The volume of extruded materials is correlated with neurologic severity in small-breed dogs with type I thoracolumbar intervertebral disk herniation.

Abstract

OBJECTIVE: To assess whether the volume of extruded materials is correlated with neurologic severity in dogs with type I thoracolumbar intervertebral disk herniation (TL-IVDH). ANIMALS: 70 client-owned small-breed dogs with type I TL-IVDH diagnosed between July 1, 2016, and June 30, 2018. PROCEDURES: For this retrospective cohort study, the medical records of 70 dogs with surgically confirmed type I TL-IVDH were reviewed. The volume and height of the intervertebral disk and the area of the maximal transverse compressed spinal cord were measured using CT myelographic images. For each dog, the volume of the disk immediately cranial to the herniated disk was an internal control. Dogs were grouped on the basis of grade of neurologic severity. RESULTS: Preoperative grades of neurologic severity were grade 2 in 7 (10%) dogs, grade 3 in 16 (23%) dogs, grade 4 in 28 (40%) dogs, and grade 5 in 19 (27%) dogs. The total volume of the affected intervertebral disks was significantly larger than the internal control. Weak positive correlation was found between the volume of the extruded materials into the vertebral canal and the grade of neurologic severity. CLINICAL RELEVANCE: Our findings indicated that the total volume of the affected intervertebral disks is larger in dogs with type I TL-IVDH, and the volume of the extruded materials into the vertebral canal is weakly correlated with the neurologic severity.