Randomized controlled trial of doxorubicin versus dactinomycin in a multiagent protocol for treatment of dogs with malignant lymphoma

Objective - To compare efficacy and toxicity of 2 multiagent chemotherapeutic protocols similar in all respects except that 1 incorporated dactinomycin and the other incorporated doxorubicin for treatment of dogs with malignant lymphoma. Design - Randomized controlled trial. Animals - 45 dogs with malignant lymphoma. Procedure - Dogs were randomly assigned to a doxorubicin or dactinomycin treatment group. Time to first remission, duration of first remission, survival time, and prevalence of toxicoses, particularly number of episodes of dose-limiting neutropenia and gastrointestinal toxicoses, were compared between groups. Results - 37 dogs received at least 1 dose of doxorubicin (21 dogs) or dactinomycin (16). Median time to first remission was not significantly different between groups, but median duration of first remission and median survival time were significantly longer for dogs in the doxorubicin treatment group than for dogs in the dactinomycin treatment group. Number of dogs that died, number of episodes of dose-limiting neutropenia, and number of episodes of gastrointestinal toxicoses were not significantly different between groups. Clinical Implications - A multiagent chemotherapeutic protocol incorporating doxorubicin was significantly more effective in dogs with malignant lymphoma than a similar protocol incorporating dactinomycin. Despite the lower cost and lack of cardiotoxicity, dactinomycin is not an equivalent substitute for doxorubicin in the initial treatment of dogs with malignant lymphoma.