Cervical chondroid chordoma in a Shetland sheep dog.

A spayed female Shetland sheep dog aged 12 years was presented for examination with ataxia and hindlimb paralysis. Extradural spinal cord compression was found at the level of vertebrae C6-C7 by radiography and myelocomputed tomography. A jelly-like mass (0.6 x 1.3 cm) was removed surgically. Histopathological findings were characterized by proliferation of vacuolated polygonal cells (physaliphorous cells) in a mucinous matrix and the presence of chondroid tissue shown immunohistochemically to express S-100. The physaliphorous cells were immunolabelled strongly for vimentin and S-100, and weakly for cytokeratin. A diagnosis of canine cervical chondroid chordoma was made. This is considered to be the first report of a chondroid chordoma originating from the cervical region of the spine in the dog.