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Veterinary Teaching Hospital

Feline Lymphoma

Oncology cat patient

What is lymphoma?

Lymphoma, also known as a lymphosarcoma or LSA, is common in cats and is caused by a cancerous proliferation of lymphocytes, or white blood cells that normally function in the immune system. Any breed of cat can develop lymphoma.

What causes lymphoma in cats?

Feline leukemia virus (FeLV) at one time was a leading cause of lymphoma in cats and typically young cats were infected. Now that the incidence of FeLV has decreased, cats still develop lymphoma, but it is generally older cats and different forms. The feline immunodeficiency virus (FIV) has also been shown to increase the risk of a cat developing lymphoma six times over a non-infected cat.

The cause of the disease unrelated to FeLV or FIV is unknown, although environmental smoke exposure has been found to increase risk and a possible link to long-standing inflammatory disease has been theorized. 

What are some signs my cat has lymphoma?

Cats with lymphoma present with a variety of signs because lymphocytes can be found in nearly every organ in the body. Compared to other species, cats seem to have more forms of lymphoma in atypical locations or not in normal lymphoid tissues. Most species present with large lymph nodes, but this is a rare form in cats.

Young cats typically present for masses in the chest cavity and owners notice signs of difficulties breathing or vomiting of food. Older cats commonly develop the tumor in their intestines and owners may notice weight loss, diarrhea, or vomiting. Lymphoma can also develop in nasal passages, kidneys, spinal cord, liver, eyes, or a single lymph node, and the signs seen are more specific to the organ affected.

How is lymphoma diagnosed?

Lymphoma is often diagnosed with a biopsy, a minor surgical procedure to remove a piece of a lymph node or other organ that may be affected by cancer; thoracic and abdominal radiographs; ultrasound (to look for big nodes in the abdomen and to look at the liver and spleen); or bone marrow examination. Obtaining blood for a complete blood count and biochemical profile, testing for FeLV and FIV, and a urinalysis is always advised, as these can help assess overall health and provide information that potentially influences treatment recommendations. Special stains to determine if the lymphoma is of B-cell or T-cell origin are sometimes recommended.

How is lymphoma treated?

Chemotherapy should always be considered a critical part of the treatment for lymphoma. The best responses in terms of length of tumor control and survival are generally seen with the use of more than one chemotherapy drug, although there are approaches that involve a single drug. Chemotherapy drugs commonly used include doxorubicin, vincristine, cyclophosphamide, prednisone, and L-Aspariginase.

Some treatments are very aggressive and relatively short (six months in total) and others are less aggressive but extend for one to two years, depending on the results of testing.

Chemotherapy generally acts quickly and even cats with severe signs can have relief soon after starting therapy, sometimes as quickly as 24 hours. Surgery is occasionally recommended as a part of treatment, but this is usually either to reach a diagnosis or to remove a potentially life-threatening problem (for example intestinal rupture due to a tumor mass). Surgery is never curative and should always be followed by chemotherapy. Radiation can also play a role in the treatment of very localized lymphoma.

What is the prognosis for a cat with lymphoma?

Cats with lymphoma have unpredictable responses and survivals. Depending on the site of the tumor, mean survivals with chemotherapy range from 6-9 months. The problem is that this is only an average and most cats tend to do either much worse or much better. Young, FeLV negative cats with mediastinal lymphoma are quite regularly cured with chemotherapy, but cats with lymphoma in their central nervous system typically have a bad prognosis. Most other forms of lymphoma in cats have unpredictable outcomes. 

Lymphoma is one of the most chemotherapy-responsive tumors seen in veterinary medicine and cats can tolerate chemotherapy relatively well. Unfortunately, there few strong predictors of which cats will have good responses to chemotherapy and long survivals, and survival is therefore difficult to estimate at the outset. Starting treatment is often the only way to know how a cat will respond.

Lymphoma is viewed as a systemic disease since lymphocytes in their normal functioning travel throughout the body, meaning the cancer is also moving, though not metastasizing in a classical sense. Even if a tumor diagnosed as lymphoma has been surgically removed, the disease is not gone.

Where can I get help if my cat has lymphoma?

Cancer of any kind is a diagnosis no pet owner wants to hear, but our board-certified veterinary oncologists can help you get an accurate diagnosis and develop a treatment plan. Call 509-335-0711 to schedule an appointment or visit our oncology webpage for more information.


This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.