Response rate after administration of a single dose of doxorubicin in dogs with B-cell or T-cell lymphoma: 41 cases (2006-2008).

OBJECTIVE: To determine the response rate after administration of a single dose of doxorubicin in dogs with B-cell or T-cell multicentric or thymic lymphoma.
DESIGN: Retrospective case series. ANIMALS: 41 client-owned dogs with lymphoma. PROCEDURES: Medical records of dogs in which lymphoma was diagnosed between February 2006 and October 2008 were reviewed. Entry criteria included that dogs had a confirmed lymphoma that was immunophenotyped to be of B-cell or T-cell origin. Only dogs that received doxorubicin alone as their first chemotherapy treatment and were evaluated 1 week later were included in the study. Dogs were excluded when they had received prior treatment with corticosteroids. Medical records were reviewed to obtain signalment, stage and substage of lymphoma, and immunophenotype and to determine whether the dog had hypercalcemia at the time of diagnosis.
RESULTS: Dogs with T-cell lymphoma had a significantly lower response rate to doxorubicin than did dogs with B-cell lymphoma. Twenty-five of 29 (86.2%) dogs with B-cell lymphoma had a complete response, compared with 2 of 12 dogs in the T-cell group that had a complete response. The overall response rate of dogs with B-cell lymphoma was 100%, compared with a response rate of 50% in dogs with T-cell lymphoma. CONCLUSIONS AND CLINICAL RELEVANCE: Standard-of-care chemotherapy protocols for the treatment of dogs with lymphoma include doxorubicin. Many dogs with T-cell lymphoma did not respond to doxorubicin; therefore, multiagent protocols containing doxorubicin may not be optimal. Alternative protocols should be considered for dogs with T-cell lymphoma that do not respond to doxorubicin.