Canine intervertebral disc disease: a comparative study on clinical signs, Pfirrmann MRI scores and histology in surgically treated patients

Abstract

In this retrospective study, data from 74 canine patients surgically treated for intervertebral disc herniations at the University Clinic for Companion Animals in Utrecht was evaluated. The occurrence and spinal location of type 1 and type 2 herniations in the research population, divided in chondrodystrophic (CD) and non-chondrodystrophic (NCD) breeds, was recorded. And most importantly, correlation analysis was performed on the stage of degeneration by using the grading system by Scott and McKee for neurological scores, the Pfirrmann grading system on Magnetic Resonance (MR) images, and an adjusted version of the histological scoring system by Boos et al. on surgically biopsies. Type 1 herniations had a significantly higher rate of occurrence in CD dogs compared to NCD dogs. Type 1 herniations were more common in the cervical and thoracolumbar spinal areas and type 2 herniations were found to be more common in the lumbosacral segment. No significant age difference was found between the mean ages at which dogs with either type 1 or type 2 herniations were referred to the clinic as well as between the mean ages of CD and NCD dogs. In both the Pfirrmann and the histological scoring system the scores represent the amount of disc degeneration and they did not correlate significantly with clinical symptoms. The amount of degeneration seen on MRI however does correlate with the amount of degeneration seen in the histological biopsies. In conclusion, the Pfirrmann MRI scores is significantly related to histology. MR imaging is moreover an useful imaging technique to determine the herniation localization. Future research could focus on whether MRI and histological scores can be used to predict the prognosis of IVD herniation patients. Moreover; the used population of surgical patients has many similar characteristics when compared to earlier reported characteristics of the canine population at large.