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.
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).
ABCD cats & vets: GUIDELINE for Feline Leukaemia Virus Infection.

The test results showed that she had feline leukemia.When kittens are exposed to feline leukemia, their life expectancy is three years at most.Feline leukemi...
Diagnosis and Treatment. Feline leukemia is diagnosed via a blood test that detects a protein found in the virus.Although there is no treatment for feline leukemia, symptoms can be treated to keep your cat more comfortable.

Cats persistently infected with the gammaretrovirus feline leukemia virus (FeLV) are at risk to die within months to years from FeLV-associated disease, such as immunosuppression, anemia or lymphoma/leukemia. The integrase inhibitor raltegravir has been demonstrated to reduce...
Diagnosis and Treatment. Feline leukemia is diagnosed via a blood test that detects a protein found in the virus. Unfortunately, there is no cure for the disease.Although there is no treatment for feline leukemia, symptoms can be treated to keep your cat more comfortable.