A 9-year-old male neutered Boxer dog presented with chronic tetraparesis. There was mild pain on manipulation of the neck and the neurological examination localized the disease to a C6-T2 myelopathy. The dog was systemically healthy and the minimum database was normal. Cervical radiographs were also considered normal.

Atlanto-occipital CSF was considered normal. A cervical column MRI was performed.

MRI showed a bilaterally symmetrical T2W hyperintensity within the ventral gray matter of the cord at C6-C7 disc space. The intervertebral disc at this site was mildly protruding causing partial obliteration of the ventral subarachnoid space with minimum cord compression.

The bilateral intramedullary signal change

In humans, this is termed “snake-eye” myelopathy (SEM), which refers to bilaterally symmetric T2 hyperintensities preferentially affecting the ventral horn gray matter on transverse MR images, which resemble a pair of snake's eyes. The pathophysiology of SEM is poorly understood in humans, and this imaging finding may be associated with cervical spondylotic myelopathy, spinal cord ischemia, ossification of the posterior longitudinal ligament, and amyotrophic lateral sclerosis. Four dogs have been described in one report with this type of lesion which was attributed to disc-associated spinal cord compression in three cases, while one dog had the SEM-like phenotype with no identifiable etiology much like the case presented here. All 4 dogs demonstrated insidious clinical deterioration despite therapeutic interventions, also similar to this dog. The prognosis is considered poor for recovery of function.

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