High-dose methotrexate and leucovorin rescue in dogs with osteogenic sarcoma

Five dogs with ostoegenic sarcoma were treated by surgical removal of the primary tumor and by adjuvant chemotherapy. Methotrexate at dosages of 3 to 6 g/m2 was used with leucovorin rescue. All dogs tolerated E g of methotrexate/m2 of body surface, but granulocytopenia precluded escalation beyond this dosage in 4 dogs. The rate and time of appearance of pulmonary metastases were not altered by treatment, with all dogs developing metastases at a median time of 4 months after amputation.