Atlanto-occipital luxation is considered rare in both humans and animals. Lateral radiographs are recommended for diagnosis, however, errors may occur related to the angle of radiation, image target, distance and overlapping of bone. Our objective is to report the clinical and radiographic findings in two dogs with traumatic atlanto-occipital luxation, which had tetraparesis, cranial neck pain, and inability to raise the head and cranial nerve deficits. The first animal had a cranio-dorsal dislocation of the articular process of the atlas in relation to one of the occipital condoles, with no overlapping of the transverse foramens or overlapping of the occipital condile in relation to the articular process of the atlas, on the right side, which characterizes a unilateral luxation. The second animal presented with a cranio-caudal dislocation of the articular processes of the atlas regarding the occipital condoles, with overlapping of the transverse foramens and inability to visualize the occipital condoles due to the cranial advancement of the articular processes of the atlas towards the skull, which characterizes a bilateral luxation. We conclude that a simple radiographic exam, in lateral and ventrodorsal projections, though difficult to interpret, is efficient in confirming a diagnosis of traumatic atlanto-occipital luxation, both symmetric and asymmetric.
craniocervical junction; luxation; radiodiagnostic criteria
