Feline leukemia virus (FeLV) is a retrovirus that infects cats. As
a retrovirus, the genetic information of FeLV is carried by RNA
instead of DNA. FeLV is usually transmitted between infected cats
when the transfer of saliva or nasal secretions is involved. If not
defeated by the animal's immune system, the virus can be lethal.
FeLV causes immunosuppression in pet cats, and there is also
evidence for existence of the virus in larger wild cat populations
also (e.g. Lynx, Cheetah, and Lion). Overwhelming epidemiologic
evidence suggests FeLV is not transmissible to either humans or
Note: Despite the its name, the disease is not a form of cancer.
The name stems from the fact that the first disease associated with
the virus was a form of leukemia, and by the time it was discovered
that the virus was the causal agent, the misleading name was
already being used by pet owners.