Right subclavian artery anomaly in an adult Friesian horse

This report describes an unusual vascular ring anomaly (VRA) that resulted in repeated oesophageal obstruction in an adult horse. Oesophagoscopy identified a luminal obstruction with secondary mucosal sloughing. Post mortem findings revealed oesophageal and tracheal stenosis secondary to an aberrant right subclavian artery. The presence of the VRA may have resulted in repeated oesophageal impactions in an adult horse and the hereditary potential for this defect should be considered.