3 months for a positive test result. Asymptomatic cats that can be kept quarantined may be retested again to see if they will eliminate the virus.
There is no cure for this disease but there are treatments available for the different diseases and symptoms cause by FeLV. Most infected cats only survive a few years after diagnosis.
For cats at a high risk of being exposed to FeLV positive cats, there is a vaccine available. Common household disinfectants can kill the virus.