Stereotactic radiosurgery for treatment of osteosarcomas involving the distal portions of the limbs in dogs.

Stereotactic radiosurgery (SRS) involves precise delivery of a single large dose of radiation to a designated tumor target. This report describes use of SRS in combination with a frameless stereotactic localization system to treat 11 dogs with appendicular osteosarcomas. Five dogs were treated with SRS alone; 6 were treated with a combination of SRS and chemotherapy. Overall median survival time was 363 days (range, 145 to 763 days), with 6 dogs still alive 90, 142, 234, 367, 633, and 763 days after SRS. Limb function was good or excellent in all 6 dogs that were still alive. Results in these dogs suggest that SRS may be a viable option for dogs with appendicular osteosarcoma, with the potential to provide long-term local tumor control and improvement in limb function, especially when combined with chemotherapy. Because of the destructive nature of osteosarcoma and limitations of SRS, dogs with tumors that are small and have caused minimal bone destruction would likely be the best candidates for this procedure.