Canine spirocercosis-associated extraskeletal osteosarcoma with central nervous system metastasis.

A five-year-old male Boerboel presented for examination, collapsed for an unknown period of time. On clinical examination, multifocal subcutaneous masses and enlarged prescapular lymph nodes as well as neurological deficits that suggested a multifocal neurological syndrome were found. Fine needle aspirates of the prescapular lymph nodes revealed cells suggestive of osteosarcoma. Radiographs showed foci of mineralisation within the soft tissue masses as well as diffuse pulmonary metastasis and a caudodorsal mediastinal mass believed to be a Spirocerca lupi nodule. Computed tomography imaging, necropsy and histopathology confirmed S. lupi oesophageal neoplastic transformation (extraskeletal osteosarcoma), believed to be the primary lesion, and the majority of secondary metastasis to the brain, spine, heart, multiple muscular groups and abdominal organs. This is the first known report of extraskeletal osteosarcoma metastasis to the brain and spinal cord in a dog.