Home » Pet Health » Feline Infections and Viruses » What are the Signs and Symptoms of FeLV?


Common symptoms and signs of feline leukemia virus (FeLV) infection vary between cats. What the disease looks like can depend on several factors. These may include your cat’s age, genetics, how they become infected, and how much exposure they have. Your cat may also be at risk if they are under stress, have other infections, or is receiving any medications. When the virus first infects your cat, you may notice that your cat has a fever, is tired, has swollen lymph nodes, or all three symptoms at once. Once virally infected immune cells reach the bone marrow, the infection becomes more severe. Furthermore, infected salivary glands mean the virus can be transmitted efficiently in the saliva to other cats.

On rare occasions, the cat’s immune system may fight the disease without showing symptoms, and the infection resolves. However, it is more likely that your cat may show one or more of the following signs:

    • Fatigue
    • Fever
    • Tiny red spots on the skin
    • Persistent diarrhea
    • Swollen or enlarged lymph nodes
    • Weight loss
    • Inflammation in the mouth
    • Skin abscesses
    • Wheezing, sneezing, and difficulty breathing

If your cat shows two or more of these symptoms, it is essential to take them to the vet for testing. It may not be FeLV, but it is good to have it checked so you know how to proceed with treatment if necessary.

If FeLV persists, your cat is at risk of developing more severe diseases such as neurologic problems, reproduction issues, anemia, gastrointestinal problems, conditions associated with dysfunction in the immune system, including chronic infections, and cancers such as lymphoma, leukemia, and fibrosarcomas.

Fortunately, many therapies are available to treat the symptoms resulting from FeLV. Vets recommend keeping your infected cat indoors to protect other cats from infection. Additionally, if you can provide your cat with a stress-free environment and a healthy diet, this will improve their recovery.

To prevent your cat from contracting FeLV in the first place, you can consider housing them inside. However, if your cat escapes, you want them to be protected. Therefore, you can think about vaccination. Several vaccines available have shown substantial efficacy, provided you vaccinate your cat early. Talk to your vet about vaccines and what is most appropriate for your cat.

The Pet Cancer Foundation’s Website Editorial team is comprised of veterinarians, veterinary oncologists, and veterinary technicians, as well as scientific writers and editors who have attained their PhD’s in the life sciences, along with general editors and research assistants. All content found in this section goes through an extensive process with multiple review stages, to ensure this extended resource provides pet families with the most up-to-date information publicly available.

The team listing of those contributing to the information on this page is here:

Keep Your Pets Healthy Editorial Team

Last Updated: October 9, 2022

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.

The Pet Cancer Foundation’s Medical Illustration team is comprised of medical illustration specialists and graphic designers that work in consultation with our team of experts to create the medical art found throughout our website. Though not all medical concepts require the assistance of imagery, when a page does contain a medical illustration, credit to the artist and our medical art director will be noted here.

The Pet Cancer Foundation’s medical imagery is protected by copyright and cannot be used without prior approval that includes a mutually signed licensing agreement. Please review our Content Usage Policy.

The following sources were referenced to write the content on this page: 

Hartmann, K & Hofmann-Lehmann R 2020, ‘What’s new in feline leukemia virus infection’, Vet Clin North Am Small Anim Pract, vol. 50, no. 5, pp. 1013-1036.

Hartmann, K 2012 ‘Clinical aspects of feline retroviruses: a review’, Viruses, vol. 4. No. 11, pp. 2684-2710.

Richards, JR, Elston, TH, & Ford, RB 2006, ‘The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel report’, J Am Vet Med Assoc, vol 229, pp. 1405-1441.

Sykes, JE & Hartmann K 2014, ‘Feline leukemia virus infection’, Canine and Feline Infectious Diseases, pp. 224–238.

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.