Radiographic and computed tomographic features of a subarachnoid diverticulum causing compressive cervical myelopathy in a yearling Warmblood horse

Summary A 1‐year‐old Belgian Warmblood with a previously known history of successfully repaired temporal and parietal bone fractures sustained at 14 days of age was presented for investigation of a recent, acute and progressive quadrilateral ataxia. The owner reported a lack of coordination and difficulty getting up, with progressing paresis 2 weeks prior to the presentation. Neurological examination revealed pronounced hypermetria/dysmetria in the walk and trot in all four limbs. No evidence of cranial nerve deficits was observed. The horse was in good general condition with unremarkable clinical parameters. Survey lateral radiographs of the cervical spine revealed significant signs of cervical vertebral malformation, including hypertrophy of the articular process joints, indicating narrowing of the spinal canal with suspected cervical stenotic myelopathy. Cervical computed tomographic (CT) myelography revealed the presence of multiple dorsal subarachnoid diverticula causing significant spinal cord compression at multiple locations, with osteoarthrosis of the cervical articular process joints. Due to a poor prognosis and guarded surgical outcome, the owner declined further treatment, and the horse was discharged with conservative corticosteroid treatment. The patient was euthanised shortly after the initial presentation due to progressive worsening signs. To the authors' knowledge, CT myelography findings in a yearling with cervical subarachnoid multiple diverticula have not been previously published. This case illustrates the usefulness of advanced imaging techniques, such as CT myelography, in combination with static and dynamic radiography to provide a better and more accurate diagnosis.