Imaging findings for Atlanto-occipital assimilation with multiple cervical vertebral anomalies in a Beagle dog: A 2 year follow-up

Abstract

A 3-year-old male Beagle dog was presented for a physical examination, which revealed a mild stiff neck that was affecting movement. The imaging modalities led to our diagnosis of an asymmetric fusion of the occipital condyle and atlas wing consistent with Atlanto-occipital assimilation (AOA). An incomplete ossification of the atlas and axis, dysplastic dens, and a blocked vertebra were also noted. During a two-year follow-up, the dog showed no other clinical signs or disease progression. To our knowledge, this is the first imaging description of AOA in veterinary medicine. We recommend a careful CT (computed tomography) and an MRI (magnetic resonance imaging) evaluation in cases of neck pain and cervical myelopathy, and inclusion of AOA among the differential diagnoses, with the awareness that its clinical signs resemble those of other canine diseases.

Keywords

• atlanto-occipital assimilation
• atlanto-occipital fusion
• atlas occipitalisation
• cervical vertebral anomaly
• dog