What is Feline Leukemia

Feline leukemia is a cancerous disease caused by feline leukemia virus (FeLV). FeLV causes diseases other than leukemia including other cancers and immunodeficiency.

Cats may not start to show signs of disease for months or years after being infected with FeLV. Infection with FeLV is a major cause of illness and death in domestic cats.

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. Retroviruses are made up of RNA. In the host, the RNA is transcribed into DNA and incorporated into the DNA of the host's cells.

Retroviruses are fragile, being easily inactivated by ultraviolet light, heat, detergents, and drying. Retroviruses are widespread in nature, and have occurred for many millions of years.

It is estimated that 1-2% of otherwise healthy cats are infected with FeLV. Males are more commonly infected than females, and cats with access to the outdoors are more at risk of becoming infected than indoor cats. Kittens are much more susceptible to FeLV infection than adult cats.