Instrumented cervical fusion in nine dogs with caudal cervical spondylomyelopathy

Objective: To report the long-term outcome of nine dogs treated for caudal cervical spondylomyelopathy (CCSM) with surgical spinal fusion. Study design: Short case series. Animals: Nine large-breed dogs. Methods: Medical records of dogs treated for disc-associated CCSM (2013-2016) were reviewed. The surgery objective was spinal distraction by implantation of a SynCage and fixation with two Unilock plates. Follow-up included the Helsinki pain score questionnaire, neurological grading, radiography, computed tomography (CT), and micro-CT (μCT) with subsequent histopathology (two dogs). Results: Clinical follow-up was obtained between 9 and 51 months (27.4 ± 13.4 months). The Helsinki pain score and neurological Griffith score improved (P <.01) in all dogs and in eight of nine dogs, respectively. According to CT, the volume of bone (mean ± SD) through the cage was 79.5% ± 14.3%, including compact bone (53.0% ± 23.4%). Subsidence was seen in one of nine dogs. Implant failure was evident in four dogs, and plates were removed in two dogs. In seven of nine dogs, infraclinical pathology was observed in adjacent segment, associated with implants engaging adjacent intervertebral discs. Radiographic evidence of bony fusion between vertebral bodies was noted in all dogs. Spinal fusion was confirmed by μCT and histopathology in two cervical spine segments that became available at 22 and 40 months postoperatively. Conclusion: Instrumented spinal fusion in dogs with disc-associated CCSM resulted in owner satisfaction and radiographic evidence of interbody spinal fusion in all dogs. Clinical significance: The fusion distraction technique reported here can be used to achieve spinal fusion with a good long-term outcome.