FeLV is a type of virus called a retrovirus. That puts it in the same family as feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV, the virus that causes AIDS). Retroviruses are species-specific. This means a feline retrovirus will only infect cats; a human retrovirus will only infect humans. Additionally, this virus is very unstable and dies quickly outside of the animal.
This virus is spread in the cat population by contact with secretions from infected cats. It takes a large amount of virus and a prolonged exposure to infect a cat.
Saliva of infected cats usually contains large amounts of FeLV. Therefore, the most common mode of transmission is through nose-to-nose contact. Bites are also a very efficient way of transmitting the virus. Other ways that a cat can transmit FeLV are through grooming, licking, and sharing dishes and litter pans.
The prognosis for cats infected with FeLV depends on the immune status of the cat, the cat’s level of exposure to the virus, and its vaccination history. Disease caused by FeLV is very serious, and it is estimated that fewer than 20 percent of persistently infected cats will survive more than three years.
No known treatment exists for FeLV. Some treatments that have been investigated include antiviral drugs, such as AZT, which has many side effects. Other treatment protocols include drugs that stimulate the immune system, such as ImmunoRegulin and interferon.
Specific cancers associated with FeLV have their own treatment protocols. Other problems created by the virus, such as bacterial infections, are treated symptomatically.