Lymphoma is one of the most common cancers seen in dogs. In fact, we estimate that lymphoma occurs about 2 to 5 times as frequently in dogs than in people. Although there are breeds that appear to be at increased risk for this disease, lymphoma can affect any dog of any breed at any age. It accounts for approximately 20% of all canine tumors, and less than 80% of cancers originating from blood cells.

Most of the time, lymphoma appears as “swollen glands” (lymph nodes) that can be seen or felt under the neck, in front of the shoulders, or behind the knee. Occasionally, lymphoma can affect lymph nodes that are not visible or palpable from outside the body, such as those inside the chest or in the abdomen. In these cases, dogs may accumulate fluid in the chest that makes breathing difficult, or they may have digestive problems (diarrhea, vomiting, or painful abdomen). If left untreated, dogs with lymphoma will generally succumb to the disease within 3 to 4 weeks.

Treatment with prednisone (a corticosteroid) alone generally can induce short-lived remissions (usually less than 8 to 12 weeks), but frequently renders the disease resistant to further treatment. Durable remissions are achievable in lymphoma, so the disease is considered “treatable.”

Multi-agent chemotherapy consisting of L-asparaginase, vincristine, cyclophosphamide, doxorubicin, and prednisone, which is the standard-of-care for this disease, will induce remissions of 12 to 18 months in many cases. However, there are various subtypes of lymphoma that exhibit different behaviors, and some of the more aggressive types are unresponsive to any available treatment.