• Dog;
  • Malignant histiocytosis;
  • Mammary carcinoma;
  • Osteosarcoma

Paclitaxel (Taxol ®) was administered to 25 dogs with histologically confirmed malignant tumors at a dosage of 165 mg/m2 IV over 3–6 hours every 3 weeks. Dogs received premedication with antihistimines and corticosteroids to reduce hypersensitivity reactions. However, 64% of the dogs still experienced allergic reactions. Six dogs (24%) had grade 3 or 4 neutropenia, 6 dogs (24%) required hospitalization and 3 dogs (12%) died of sepsis. Five dogs (20%) had a partial response (osteosarcoma [2 dogs] mammary carcinoma [2 dogs] and malignant histiocytosis [1 dog]) for a median duration of 53 days. The overall toxicity was unacceptable at the 165 mg/m2 dose. Therefore, subsequent evaluations of paclitaxel in tumor-bearing dogs should a starting dose of 132 mg/ m2 IV every 3 weeks.