Atlanto-occipital subluxation in an adult Thoroughbred gelding

Abstract

A 13-year-old gelding was referred to the University of Liverpool Equine Hospital for further investigation of ataxia and neck pain following a suspected traumatic incident in the field 5 days prior. The following case report documents the clinical presentation, ultrasonographic, radiographic and computed tomographic (CT) findings of a right lateral atlanto-occipital (AO) subluxation. In brief, clinical presentation included abnormal head carriage, ataxia and cranial cervical swelling with associated neck pain. Radiography showed lateral deviation of the poll and subluxation of the right AO joint with significant widening of the left AO joint. CT was undertaken standing which confirmed lateral luxation of the right occipital condyle in relation to the right articular process of the AO joint such that the right articular process of the atlas was located medial to the right occipital condyle. The gelding was subjected to euthanasia and post-mortem the subluxation was resolved with a closed traction procedure. This case initiates discussion of diagnosis, management and outcome for this uncommon injury. The use of CT in this case gives previously undocumented detail on the nature of the subluxation and assisted in the management and post-mortem closed reduction procedure.