Imaging characteristics of thoracolumbar spinal stenosis due to articular process hyperplasia and degenerative joint disease in six large breed dogs.

Previous studies have reported evidence that thoracolumbar articular process hyperplasia and degenerative joint disease may be a cause of stenotic myelopathy in large breed dogs; however, detailed descriptions of imaging characteristics are currently lacking. The aim of this retrospective, multi-center, case series report was to describe imaging findings in six large breed dogs diagnosed with thoracolumbar articular process hyperplasia and degenerative joint disease causing vertebral canal stenosis. All dogs presented with progressive paraparesis, proprioceptive ataxia of the pelvic limbs, and neuroanatomical localization of T3-L3 myelopathy. All dogs underwent magnetic resonance imaging (MRI) of the thoracolumbar spine and had articular process malformations at T13-L1 (three German Shepherd dogs (GSD) and a Boxer dog) or T12-T13 (two mixed-breed dogs). Five cases were managed surgically. Findings provided more detailed imaging descriptions and supported previously published studies indicating that maldevelopment of articular processes and secondary degenerative changes can be a cause of thoracolumbar spinal stenosis and myelopathy in large breed dogs. While uncommon, this condition should be included as a differential diagnosis for large breed dogs presenting with a T3-L3 myelopathy.