Canine periosteal osteosarcoma

Osteosarcoma is the most common bone tumor in dogs. The periosteal osteosarcoma is a subtype of osteosarcoma, and is considered rare in the canine species. The purpose of the present study was to describe a 14-year-old female dog with an ulcerated mass located in the right tibia and 30-days of evolution. The patient was submitted to complementary exams (blood count analysis, dosage of biochemical enzymes - creatinine and alanine aminotransferase, thoracic radiographs, and abdominal ultrasonography) to perform complete staging of the disease. Radiography of the right tibia revealed proliferative and lytic periosteal reaction. The cytological analysis of the mass suggested a round cell tumor. The clinical and the radiological findings indicated the presence of a bone tumor. Pelvic limb amputation was the initial surgical treatment suggested to the client. The histopathological examination revealed the presence of periosteal osteosarcoma with free margins and lymph nodes without evidence of tumor cells. Clinical follow-up was performed through imaging exams without evidence of metastatic disease. The dog had a nine-month survival free time from diagnosis.