## Overview Atlanto-axial subluxation is partial dislocation of the joint between the first cervical vertebra (atlas) and the second cervical vertebra (axis). It may be congenital or, more often in adults, the result of trauma that disrupts the ligaments stabilizing the dens. The subluxation can compress the spinal cord, producing ataxia or neck pain and stiffness. True luxation (complete dislocation) is rarer and more severe. ## Causes Trauma from falls, rearing and falling backward, or collisions is the usual cause in mature horses. Congenital forms exist but are less commonly reported than occipitoatlantoaxial malformation. Ligamentous failure allows ventral or lateral displacement of the axis relative to the atlas. ## Diagnosis Clinical signs include neck stiffness, abnormal head carriage, reluctance to flex or extend the neck, and variable ataxia. Radiographs demonstrate malalignment; standing computed tomography provides superior detail of the dens and articular relationships. Neurologic examination quantifies spinal-cord compromise. ## Treatment Mild, stable subluxations may be managed with stall rest and anti-inflammatory medication. Unstable or significantly displaced cases require surgical reduction and stabilization when feasible. Closed reduction under general anesthesia has been successful in selected adult horses. ## Recovery and Prognosis Prognosis depends on the degree of spinal-cord compression and the stability achieved. Horses with minimal neurologic deficits and successful reduction can return to work. Severe cord damage or irreducible instability carries a guarded to poor prognosis. ## Prevention No specific prevention beyond minimizing traumatic incidents.
neck pain or stiffness; abnormal head carriage; reluctance to move the neck; ataxia; audible click in some cases
## Overview Atlanto-axial subluxation is partial dislocation of the joint between the first cervical vertebra (atlas) and the second cervical vertebra (axis). It may be congenital or, more often in adults, the result of trauma that disrupts the ligaments stabilizing the dens. The subluxation can compress the spinal cord, producing ataxia or neck pain and stiffness. True luxation (complete dislocation) is rarer and more severe. ## Causes Trauma from falls, rearing and falling backward, or collisions is the usual cause in mature horses. Congenital forms exist but are less commonly reported than occipitoatlantoaxial malformation. Ligamentous failure allows ventral or lateral displacement of the axis relative to the atlas. ## Diagnosis Clinical signs include neck stiffness, abnormal head carriage, reluctance to flex or extend the neck, and variable ataxia. Radiographs demonstrate malalignment; standing computed tomography provides superior detail of the dens and articular relationships. Neurologic examination quantifies spinal-cord compromise. ## Treatment Mild, stable subluxations may be managed with stall rest and anti-inflammatory medication. Unstable or significantly displaced cases require surgical reduction and stabilization when feasible. Closed reduction under general anesthesia has been successful in selected adult horses. ## Recovery and Prognosis Prognosis depends on the degree of spinal-cord compression and the stability achieved. Horses with minimal neurologic deficits and successful reduction can return to work. Severe cord damage or irreducible instability carries a guarded to poor prognosis. ## Prevention No specific prevention beyond minimizing traumatic incidents.
neck pain or stiffness; abnormal head carriage; reluctance to move the neck; ataxia; audible click in some cases