Magnetic Resonance Imaging and Neurological Findings in Dogs with Disc-Associated Cervical Spondylomyelopathy (63 cases)

Background: Canine cervical spondylomyelopathy can be separated into osseous and disc-associated (DA-CSM) forms. Our aim was to describe the magnetic resonance imaging (using a high-field scanner) and neurological findings in dogs with DA-CSM and investigate a relationship between these findings.Results: Sixty-three dogs were included: 60/63 (95%) were large breeds, with Doberman Pinschers and males over-represented (70%). Mean and median age at the time of diagnosis was 7.25 and 7.2 years (range 0.41 – 12 years). Chronic signs were noted in 52/63 (83%) dogs, with proprioceptive ataxia the most common. Main site of spinal cord compression was commonly C6-C7 or C5-C6. Thirty-six (57%) dogs had various sites of spinal cord compression. Most dogs younger than 6 years of age had a single affected. Foraminal stenosis was present in 51/63 dogs (81%). T2-weighted hyperintensity was present in 40/63 dogs (63%). Eighty-eight percent of the articular processes showed degenerative changes, which correlated strongly with intervertebral disc degeneration. Ligamentum flavum hypertrophy was seen in 38% of dogs. No correlation was observed between neurologic signs and number of affected sites. A moderate positive correlation was observed between severity of spinal cord compression and neurologic grade (r 0.48; p<0.001).Conclusions: DA-CSM was predominantly observed in older, male Dobermans, with chronic neurologic signs, with compressive lesions located in the caudal cervical vertebral region. Although less common, DA-CSM was also seen in dogs 3 years of age or younger (8%). Single compressive lesions were more common in dogs younger than 6 years of age. Most dogs had concomitant changes (e.g.: ligamentum flavum hypertrophy and foraminal stenosis) that may affect neurologic signs. Most dogs with ligamentum flavum hypertrophy were 6 years or older. A correlation was observed between severity of spinal cord compression and neurologic grade; dogs with more severe spinal cord compression were more likely to have a higher neurologic grade. Dogs with more sites of spinal cord compression did not have more severe neurologic involvement. A very high percentage of dogs had articular process degenerative changes. Possible biomechanical or genetic relationships between degenerative changes in articular processes, ligamentum flavum, and intervertebral discs warrants further investigation.