The Computed Tomographic Appearance of Acute Thoracolumbar Intervertebral Disc Herniations in Dogs

Abstract

The appearance of herniated intervertebral disc material in the thoracolumbar 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 hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments 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 hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.

Usefulness of Myelography with Multiple Views in Diagnosis of Circumferential Location of Disc Material in Dogs with Thoracolumbar Intervertebral Disc Herniation

“…Therefore, the determination of the surgery sites should not rely on survey radiography. Computed tomography (CT) and magnetic resonance imaging (MRI) has become more widely available to veterinary medicine recently and can provide useful information in the diagnosis of the intervertebral disc herniation [3,13,14]. Postmyelographic CT or MRI may be useful, if the origins and locations of the compressing lesion cannot be readily detected on myelography.…”

Effect of Anesthesia, Positioning, Time, and Feeding on the Proventriculus: Keel Ratio of Clinically Healthy Parrots

“…1 All dogs with spinal cord swelling evident on myelographic imaging were plegic, suggesting that this category should preferably undergo CT myelography to permit correct lesion characterization, localization and lateralization, while simultaneously evaluating for spinal cord swelling. Importantly, we demonstrated nondisc disease as a cause of acute myelopathy in a low number of chondrodystrophic cases: extradural hemorrhage of unknown origin, correctly diagnosed from survey CT 9 and confirmed at necropsy, and subarachnoid cyst diagnosed from myelographic imaging, confirmed at surgery. Furthermore, the inclusion of all etiologies permitted our study to reaffirm that conventional CT had low sensitivity for clinically significant but poorly mineralized Hansen Type I disc extrusions and nonmineralized Hansen type II disc protrusions and that intramedullary lesions such as meningomyelitis and spinal cord infarction may not be conspicuous on myelography, CT, or CT myelography.…”

“…While there are retrospective studies, 9,10,14,15 there are no prospective studies comparing multiple signalments, etiologies, and imaging modalities of acute canine myelopathies. The purposes of this study were: (1) to determine prospectively the sensitivity for conventional CT, angiographic CT, CT myelography, and conventional myelography for the diagnosis of acute spinal cord disease, (2) to identify the limitations of each imaging technique for diagnosis of acute myelopathies, and (3) to make recommendations for the selection of imaging modality when investigating acute myelopathies, without compromising sensitivity.…”

Using geographical information system for spatial evaluation of canine extruded disc herniation

“…Every EDH was identified and recorded according to position and location including single (protrusion of only one intervertebral disc) or multiple patterns (protrusion of more than one intervertebral disc in the same dog). The diagnosis of Hansen type I disc herniation was made on the basis of characteristics described above and in more detail by Olby et al (2000) and Lim et al (2010).…”