Stages of Canine Lymphoma

What the stages mean for you and your dog.

November 19, 2021
3 min read

When your dog has been diagnosed with lymphoma, follow-up tests can determine the stage of the disease. Knowing the stage of the cancer will allow your vet to give the best treatment.

Stage I

A single lymph node or tissue in one organ is affected. This stage is the most difficult to identify, so it is important to know where canine lymph nodes are located. Lymph nodes run throughout the body but swollen nodes are easiest to identify in a dog’s neck below their jaw (submandibular), in their chest (prescapular), their armpits (axillary), groin (inguinal), and behind their knees (popliteal).

Stage II

Lymph nodes in only one half of the body are affected. Veterinarians make this distinction by dividing the body at the canine’s diaphragm. Multiple lymph nodes in the front half or the back half of the body will be targeted in Stage II.

Stage III

Lymphoma identification and diagnosis in canines becomes more prevalent in Stage III. Generalized lymph node involvement in both the front and back halves of the body is seen and is easier to identify because more of the body is affected.

Stage IV

If the lymphoma reaches the liver or spleen, it is categorized as Stage IV. Your dog may or may not have swollen lymph nodes around the body at this stage. Stage III and Stage IV are the most commonly diagnosed stages in dogs.

Stage V

Lymphoma in the blood, nervous system, bone marrow, or any other organ is identified as Stage V canine lymphoma. This is the most advanced stage of lymphoma diagnosis, and therefore treatment is often least successful.


Additionally, canine lymphoma development is divided into substages A and B for each stage above. Substage A is identified when there are no signs of illness. The dog may be feeling well and shows no symptoms of the disease. A dog experiencing Substage B shows symptoms including loss of appetite, weight loss, and abnormal exhaustion.

Stage numbers increase by the amount of the body affected, as they do for human cancer. The World Health Organization (WHO) devised the five-stage naming system for canine lymphoma similar to the human system for cancer stages. Keep in mind that higher stage numbers do not always mean worse symptoms, remission is possible at any stage, and every dog’s experience is different.

Early diagnosis and treatment are advantageous for all cases. Patients experiencing Substage A will eventually reach Substage B and veterinarians concur that there is a higher chance of survival if the dog is treated while in Substage A. Know the symptoms associated with canine lymphoma and when to raise your concerns with your veterinarian. Your veterinarian or oncology specialist will help you decide the best plan for you and your dog.