Clinical and imaging findings in dogs with nerve root signature associated with cervical intervertebral disc herniation

Abstract

Background: Intervertebral disc herniation (IVDH) is the most common spinal cord disease in dogs. Little information is available regarding the clinical presentation of nerve root signature (NRS) associated with cervical IVDH.

Hypothesis/objective: To detail the clinical and magnetic resonance imaging (MRI) findings in dogs with NRS associated with cervical IVDH.

Animals: Forty-seven client-owned dogs presenting with thoracic limb NRS and MRI confirmed IVDH.

Methods: Medical records from 2010 to 2020 were retrospectively reviewed for dogs that met inclusion criteria. Imaging studies were evaluated by 2 individuals to characterize location and severity of neural tissue compression.

Results: Chondrodystrophoid dogs comprised the majority of the study cohort, with dachshund the most common breed (n = 10). Three-quarters of dogs were ≥7 years of age. Interobserver agreement was moderate or good for all of the imaging variables evaluated. The C6-C7 intervertebral disc space was significantly overrepresented (P = .01), comprising 32% (15/47) of the affected discs. However, 42% (20/47) of cases involved C2-C3 though C4-C5 disc sites. Disc material was more frequently located laterally compared to medially within the vertebral canal (P = .0005), and to be associated with compression of the nerve root at the level of the intervertebral foramen (P = .012).

Conclusion/clinical importance: NRS is most commonly associated with lateralized or foraminal cervical disc herniations. It is most prevalent with C6-C7 intervertebral disc involvement, suggesting that there might be unique anatomic factors that contribute to development of NRS at this site, but can be a clinical manifestation of IVDH occurring anywhere along the cervical spine.

Keywords: cervical radiculopathy; intraforaminal disc herniation; magnetic resonance imaging; thoracic limb lameness.