Osteochondroma causing progressive posterior paresis in a lakeland terrier puppy.

A lakeland terrier puppy had progressive hindlimb ataxia associated with pain in the thoracic spine. Plain radiographs revealed a lesion affecting the dorsal neural arch of the fourth thoracic vertebra and myelography revealed compression of the spinal cord associated with the lesion. Surgical excision of the mass cured the dog's clinical signs. A histopathological examination of the excised tissue supported a diagnosis of osteochondromatosis.