Hematologic changes associated with weekly low-dose cisplatin administration in dogs

This study prospectively describes the systemic toxicity of cisplatin (20 mg/m(2),IV) when given in weekly doses prior to localized irradiation in dogs with solid malignancies. Eleven dogs received a total of 54 weekly doses of cisplatin. Two dogs did not complete the 5-week protocol due to progressive disease and two dogs received 6 weekly doses of cisplatin. Repeated administration of cisplatin caused a significant decline in the leukocyte count, segmented neutrophil count, and platelet count. These changes were related to the number of cisplatin doses. The dogs did not have any significant alteration of blood urea nitrogen, serum creatinine, or urine specific gravity during the treatment period. Weekly low-dose cisplatin, as used in this study, is safe for use in tumor-bearing dogs. However, the significant decline in the leukocyte, segmented neutrophil, and platelet counts in these 11 dogs suggest that cisplatin prescribed at 20 mg/m(2) IV once per week should not exceed five consecutive treatments.