Prophylactic trimethoprim-sulfadiazine during chemotherapy in dogs with lymphoma and osteosarcoma: a double-blind, placebo-controlled study.

Background: The administration of chemotherapy is associated with risk for morbidity. Management of chemotherapy-related morbidity in veterinary oncology has been primarily supportive. Hypothesis: The purpose of this study was to evaluate the effect of prophylactic antimicrobial use on chemotherapyassociated morbidity in dogs with lymphoma or osteosarcoma. Animals: Dogs presenting with histologically confirmed osteosarcoma or lymphoma were eligible. Methods: Patients were randomized to receive placebo or trimethoprim-sulfadiazine for 14 days after their first doxorubicin chemotherapy. Both owner and clinician were blinded with respect to treatment. Patient assessment included CBC, physical examination and performance, and toxicosis grading on days 7 and 14. Investigated outcomes were hospitalization, suspicion of infection, gastrointestinal toxicity, neutropenia, nonhematologic toxicity, and quality of life. Results: Seventy-three dogs were enrolled; 34 had osteosarcoma, and 39 had lymphoma. Dogs receiving trimethoprim-sulfadiazine (n = 36) had a significantly reduced hospitalization rate (P = .03), nonhematologic toxicity (P = 0.039), grade 2-4 nonhematologic toxicity (P < .0001), grade 2-4 gastrointestinal toxicity (P = .007). and altered performance (P = .015). By group, dogs with osteosarcoma (n = 34) that received the antimicrobial experienced fewer Occurrences of nonhematologic toxicity (P = .02) and less severe nonhematologic toxicity (P = .038). Dogs with lymphoma (n = 39) had significant reductions in the occurrence or hospitalization (P = .035), severity of nonhematologic toxicity (P = .036), and alterations of performance (P = .015). Conclusions: The use of prophylactic trimethoprim-sulfadiazine has benefit in reducing morbidity in dogs with osteosarcoma or lymphoma during the first 14 days after treatment with doxorubicin.