Feline lymphoma or cancer in cats
Lymphoma is a type of cancer that affects lymphocytes, which are important cells in a cat’s immune system. These cells travel throughout the body in the blood and lymphatic vessels. One of the main causes of lymphoma in cats is feline leukaemia virus (FeLV), a contagious viral infection. Fortunately, we can protect cats from this virus with a vaccination.
Lymphoma can affect any breed, but Siamese cats (especially males) have a higher chance of developing it.
Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published May 2025 | Review date May 2027 | This advice is for UK pets only and is not a replacement for seeing a vet
Cat lymphoma or cancer symptoms
The most common form of lymphoma is intestinal lymphoma. Cats with intestinal lymphoma will have gastrointestinal signs, such as:
Vomiting
Weight loss
Diarrhea
Lethargy
Eating habit changes
The tummy may change in shape and size
Other forms of lymphoma outside the digestive system have varying signs, depending on which system is
affected. These include mediastinal (chest) lymphoma and renal (kidney) lymphoma.
When to contact your vet
Contact your vet for an appointment if your cat has any of the symptoms listed above.
Diagnosis
Collecting a sample of the cancerous cells and sending it off to the lab
Blood tests including blood cell counts, organ function, and whether they have feline leukaemia virus
Diagnostic imaging, like X-rays, ultrasound, or a CT scan
Treatment for lymphoma in cats
Lymphoma is usually treated with chemotherapy:
Low-grade lymphoma is treated with steroid and chemotherapy drugs.
High-grade lymphoma is treated using one of several injectable chemotherapy protocols.
Cats tolerate chemotherapy much better than humans; they rarely lose their hair or appear sick.
The most common side effects include vomiting, diarrhoea, and decreased appetite. However, these effects are seen in a small percentage of patients.
If chemotherapy is not an option due to a cat’s illness or owner’s finances, steroids can be used for palliative, although steroids do not treat lymphoma, it can temporarily reduce clinical signs and buy your pet more time.
Prevention
Feline leukaemia virus is linked to the development of several forms of lymphoma. Regular vaccination for leukaemia can keep your cat safe from the virus that increases their risk of developing lymphoma.
If you smoke, avoid smoking in the house and exposing your cat to secondhand smoke, as it may double their risk of developing this cancer.
Outlook
The prognosis for lymphoma depends on the location of the lymphoma, how sick the cat is at the start of treatment, the cat’s feline leukaemia status, and how quickly the disease is diagnosed and treated.
Most cases of gastrointestinal lymphoma are low-grade lymphoma. With treatment, approximately 70% of cats with low-grade lymphoma will go into a temporary resolution of all signs of lymphoma(remission). Lymphoma is never truly cured. The average remission for low-grade lymphoma is two to three years, meaning two to three years without any signs of disease.
High-grade gastrointestinal lymphoma, however, does not respond as well to treatment. Only 25-50% of cats with high-grade lymphoma achieve remission with treatment. Typically, this period of remission lasts only 2-9 months, and then cats become ill again.
Mediastinal lymphoma in cats with feline leukaemia carries a poor prognosis, with an average survival time of 3 months. In cats without feline leukaemia, mediastinal lymphoma often shows at least a partial response to chemotherapy. Renal lymphoma, unfortunately, carries a poor outlook. Renal lymphoma tends to spread to the brain and central nervous system.