Feline Leukemia Virus is an autoimmune virus which can be transmitted between cats by mucosal contact. Sharing of food, water, litter boxes or grooming can be vectors of transmission as can bites. The virus can also be transmitted in utero from infected queens to their unborn kittens. Because there is no known cure, prevention is stressed by veterinarians. Eliminating contact with unknown or stray cats is always recommended. A preventative vaccine was developed and is generally advocated for all cats. While the vaccine is effective most of the time, it is estimated that approximately 30% of cats which are immunized will still develop Feline Leukemia if they are exposed to the virus. However, approximately 30% of all cats have developed a natural immunity and do not develop Feline Leukemia even if they are exposed to the virus without immunization.

There are currently two assays used to determine the presence of Feline Leukemia Virus. ELISA (enzyme-linked immunosorbent assay) or IFA (indirect immunofluorescent antibody assay). ELISA tests are usually the first tests given and results can be determined very quickly in veterinary offices. IFA tests usually must be sent to diagnostic laboratories, but are conclusive at determining the stage and progression of the illness.

Treatment options are limited. Although interferon has been used as a treatment technique (primarily in Europe), there are no conclusive studies which show it to be effective at suppressing or controlling the virus. The USDA approved a new treatment for the virus in 2006. IMULAN BioTherapeutics, LLC developed their Lymphocyte T-Cell Immune (LTCI) Modulator and licensed production to T-Cyte Therapeutics, Inc.

Other treatments which have been used with varying limited degrees of success include the use of high dose steroids (primarily prednisolone which is eventually tapered to maintenance doses once a flare has been controlled) and the use of high doses of Vitamin B. Steroids suppress the immune system to help defeat the autoimmune nature of the virus, but can have long-term negative effects, including but not limited to leaving the cat open to infections or other illnesses.