Lymphoma in Cats

Lymphoma is cancer of the lymphocytes, a specific type of white blood cell.  They are the major cells in lymph nodes.  A cat's lymphatic system is comprised of vessels and nodes throughout its body.  The lymphatic system is responsible for transporting life-sustaining substances and keeping harmful agents from circulating throughout a feline's body.  According to PetMD, lymphoma is responsible for 33% of all tumors in cats and 90% of all feline blood cancers.

Types of Lymphoma and Their Symptoms

Though lymphoma can occur at any site in a feline's body, it tends to show up in certain places more than others.  Additionally, cats with the feline leukemia virus (FeLV) and the feline immunodeficiency virus (FIV) are at greater risk for developing certain types of lymphoma than uninfected cats.

Multicentric: In this type of lymphoma, multiple lymph nodes and possibly multiple organs are affected.  This type of lymphoma is often associated with feline leukemia virus.  Symptoms of this type of cancer may include swelling of the lymph nodes in the groin, under arms, and jaw, weight loss, depression, and loss of appetite.  

Mediastinal: This type of cancer is found in the chest cavity and affects the thymus and associated lymph nodes.  It has historically affected cats with feline leukemia, though vets are beginning to see more cats without FeLV present with this type of lymphoma.  Symptoms of mediastinal lymphoma include weight loss, cough, open-mouthed breathing, and loss of appetite.  

Alimentary (Gastrointestinal): Alimentary lymphoma affects the gastrointestinal tract and its surrounding lymph nodes.  It is the most common type of lymphoma in cats and is often associated with a FeLV negative status.  Most alimentary lymphoma cat patients are 9 to 13 years old with a history of weight loss, lack of appetite, vomiting, and/or diarrhea.  Additional symptoms can include black or tarry stool, fresh blood in the stool, constipation, and lethargy.

Renal: The kidneys and associated lymph nodes are affected with this type of cancer.  Symptoms of renal lymphoma include vomiting, lack of appetite, weakness, and increased thirst and urination.

Diagnosis

If you notice any of the symptoms described above, it's best to take your cat to your veterinarian for a complete physical exam.  Your vet will take a detailed history of your cat's symptoms in order to determine which tests are most appropriate to perform.  Blood tests, such as a complete blood count and chemistry profile, and a urinalysis are often the first to be done.  Testing for feline leukemia virus and feline immunodeficiency virus are also often done.  X-rays or ultrasounds and biopsies may also be conducted to pinpoint the location of the lymphoma and to test its malignancy.  

Treatment

Treatment will depend largely on the type of and stage of lymphoma your cat has.  Chemotherapy is most often used in the treatment of this type of cancer.  However, radiation and surgery may also be options.  

Chemotherapy is generally tolerated well by cats.  Nausea and vomiting occasionally occur as side effects to this type of treatment.  However, the most common side effect of chemotherapy in cats is bone marrow suppression.  In a small percentage of cases (1-2%), this may lead to life-threatening infections that require a hospital stay.  

While lymphoma is not a curable condition, remission can be achieved with treatment.  Prognosis depends largely on the location of and stage of the lymphoma as well how a cat responds to treatment.

Sources:

Cornell University College of Veterinary Medicine: Lymphoma.

Southwest Veterinary Oncology: Feline Lymphoma.

PetMD: Cancer of the Lymphocytes in Cats.

IVG Hospitals Feline Lymphoma.