Feline Leukemia Virus

By: Paula Plummer, LVT, VTS (ECC, SAIM)

TVMA Member
College Station, TX

Published February 2018

What Is Feline Leukemia?

Feline leukemia is a common virus seen in the feline patient. This virus is seen worldwide in domestic cats. The virus is spread from cat to cat most commonly through casual contact via grooming, licking or bites in the saliva. A pregnant female cat can pass the virus to her kittens through the placenta or through her milk while nursing. The virus also can be spread indirectly when a cat comes in contact with an inanimate object such as food or water dishes or litter pans that have been contaminated with the virus. Other means of transmission include blood or nasal secretions.

Many cats that come into contact with the feline leukemia virus eliminate the virus and become immune. Those cats that do not develop immunity either become ill very quickly or develop a latent or silent infection. The virus spreads to the lymph nodes, bone marrow and blood. The virus then replicates and over time causes severe immune suppression and anemia, making the cat susceptible to certain types of cancer, liver disease and/or other viral, bacterial and fungal infections. Cats with latent infections do not immediately appear sick but can transmit the disease to other cats. Some cats with latent infections will become ill if stressed.

Clinical Signs

Due to the different types of infections, feline leukemia can become challenging to diagnose and treat. Because feline leukemia is an immune-depleting virus that makes cats more susceptible to secondary infections, the signs of feline leukemia can vary and be non-specific. Clinical signs include: weight loss, lethargy, loss of appetite, poor coat quality, enlarged lymph nodes, persistent fever, pale gums, recurring infections, diarrhea, seizures or other neurologic disorders and abortion.

Diagnostic Tests and Treatment Options

Most veterinarians diagnose feline leukemia with an in-house blood test. A second test may have to be sent off to a lab for confirmation. Other necessary diagnostic tests may include blood work, bone marrow aspiration and ocular (eye) examination. Once your cat has been diagnosed with feline leukemia, your veterinarian can discuss the specific type of infection affecting your cat.

There is no cure for feline leukemia virus. Treatment is typically supportive and may include fluid therapy, blood transfusions, treatment for secondary infections or diseases and nutritional support.

Preventative Measures

There is not a single preventative that is 100-percent effective in preventing feline leukemia. However, a combination of preventative measures can be taken to reduce the likelihood of your pet acquiring this virus. New cats and kittens should be tested before being brought home. Those who test negative and are at risk of contracting the virus should be properly vaccinated for feline leukemia. Risk factors include:

  • Cats that spend time outdoors
  • Cats that come into contact with other cats that have an unknown feline leukemia status (most likely at rescues, foster homes, etc.)
  • Cats that live with a feline leukemia-positive cat

Other preventatives measures to help reduce the likelihood of infection include:

  • Proper hygiene
  • Limiting the number of cats in and around your house
  • Reducing contact between your cat and other cats by keeping it indoors
  • Separating a feline leukemia-positive cat from other cats in the household

The Importance of Treatment

It is not recommended to leave feline leukemia untreated. Appropriate treatments to ensure pets live a longer, healthier life are available. If you feel your cat is at risk or may have contracted feline leukemia, please seek a veterinary health care team that can meet your family’s needs.

As always, consult your veterinarian if you have any questions or feel your cat is at risk for contracting feline leukemia.


Paula Plummer, LVT, VTS (ECC, SAIM), is a licensed veterinary technician who graduated from Murray State College in Tishomingo, Oklahoma. Ms. Plummer works in the Feline Internal Medicine Department at the Texas A&M University Veterinary Teaching Hospital in College Station, Texas.

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