Computed tomographic evaluation of cervical vertebral canal and spinal cord morphometry in normal dogs

Abstract

The height, width, and cross-sectional area of the vertebral canal and spinal cord along with the area ratio of spinal cord to vertebral canal in the cervical vertebra were evaluated in images obtained using computed tomography (CT). Measurements were taken at the cranial, middle, and caudal point of each cervical vertebra in eight clinically normal small breed dogs (two shih tzu, two miniature schnauzers, and four mixed breed), 10 beagles, and four German shepherds. CT myelography facilitated the delineation of the epidural space, subarachnoid space, and spinal cord except at the caudal portion of the 7th cervical vertebra. The spinal cord had a tendency to have a clear ventral border in the middle portion of the vertebral canal and lateral borders near both end plates. The height, width, and area of the vertebral canal and spinal cord in the cervical vertebra were increased as the size of dog increased. However, the ratio of the spinal cord area to vertebral canal area in the small dogs was higher than that of the larger dogs. Results of the present study could provide basic and quantitative information for CT evaluation of pathologic lesions in the cervical vertebra and spinal cord.

Cervical Intervertebral Disk to Vertebral Body Ratios of Different Dog Breeds Based on Sagittal Magnetic Resonance Imaging

“…Dog breeds were included if acceptable MRI studies (minimum of 5 animals per breed) were available for the study period. The limited number of dogs in this study ( n = 44) is similar to other comparable studies (11, 12). …”

Differences in Epidural Pathology between Cervical and Thoracolumbar Intervertebral Disk Extrusions in Dogs

“…However, they appear to be more painful than do dogs with thoracolumbar IVD extrusions . Several investigators have suggested that these observations may be a consequence of anatomic differences with respect to the size of the epidural space, presumably resulting in less severe mechanical damage to the cervical than to the thoracolumbar spinal cord …”

“…However, comparing the extent of the inflammatory response, dogs with cervical IVD extrusion displayed significantly less intense inflammation than those with thoracolumbar IVD extrusion. The larger cervical epidural space may limit tissue injury and chemical irritation by the extruded NP within the vertebral canal, consequently provoking less inflammatory reaction. Although this view remains speculative, in our previous study, we had postulated that calcified disk material may be the trigger of the inflammation.…”

“…There are substantial anatomic differences between the cervical and thoracolumbar vertebral columns, including the IVD. The vertebral canal in the cervical vertebra has a larger diameter than in the thoracolumbar vertebra, leaving more epidural space around the spinal cord . In dogs, the thoracic IVD is narrower than the cervical IVD, and the cervical IVD is nearly circular in shape when viewed craniocaudally, whereas the thoracic disks are more oval and the lumbar disks bean‐shaped .…”

“…The vertebral canal in the cervical vertebra has a larger diameter than in the thoracolumbar vertebra, leaving more epidural space around the spinal cord. 10,11 In dogs, the thoracic IVD is narrower than the cervical IVD, 12 and the cervical IVD is nearly circular in shape when viewed craniocaudally, whereas the thoracic disks are more oval and the lumbar disks bean-shaped. 12 Additionally, there are micromorphometric differences between chondrodystrophic (CD) and nonchondrodystrophic (NCD) dogs with respect to the shapes of the nucleus pulposus (NP) and anulus fibrosus (AF), and to cell densities in specific regions within the IVD.…”