Magnetic Resonance Imaging Assessment of Paraspinal Muscles in Dogs with Intervertebral Disc Herniation

Abstract

A decrease in the paraspinal muscle cross-sectional area (CSA) and functional cross-sectional area (FCSA) are associated with low back pain and disc herniation in humans. This study examined whether chronicity or lateralization of disc herniation affects the CSA and FCSA of the paraspinal muscles. The CSA and FCSA of the paraspinal muscles between the 12th and 13th thoracic vertebrae were measured in 31 dogs with intervertebral disc herniation (IVDH). The muscle CSA and FCSA were evaluated by dividing the values of the body weight, spinal disc CSA, and spinal canal CSA to offset the differences in body type between subjects. In the chronic IVDH group, the ratio of the paraspinal muscle CSA divided by the body weight was significantly lower, and fat infiltration in the paraspinal muscle was significantly higher than in the acute group. The lateralization of the disc herniation was significantly related to the changes in the paraspinal muscle CSA. In the right-sided disc herniation group, right epaxial muscle CSA was significantly reduced compared to the left-sided disc herniation group. The change in the paraspinal muscle might be a helpful indicator to localize less obvious disc pathologies and target the search for the pathology responsible for disc-related symptoms in dogs.