Lymphoma is the third most common cancer in dogs. Two of the most commonly affected breeds include the Labrador and Golden Retrievers. Fortunately it is considered to be one of the most responsive tumors to chemotherapy. Reported remission rates of 80 to 90% may be obtained with standard chemotherapy protocols. Remissions of between eight and 12 months on first rounds of chemotherapy are characteristic
Characteristically shorter-term protocols are preferred (from 12 to 24 weeks). The theory is that drug resistance may be delayed when lymphoma cells are continuously being exposed to chemotherapy. Short-term protocols have the advantages of being less expensive; they require fewer visits and have potentially less side effects.
Decisions on which chemotherapy protocol to use depends on the anatomic location of the lymphoma, stage and grade of the tumor, as well as the existence of hypercalcemia or a mediastinal mass.
First time remissions are easier to achieve and treatment protocols are more standardized. When considering a rescue protocol (subsequent chemotherapy protocol) several factors must be considered. How long was the first remission? What side effects occurred during the first treatment and what is the general clinical status of the patient at present.
Most rescue protocols are administered and characteristically achieve less than six months increase in remission rates and no more than a year at best, dependent on whether the patient continues to respond to treatment.
North Carolina State University has recently instituted a bone marrow transplant program with an expected cure rate of 50% of those dogs receiving treatment. Procedure costs are expected to run approximately $15,000 for the transplant alone and this figure does not include the chemotherapy and radiation treatments necessary before harvesting and reintroduction of healthy stem cells transplant occurs. Currently only dogs weighing at least 55 pounds are eligible for bone-marrow transplants.
The most common side effects of treatment are related to chronic myelosuppression particularly thrombocytopenia which may lead to bleeding.
Cronin, Kim, DVM. “What’s Next? Rescue Protocols for Canine Lymphoma”. DVM. Pp. 12S-16S.
“NCSU to offer Bone-Marrow Transplants for Dogs with Lymphoma.” DVM Newsmagazine. P. 12S. October 2008.