An 11 kg, 7-year-old male pug dog with lameness and tumor of the 2-3rd interdigital portion of the right forelimb was referred to the Veterinary Medical Center of the Tokyo University. On the clinical examination findings, the tumor size was $3{ imes}3 cm but alopecia and necrosis were not found. On the radiological findings, a bone lysis was found in the phalanges of digit II of the right forelimb but pulmonary metastasis was not found. The mass was removed with metacarpal bone. Histopathological examination of the mass revealed highly differentiated hemangiopericytoma. Two weeks after the operation, the dog was irradiated by orthovoltage radiation. The source of irradiation was 300 kV, 4mA, 4Gy and a focal spot to skin distance of 40 cm using 1.0 Cu, 1.0Al filter. The radiation therapy was performed twice a week for 5 weeks. The dog showed no recurrence and no metastasis. It was thought that the surgery and radiation therapy treatment was quite a useful method to treat a canine heman-giopericytoma.