Up to twenty percent of all cancers in dogs are some form of lymphoma. (Reference 2) Lymphoma is a type of malignant cancer that most often occurs in dogs who are middle aged and older. (Reference 1, 2, 3, 4) It specifically affects the lymphatic system, which is a vital part of the dog’s immune system. (Reference 1, 3) Lymph nodes and lymphatic tissue is found all over the body including in the skin, the liver, in the neck and in the groin area. (Reference 1, 3)
Types of Lymphoma
Since lymphatic tissue is found in several different areas of the body, there are several different types of resulting lymphoma. (Reference 2) Acute lymphoblastic leukemia involves lymphoma that began in the bone marrow, while cutaneous lymphoma arises from the skin. (Reference 2) Dogs may also have the multicentric form of lymphoma, which arises in the lymph nodes themselves. (Reference 2) Other types of lymphoma include gastrointestinal lymphomas, which can involve one or multiple organs of the gastrointestinal tract, and lymphomas that affect the nasal cavity, the kidneys and the thymus. (Reference 2)
Symptoms of Canine Lymphoma
Unfortunately, only up to twenty percent of dogs who are brought into the veterinarian are displaying symptoms of lymphoma. (Reference 3) An article from the Veterinary & Aquatic Services Department of PetEducation.com notes that the majority of dogs are brought in due to a new lump or swelling that the owner found. (Reference 3) Dogs who do display symptoms can vary greatly due to the numerous locations in which the lymphoma can arise. (Reference 3) Some dogs may produce vomiting, loss of appetite or diarrhea, while others still produce weight loss, shortness of breath or ulcerating lumps. (Reference 3)
The affected dog will undergo a thorough physical examination, in which the veterinarian will check for swelling of other lymph nodes that the owner may not have caught. He will also run blood tests or he may choose to do a biopsy of the affected lymph node or tumor. X-rays and ultrasounds may also be used to confirm and determine the severity of the lymphoma. (Reference 1)
Lymphoma is a systematic disease, meaning that the lymphoma can arise in a single lymph node and spread to all other lymph nodes or other lymphatic tissue within the body. Therefore, the most effective treatment is chemotherapy, as radiation therapy or surgery is generally not practical. (Reference 3) Treatment length using chemotherapy will vary from dog to dog depending on the severity of the lymphoma.
Owners who opt out of treatment can expect their dog to live between four and six weeks, though individual cases can vary based on the severity and location of the lymphoma. (Reference 3) Fortunately, lymphoma treatment is often successful and the dog can expect to live anywhere from a few additional weeks to a year or more. (Reference 3) However, as with any type of cancer, the owner should be aware that the prognosis is only a ‘guesstimate’ of how long the dog may survive and should not be considered a guarantee. (Reference 4)