Radiography, CT ‐angiography and post‐mortem findings in a foal with a congenital type 3 vascular ring anomaly

Summary Congenital vascular ring anomalies (VRA) have been occasionally described in horses. To the authors' knowledge, this is the first case report providing radiographic and computed tomography (CT) findings of a congenital type 3 persistent right aortic arch (PRAA) in a foal. A 1.5 months old Franches‐Montagnes colt was presented for growth retardation with a history of mild intermittent bilateral nasal discharge occasionally containing milk and coughing since birth. Thoracic radiographs and ultrasound, oesophagoscopy, positive contrast oesophagography and CT angiography were performed. A final diagnosis of persistent right fourth aortic arch, with left ligamentum arteriosum and aberrant left subclavian artery (type 3 VRA) and subsequent aspiration pneumonia was achieved. Due to the poor physical condition, the presence of severe aspiration pneumonia and most importantly the lack of a surgical option for a type 3 VRA, the colt was euthanised and the post‐mortem examination confirmed the oesophagography and CT angiography findings.