Canine osteosarcoma is a common bone malignancy associated with aggressive local disease and rapid metastasis. Current local therapeutic modalities do not provide curative-intent options for dogs with significant orthopaedic or neurologic disease, dogs which are denied amputation or dogs with non-resectable lesions. The goals of this retrospective study included the evaluation of local control, survival, and time to the development of metastases in 14 dogs treated with curative-intent radiation therapy and chemotherapy. Median local disease control was 202 days (79-777). Median survival was 209 days (79-781). Median time to metastasis was 314 days (7-645). No significant correlation was found between the outcome and pre-treatment alkaline phosphatase levels, radiographic appearance, tumour site, radiation dose or chemotherapeutics administered. In these dogs, full-course radiation therapy in conjunction with chemotherapy was not found to yield equivalent results to the standard of care options.