Lymphoma in Cats

Lymphoma in Cats is a cancer of the lymphocytes, a type of white blood cell associated with the immune system. It is one of the most common types of cancer in middle-aged and senior cats. In cats, lymphoma most commonly affects the gastrointestinal tract, but can also occur in any organ in the body, including the lymph nodes, eyes, kidneys, liver, or spleen.

Risk Factors

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) have been shown to increase the risk for developing lymphoma in a cat’s lymph nodes or chest. Fortunately, these viruses have become less common thanks to the testing and isolation of infected cats, and the use of vaccines.

There has also been some research linking owner’s cigarette smoking to feline lymphoma.


Signs vary depending on the location of the disease, but may include:

  • Lack of appetite
  • Lethargy
  • Weight loss
  • Vomiting
  • Diarrhea


The clinical signs of lymphoma are vague. Bloodwork and a urinalysis help to exclude other diseases from the list of possibilities. X-rays and/or an ultrasound may also be performed to evaluate the internal organs  In some cats, a highly specialized test called PARR (PCR for antigen receptor rearrangement) is performed on a biopsy sample to confirm a diagnosis of lymphoma.


If your cat is diagnosed with lymphoma, your veterinarian may refer you to a board certified cancer specialist called an oncologist who will recommend a treatment plan. Treatment depends on the organs involved, but most cases require chemotherapy since the disease is widespread throughout the body.

Veterinary oncologists treat lymphoma using a variety of chemotherapy drugs. Most commonly used is the CHOP protocol. CHOP is an acronym representing the first letter of each chemotherapy drug in the protocol and is repurposed from human oncology. Despite the bad reputation chemotherapy has, most cat owners report a good quality of life in their pet’s receiving chemotherapy.

Surgery and/or radiation may be appropriate for certain cases, but most cannot be effectively treated with surgery or radiation alone. While lymphoma cannot be cured, the disease can often be put into remission, extending your cat’s life for months or even years.


To decrease your cat’s chance of developing lymphoma, avoid smoking around your cat, keep her indoors and away from cats infected with FIV and FeLV. You might also discuss the FeLV vaccination with your veterinarian to see whether it makes sense for your cat.

By The Animal Medical Center