Feline leukemia virus is a retrovirus that infects cats. FeLV can be transmitted from infected cats when the transfer of saliva or nasal secretions is involved. If the animal's immune system fails to neutralize the virus, it may become severely weakened by it, potentially leading to lethal disease.
Diagnosing Feline Leukemia Virus. Your veterinarian can diagnose the disease by conducting a simple blood test called an ELISA, which identifies FeLV proteins in the blood. This test is highly sensitive and can identify cats with very early infections.
Feline leukemia virus (FeLV) is one of the most common infectious causes of disease of cats globally. Infection with FeLV can cause a variety of clinical signs, impacting a cat's longevity and quality of life.

Feline leukemia virus infection. In: Feline Husbandry. Disease and management in the multiple-cat environments. American Veterinary Publications, Inc., Goleta, CA, USA, 1991, pp210-228.
Feline leukemia virus (FeLV) is one of the most common and important infectious diseases in cats, affecting between 2-3% of all cats in the United States and Canada. Infection rates are significantly higher (up to 30%) in cats that are ill or otherwise at high risk (see below).

How Veterinarians Diagnose Feline Leukemia Virus (FeLV). Feline leukemia is usually diagnosed by a test that requires a small amount of blood, called an ELISA test. This test is quick and routinely done in veterinary clinics.
External Websites. Feline leukemia Feline leukemia virus (FeLV), electron micrograph. (more).feline leukemia, viral disease of cats, one of the most serious diseases affecting domestic cats and a few other Felidae.
Abstract. Practical relevance Feline leukaemia virus (FeLV) is a retrovirus of domestic cats worldwide. Cats lacking strong FeLV-specific immunity and undergoing progressive infection commonly develop fatal FeLV-associated disease.