What You Need to Know About Feline Leukemia Virus Infection (FeLV) in Cats

Sad lonely cat. What you need to know about Feline Leukemia Virus (FeLV).

Reviewed by Dr. Cynthia Sweet, Badger Veterinary Hospital-Beloit

Feline leukemia virus (FeLV) affects about 2-3% of cats in the U.S. And while that seems like a small number, FeLV is one of the most common infectious diseases in cats.

Thanks to vaccine development and more accurate testing, the prevalence of FeLV has decreased significantly. However, it’s a serious disease that all cat owners should understand.

Here’s what you need to know about feline leukemia virus (FeLV).

What Is Feline Leukemia Virus (FeLV)?

First and foremost, feline leukemia virus is not cancer of the blood or bone marrow like leukemia is for humans. It’s a virus that impairs a cat’s immune system. And while it’s not cancer itself, it can cause certain types of cancer and is the most common cause of cancer in cats.

How Do Cats Become Infected?

The most common way for cats to get infected with feline leukemia virus is cat to cat transmission through close contact, grooming, sharing dishes or litter pans, and bites. It can also be transmitted to a kitten at birth or through the mother’s milk.

Kittens are more susceptible to the virus. Male cats and cats with outdoor access are more susceptible to the virus as well. FeLV only survives a few hours at most outside the body, so overcrowded environments and unsanitary conditions also increase the risk of infection.

What Are the Symptoms of Feline Leukemia Virus?

Some of the more common symptoms or clinical features of feline leukemia virus include:

  • Lethargy
  • Loss of appetite
  • Progressive weight loss
  • Persistent diarrhea
  • Enlarged lymph nodes
  • Infections, such as of the skin, urinary bladder, and respiratory tract
  • Poor coat condition
  • Persistent fever
  • Wobbly, uncoordinated movement
  • Seizures, behavior changes, or other neurological disorders
  • A variety of eye conditions
  • Inflammation or infection of the gums and/or mouth tissues
  • Lymphoma (the most common FeLV-associated cancer)
  • Leukemi
  • Fibrosarcomas (cancer that develops from fibrous tissue)
  • Cytopenias (low blood cell counts), with anemia being most common

How Do We Diagnose and Treat FeLV?

Diagnosis of FeLV infection is based on a cat’s medical history, clinical signs, and test results. Blood work will identify the presence of FeLV.

Unfortunately, there is no cure for feline leukemia virus at this time. Treatment is focused on the problems associated with the disease, like antibiotics for infections or blood transfusions for severe anemia. Diarrhea, kidney disease, or chronic muscle loss may require a special diet.

Infections are an ongoing concern due to a weakened immune system. More than 50% of FeLV-infected cats succumb to related diseases within two to three years after infection. Cats should be monitored for signs of infection as well as any signs of abnormality. Any changes should be discussed with your veterinarian immediately.

FeLV-infected cats should be kept indoors and be separated from other healthy cats to prevent transmission. Good nutrition and regular vet checkups are also crucial for maintaining health and quality of life.

How Can Feline Leukemia Be Prevented?

There is a vaccine for FeLV. However, it will not protect 100% of vaccinated cats and is not considered a core vaccine. Talk with your veterinarian about your cat’s risk of exposure and the advantages and disadvantages of vaccination.

The only sure way to protect your cat from feline leukemia is preventing exposure to FeLV-infected cats.

  • Keep your cat indoors.
  • If you allow outdoor access, supervise your cat or keep them in a secure enclosure to prevent them from wandering off.
  • Before adding a cat to your home, test him/her for FeLV.

If you have any questions about your cat’s risk of exposure to feline leukemia virus or concerns about your cat’s current state of health, contact us to schedule an appointment.