Feline Leukemia Virus (FeLV)

Feline leukemia virus (FeLV) is a common infectious disease that spreads from cat to cat through the exchange of body fluids during casual contact or fighting.

FeLV infections begin with an acute viremia followed by an asymptomatic phase. The final stage takes one of two paths:

  • A progressive infection that is not contained; the virus propagates in the bone marrow and the cat develops FeLV-associated disease.
  • A Regressive infection where the cat remains infected, but reverts to an aviremic state. This cat is unlikely to develop FeLV-associated disease. 

Identifying infected cats helps limit the spread of FeLV and improves treatment options for FeLV-positive cats.
Feline Heartworm
Diagnosis
Treatment

Antigen ELISA is the first line in FeLV testing. It detects FeLV antigen in the blood. As infection progresses, the bone marrow can become involved. A follow-on IFA test detects the antigen in white blood cells. A definitive diagnosis is made when the both tests are positive.

All cats—FeLV diagnostic algorithm
FeLV Diagnostic Algorithms

View/print the Diagnosing and Managing Patients with FIV/FeLV (PDF) guide.