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Let’s Review: Facts About Feline Leukemia Virus

Let’s Review: Facts About Feline Leukemia Virus

Is Your Cat at Risk for Feline Leukemia Virus (FeLV)?

Let’s review the facts about FeLV, including how it’s spread, diagnosed and prevented. It’s important to keep FeLV-positive cats isolated from other cats because some infected cats can harbor the virus for a long time and may become carriers that spread the disease to other cats, even though they appear healthy.

Causes of FeLV

FeLV is caused by a virus, which can result in a weakened immune system (immunosuppression) or even cancer (leukemia) in cats. FeLV is usually transmitted in a cat’s saliva through close contact such as grooming, fighting, playing or sharing water and food bowls. In some cases it may also be transmitted through urine or feces, so cats that share a litter box with an infected cat may be susceptible. It can also be transmitted via blood or from a mother cat to her kittens.

Prevalence of FeLV

FeLV is more common than you might think. According to Banfield’s State of Pet Health™ (SOPH) Report, in 2014 about one in every 200 cats had FeLV infection.1 It is more commonly seen in young cats, as the SOPH report shows that in 2014 cats under 3 years of age were almost twice as likely as mature adult cats (3 to 10 years of age) to have FeLV infection.1 In addition, cats under 3 years of age were almost three times as likely to have the infection compared to geriatric cats (10+ years old).1

A vaccine exists to help prevent the disease, however the incidence of FeLV in cats seen at Banfield has only decreased by 1 percent between 2010 and 2014, per SOPH.1

Signs and Treatment of FeLV

Most FeLV infections are caught with routine blood testing. Screening tests can catch the disease before it causes clinical signs. What should you look for?

Signs can vary greatly depending on the individual case, but can include:

  • Chronic infections
  • Diarrhea
  • Nasal discharge
  • Coughing
  • Weight loss

In the case of cancer, the disease can progress quickly and potentially cause death. Unfortunately, there is no known cure for FeLV infection. Regular veterinary care and reporting any signs of illness to your veterinarian as quickly as possible can help extend the length and quality of an infected cat’s life.

How to Prevent FeLV

Ideally, your cat should be kept indoors and away from potentially infected cats. If your cat does have access to the outdoors, it should be tested for FeLV infection annually. A new cat should be tested before it joins your household and kittens should be vaccinated against FeLV, as they are highly susceptible to infection.

Consult your veterinarian to discuss if the FeLV vaccination is appropriate for an adult cat.

Although FeLV can be spread through saliva, the virus does not survive very long in the environment so most common household disinfectants will kill it. In addition to regular screening and vaccinations, it is also important to maintain a clean environment for your cat to live in.

Need More Information?

You can learn more about Feline Leukemia by reading our handout, or visiting the FeLV section of our State of Pet Health Report. For specific concerns about your cat, contact your local veterinarian.


1. State of Pet Health Report. Feline leukemia virus. Banfield Pet Hospital. Portland, Ore. 2014.