Practical Matters: Completely stage dogs with lymphoma to select therapy and help determine the prognosis

Selecting appropriate chemotherapy protocols and successfully treating dogs with lymphoma require complete clinical staging of the disease. A complete blood count, serum chemistry profile, and urinalysis, along with a two-view survey radiographic examination of the thorax and abdomen, will help you provide a prognosis to a pet owner. Core or excisional biopsy of one or more lymph nodes is essential before starting treatment.

Most oncologists and reports suggest that dogs with stage I (single node involvement) and II (regional node involvement) lymphoma fare better than those with stage IV (liver, spleen, other visceral involvement) and V (bone marrow, ocular involvement) lymphoma. Dogs with high- to medium-grade stage III (generalized lymph node involvement, multicentric) lymphoma often have good initial responses to treatment. However, cures are still rare, and most dogs survive an average of one year after treatment, with 25% living two years or longer.

It is important to realize that some dogs survive long-term despite having negative prognostic indicators and that some dogs that do not have the negative indicators do not have long-term survival. Dogs that are clinically ill have a poorer prognosis than those without systemic illness. T-cell tumors generally warrant a poorer prognosis than B-cell tumors do. Cutaneous, alimentary, and bone marrow sites of involvement are associated with a poor prognosis, as are male sex, hypercalcemia, and a history of corticosteroid therapy. Dogs weighing less than 33 lb (15 kg) reportedly have a better prognosis than larger dogs, likely because administering chemotherapy drugs on a m2 basis provides a relatively larger area under the curve for the drugs and, hence, higher overall drug exposure in small dogs.

Kevin A. Hahn, DVM, PhD, DACVIM (oncology)

Gulf Coast Veterinary Specialists

1111 W. Loop South, Suite 150

Houston, TX 77027