Comparison of the percentage of the C3-C7 vertebral canal occupied by the spinal cord in small-breed dogs with that in Doberman Pinschers and Great Danes with and without cervical spondylomyelopathy.

OBJECTIVE To compare the percentage of the C3-C7 vertebral canal occupied by the spinal cord in small-breed dogs with that in Doberman Pinschers and Great Danes with and without cervical spondylomyelopathy (CSM). ANIMALS 30 small-breed dogs (body weight, < 15 kg), 15 clinically normal Doberman Pinschers, 15 Doberman Pinschers with CSM, 15 clinically normal Great Danes, and 15 Great Danes with CSM. PROCEDURES In a retrospective study, sagittal and transverse T2-weighted MRI images of the cervical (C3 to C7) vertebral column obtained from dogs that met study criteria and were free of extensive abnormalities that could affect the spinal cord diameter between January 2005 and February 2015 were reviewed. The area and height of the vertebral column and spinal cord were measured at the cranial and caudal aspect of each vertebra from C3 to C7, and the percentage of the vertebral canal occupied by the spinal cord at each location was calculated and compared among groups of dogs. RESULTS Mean percentage of the vertebral canal occupied by the spinal cord was greatest for small-breed dogs and lowest for Great Danes, but did not differ between Doberman Pinschers and small-breed dogs at approximately half of the locations evaluated or between Doberman Pinschers with and without CSM or between Great Danes with and without CSM. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the percentage of the vertebral canal occupied by the spinal cord, although expected to increase with vertebral canal stenosis, may not have a primary role in the pathogenesis of CSM.