Diagnosis and surgical management of an extraskeletal osteosarcoma of the brachial plexus in a Belgian shepherd dog.

An 11-year-old Belgian shepherd presented with progressive right thoracic limb lameness. Computed tomography and magnetic resonance imaging revealed a brachial plexus neoplasm and cytology was suggestive of a sarcoma. The patient underwent forequarter amputation and hemilaminectomy of the fifth cervical to first thoracic vertebrae with nerve root transection. Histopathology confirmed extraskeletal osteosarcoma. Twelve months post-operatively, the dog was exercising normally, and computed tomography did not identify local recurrence or metastatic disease. This is the first recorded case of canine brachial plexus extraskeletal osteosarcoma.