Introduction
Canine malignant lymphoma, also known as lymphosarcoma or lymphocytic leukemia, is a progressive and very serious disease cause by abnormal proliferation (growth) of cells in the lymphatic system. It often involves cells in the bone marrow, thymus, lymph nodes and/or spleen. It also can show up in the skin, eyes, central nervous system, testes and bone. Lymphoma is reported as being the most common hematopoietic neoplasia in dogs. “Hematopoietic” means pertaining to the formation of blood cells, and “neoplasia” basically refers to what commonly is called “cancer” – any new, abnormal, uncontrolled and progressive tissue growth.
Lymphoma can affect male and female dogs of all breeds, and its causes remain unknown. There may be a genetic link, because Boxers, Golden Retrievers, Scottish Terriers, Basset Hounds, German Shepherds, Saint Bernards, Airedale Terriers, Bull Dogs, Poodles and Old English Sheepdogs seem to be affected at a higher rate than other breeds. Certain lines of Bull Mastiffs, Rottweilers and Otter Hounds also seem to be predisposed to this type of cancer. There are several types of lymphoma in dogs and cats, which can affect the skin, the central nervous system, the gastrointestinal tract and/or the entire body. This article summarizes the common, multicentric and system-wide type of lymphoma found in dogs.
How Lymphoma Affects Dogs
Clinical signs of lymphoma are nonspecific and varied. Usually, what owners notice first is pronounced enlargement of lymph nodes in their dog’s neck. The dog normally is not painful on palpation and shows no other unusual symptoms. The disease progresses rapidly, causing most dogs to develop depression, fever, lethargy, weight loss, inappetence and vomiting.
Causes of Canine Lymphoma
The cause of lymphoma is not known. There may be a genetic component, because certain breeds are disproportionately affected.
Diagnosing Canine Lymphoma
Canine lymphosarcoma is diagnosed through a physical examination and blood tests (a complete blood count and serum chemistry panel), including an in-depth look at circulating blood cells on a microscopic level. Additional tests such as evaluation of bone marrow and microscopic examination of lymph tissue are used to definitively diagnose this progressive disease. Accurate confirmation of lymphoma usually requires lymph node biopsy, chest radiographs (x-rays), abdominal ultrasound, bone marrow aspiration and/or other cutting-edge diagnostic procedures. Your veterinarian can walk you through these various diagnostic options.
Preventing Lymphoma in Dogs
There is no known way to prevent lymphoma.
Special Notes
While chemotherapy can extend a dog’s life after a diagnosis of malignant lymphoma, the disease tends to be progressive. However, most dogs with lymphoma do go into remission following focused chemotherapy, and therefore it is really important to explore this treatment with your veterinarian. For some reason, female dogs tend to respond better to treatment than do males, and small dogs seem to do better than large ones.