The computed tomographic appearance of acute thoracolumbar intervertebral disc herniations in dogs

The appearance of herniated intervertebral disc material in the thoracolumb ar vertebral canal was evaluated in 23 dogs using computed tomography (CT), The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenua ting extradural mass. The attenuation of the disc material increased with t he degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragm ents of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hy perattenuating and homogeneous appearance than recently herniated disc mate rial, We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.