What is Feline Leukemia?

Feline leukemia virus (FeLV) is a disease that is highly contageous and weakens the immune system, increasing the risk of secondary infections. This virus infection is second only to trauma as the leading cause of death in cats, affecting all breeds. Males are more likely to contract the infection than females, and it is usually seen between the ages of one to six years old.

Feline leukemia is a disease that only affects cats — it cannot be transmitted to people, dogs, or other animals. FeLV is passed from one cat to another through saliva, blood, and to some extent, urine and feces. The virus does not live long outside the cat’s body — probably just a few hours. Grooming and fighting seem to be the most common ways for infection to spread. Kittens can contract the disease in utero or through an infected mother’s milk. The disease is often spread by apparently healthy cats, so even if a cat appears healthy, it may be be infected and able to transmit the virus.

Cats infected with FeLV may exhibit one or more of the following symptoms:

  • Pale gums
  • Yellow color in the mouth and whites of eyes
  • Enlarged lymph nodes
  • Bladder, skin, or upper respiratory infections
  • Weight loss and/or loss of appetite
  • Poor coat condition
  • Progressive weakness and lethargy
  • Fever
  • Diarrhea
  • Breathing difficulty
  • Reproductive problems like sterility in unspayed female cats

A simple blood test can be done to see if your cat has been infected with FeLV.  A positive result is not a death sentence, and your veterinarian can recommend treatment to help your cat.

New cats or kittens over eight weeks of age should be tested for the virus before being introduced to a multi-cat household. Most veterinarians counsel against introducing a new cat into a household with a FeLV-positive cat, because he or she may be at risk for contracting the infection – even with vaccination. In addition, the stress of a newcomer may adversely affect the FeLV-positive cat.

Keeping your cat indoors and away from infected cats is a sure way to prevent him from contracting FeLV.  A simple vaccination and annual examinations can help keep your cat safe and healthy.


Information taken from The American Association of Feline Practitioners, PetMD, and WebMD.