TETRAPARESIS DUE TO VERTEBRAL PHYSEAL FRACTURE IN AN ADULT DOG WITH CONGENITAL HYPOTHYROIDISM

A four-year-old male affenpinscher was referred for evaluation of hind limb weakness that had progressed to tetraparesis over a period of fou r weeks. Neurological examination was suggestive of a cervical spinal cord lesion. Radiographic examination revealed diffuse skeletal immatu rity with open physes and epiphyseal dysplasia in long bones and verte brae, consistent with a diagnosis of congenital hypothyroidism. Total and free serum T-4 concentrations were very low, indicative of hypothy roidism. Survey radiographs of the cervical spine revealed a dorsally displaced Salter-Hards type I fracture of the cranial portion of the f ourth cervical vertebra with the endplate present in the vertebral can al. Although signs of transverse myelopathy are uncommon in dogs with congenital hypothyroidism, they may be associated with either interver tebral disc protrusion or endplate displacement into the vertebral can al secondary to the epiphyseal abnormalities associated with congenita l hypothyroidism.