Stages of Canine Lymphoma

Canine lymphoma, or lymphosarcoma (LSA) is a cancerous tumor found in dogs. The cause of lymphoma is unknown and there is currently no cure. This disease causes the normal cells of the immune system to malfunction and attack the lymph nodes. Lymphoma is highly variable in that it can affect one or more of the dog's lymph nodes, leading to rapid progression of cancer affecting the health of entire organs. Generally, the tumor will form a non-painful lump near the affected area(s). As the cancer progresses, symptoms will develop depending upon which organ system is affected. Chemotherapy treatment is often used to achieve remission. Lymphoma can strike dogs of any age or breed, though older dogs and Golden Retrievers seem to be at an increased risk. 

Stages of Canine Lymphoma

Canine Lymphoma is diagnosed in stages. Definitions of these stages are as follows:

  • Stage I: a single lump is discovered affecting one lymph node
  • Stage II: multiple lumps are discovered affecting either the front or back half of the body
  • Stage III: multiple lumps are discovered affecting both the front and back halves of the body
  • Stage IV: the liver or spleen has been affected
  • Stage V: the bone marrow (leukemia) or other organs have been affected

Substages a and b indicate how the symptoms are currently affecting the dog. Substage 'a' indicates that the dog is feeling well. Substage 'b' indicates the dog is showing symptoms and feeling ill. If multiple lumps are discovered, the staging process will require additional testing to determine which areas and organs of the body are cancerous, thus determining a particular stage (I to IV) to diagnose. Tests may include abdominal radiographs, ultrasound, blood tests, urinalysis or bone marrow examination.

Common Forms of Canine Lymphoma

There are five common forms of canine lymphoma, each attacking a specific site of the dog's body.

  • Multicentric: all external lymph nodes are large and firm. Symptoms may be lumps, or mild signs such as lethargy or loss of appetite.
  • Gastrointestinal: the GI tract. Symptoms may include vomiting, diarrhea and weight loss.
  • Mediastinal: affects the chest area. Symptoms may include difficulty breathing, or excessive urination or thirst
  • Extranodal: affects the skin, eyes or other miscellaneous areas. Symptoms may include flaky, scaly, reddened or itchy skin. Foot pads and gums may show ulcerations.
  • Bone Marrow: otherwise known as leukemia. Interferes with red and white blood cell count and causes anemia, infections and bleeding.

What to Expect

Dogs left untreated will likely die within 4 to 6 weeks of diagnosis. Chemotherapy is recommended, however dogs in Stage V often have a very poor prognosis. As a general rule, dogs in Stage V will have a 50% chance of remission with aggressive treatment, Stage IV patients have a 60% to 80% chance, and Stage III patients can expect chances of 80% to 90%. Remission periods may last 8 to 14 months. At that point, the tumor will likely return and can again be treated with chemotherapy. Second remissions are less likely and if successful, will not last as long. At any point, the cancer may become resistant to therapy and no further remissions can be obtained.