Lymphoma is one of the most common cancers diagnosed in dogs and cats. It is derived from white blood cells called lymphocytes which serve as part of the body’s immune system. Lymphoma is a disease that typically originates in the lymph nodes but may also involve other organs such as the spleen, liver and bone marrow. Some types of lymphoma progress rapidly and can quickly become life-threatening without treatment while others progress slower and can be managed as a chronic disease.
Dogs: Lymphoma generally affects middle-aged to older dogs although it can occur at any age. The exact cause is not known, although environmental factors as well as genetics may contribute to the development of lymphoma. Some breeds tend to be at higher risk than others. Scottish and Airedale Terriers, Chows, German Shepherds, Poodles, St. Bernards, Bulldogs, Beagles, Boxers, Rottweilers and Golden Retrievers are commonly affected. Dogs typically exhibit initial swelling in lymph nodes under the neck, in front of the shoulders and behind the knees.
Cats: Lymphoma has been linked to young cats with feline leukemia (FeLV) and feline immunodeficiency virus (FIV) although it can affect cats of all ages with or without FeLV or FIV. We generally see lymphoma in cats in the lymph nodes, kidneys, chest, and the digestive tract.
Signs and Symptoms:
Dogs: General signs include painless swelling of lymph node(s). Other signs can include vomiting, diarrhea, increased thirst, depression, lethargy, loss of appetite, weight loss and increased urination. Because lymphoma can affect any part of the body (such as skin, gastrointestinal tract, lungs, etc.), symptoms can vary based on the organ system involved. For example diarrhea and vomiting can be signs of gastrointestinal form of lymphoma. A skin rash that progresses to hairless lesions could be a sign of skin lymphoma.
Cats: Because lymphoma can develop in multiple areas, each location can present different symptoms. If lymphoma is present in the chest, cats may have difficulty breathing, loss of appetite and have a cough. If the kidneys are affected, they may display weakness, increased thirst/urination and vomiting. General symptoms include swollen lymph nodes, lethargy, vomiting and weight loss. Cats typically experience more severe symptoms than dogs.
Dogs: The first step in diagnosing lymphoma often involves cytology (obtaining a sample of cells for examination under the microscopy by a pathologist). In some cases, biopsy provides additional important information. Once the diagnosis is confirmed, we stage the cancer to determine the extent of disease in the body. Staging can involve blood work, urinalysis, radiographs, ultrasound and bone marrow cytology Other diagnostics (flow cytometry, PARR, IHC) can provide information regarding B- or T-cell origin. Staging enables us to determine a course of treatment that is right for your dog.
Cats: As with dogs, the best way to diagnose lymphoma involves cytology or biopsy of cells taken from the affected tissues. Blood work, urinalysis, radiographs and ultrasound will confirm a diagnosis, help us identify abnormalities and determine how widespread the cancer may be. These tests can also help determine the best treatment for your cat.
Dogs: Although not curable, lymphoma in dogs is treatable. Systemic chemotherapy is the preferred treatment but in some cases radiation and surgery may be recommended. With treatment, most dogs experience remission with few side effects. Treatment that has the highest rates of remission involve administering a combination of chemotherapy drugs given over the course of several weeks to months.
Cats: As with dogs, lymphoma in cats is treatable. Chemotherapy and radiation can be effective forms of treatment that we can discuss with you based on the type of cancer diagnosed. In some cases surgery is also an option. Cats tend to tolerate chemotherapy quite well with few side effects.
Dogs: In general, dogs receiving chemotherapy participate in normal activities and have a good quality of life. Our goal is to achieve complete remission while maintaining this good quality. Once your pet completes treatment, we will want to monitor them closely for signs of relapse.
Cats: As with dogs, our goal with treatment is complete remission. Survival and remission rates depend on a number of factors including your cat’s FeLV status, location of tumor and how quickly lymphoma was diagnosed and treated. Cats should be monitored during and after treatment for a recurrence of symptoms.