Magnetic resonance imaging and neurologic characterization of combined osseous- and disc-associated cervical spondylomyelopathy in dogs.

Background: Although both disc- or osseous-associated forms of cervical spondylomyelopathy (CSM) are observed in the same dogs, this combined form has not been thoroughly evaluated.

Objectives: To describe imaging characteristics of dogs with concurrent disc- and osseous CSM and investigate an association between findings on neurological examination and imaging.

Animals: Sixty dogs with disc and osseous-associated CSM from 232 CSM-affected dogs.

Methods: Retrospective study. Dogs diagnosed via high-field MRI with a combination of intervertebral disc (IVD) protrusion and osseous proliferation of articular processes, dorsal lamina, or both were identified. Large and giant breed dogs were grouped according to whether combined compressions were at the same site or different sites. Statistical methods were used to investigate the association and relationship between variables.

Results: Thirty-five out of 60 (58%) were large breeds and 22/60 (37%) were giant breeds. Mean and median age was 6.6 and 7 years respectively (range, 0.75-11 years). Forty of the 60 dogs (67%) had concurrent osseous and disc-associated spinal cord compression in the same location. This was considered the main compression site in 32/40 (80%) dogs. Dogs with osseous- and disc-associated compressions at the same site were more likely to have a higher neurologic grade (P = .04).

Conclusions And Clinical Importance: A substantial percentage of dogs with CSM present with concomitant IVD protrusion and osseous proliferations, most at the same site. Characterizing this combined form is important in the management of dogs with CSM because it could affect treatment choices.