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.
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.

Prevention of Feline Leukemia. Cats over four months of age are significantly more resistant to infection. Adult, indoor cats are among the least susceptible to infection and generally should not be vaccinated regularly for the disease.
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).

As we can see from the illustration, Feline Leukemia In Cats Under 18 Months has many fascinating aspects to explore.
Causes of Feline Leukemia Virus (FeLV). FeLV in cats is spread through saliva. It is spread most commonly from those exposed to one another for longer periods of time through mutual grooming, mating, or shared food/water/litter boxes.