Feline leukemia virus (FeLV) is one of the most common viral infections among cats, affecting 2-3% of all cats. That percentage increases among cats that are at a higher risk of infection. However, with the discovery of the FeLV vaccine, most cats are protected against infection. At East Valley Animal Hospital in Gilbert, AZ, we recommend getting all kittens vaccinated for FeLV because of the high risk of infection. If you have an adult cat, we’ll help you determine the risk of your furry friend and recommend vaccinations as needed. 

What is Feline Leukemia Virus?

Unlike leukemia in humans, which is classified as a cancer, feline leukemia is a viral disease that is spread from cat to cat and can lead to cancer, in addition to other health conditions. Once contracted, the disease weakens the immune system, causes blood disorders and is the most common cause of cancer in cats. 

Methods of Infection 

Feline leukemia virus is found in saliva, nasal secretions, urine, feces and milk of infected cats. The virus can be spread from cat to cat through the following methods: 

  • Bites
  • Mutual grooming
  • From a mother to her kittens
  • On occasion, through the shared use of litter boxes and food dishes

Clinical Signs of Infection

When a cat is initially infected with feline leukemia, they may show few to no symptoms. But as the disease progresses, a cat may show any of these clinical signs of infection: 

  • Loss of appetite
  • Persistent diarrhea
  • Weight loss
  • Pale gums 
  • Poor coat condition
  • Enlarged lymph nodes
  • Persistent fever
  • Inflammation of the gums (gingivitis) and mouth (stomatitis)
  • Infections of the skin, urinary bladder, and upper respiratory tract
  • Seizures and other neurological disorders

Stages of Infection & Life Expectancy

There are three stages of FeLV infection: abortive, regressive and progressive. About one-third of infected cats will reach the progressive stage. 

Abortive stage. In the abortive stage, a cat’s immune systems effectively eliminates all traces of the disease.  

Regressive stage. In the regressive stage, the virus temporarily enters the bloodstream and has access to the rest of the body. The cat eventually clears the virus and does not become ill from FeLV-associated diseases, however, they will carry the FeVL DNA in their bone marrow. While they are not infectious to other cats at this stage, the virus may be reactivated in the future. 

Progressive stage. In the progressive stage, infected cats have the FeLV virus in their bloodstream and may pose a risk of infection to other cats. Progressively infected cats can survive from months to years, but they will eventually die from FeLV-associated diseases, as there is no cure. With proper management and veterinary care, a FeLV-infected, indoor-only cat can still have a good quality of life until the end.

Caring for FeLV Positive Cats in Gilbert 

Currently, there is no definitive cure for feline leukemia. Certain therapies may be undertaken to limit the impact of the virus on the body, but they sometimes come with harsh side effects. Most treatments for FeLV seek to manage specific illnesses associated with the disease. 

Before introducing a new cat to your household, you should always have them tested for FeLV. In multiple-cat households, if a cat tests positive for FeLV, they should ideally remain separate from the rest. 

At East Valley Animal Hospital, we know that a FeLV positive diagnosis can be devastating for a cat owner. Our team is committed to compassionately working with each owner and individual cat when it comes to treatment options and offering the best possible life for your feline. 


Image by Andreas Lischka from Pixabay (9/5/2019)