Clinical outcome after tracheal resection and anastomosis for correction of a tracheal stenosis in a sport pony

Introduction: Tracheal stenosis, which refers to a narrowing of the tracheal lumen, is infrequent in horses. The literature is scarce about outcome after treatment of this pathology.
Objectives: To report our experience using tracheal resection and anastomosis to treat a severe trauma-induced tracheal stenosis (< 1 cm diameter of lumen) involving 2 tracheal rings causing a loud respiratory noise at rest in a 14 y.o. event pony.
Methods: The pony was trained to wear a martingale preoperatively. Before the surgery, a distal tracheotomy was performed for placement of the tracheal tube for maintenance of gaseous anaesthesia. Through a 35 cm ventral midline cervical incision, the trachea was exposed and separated from adjacent tissues. Stay sutures were placed in tracheal cartilage adjacent to the segment to be removed. The 2 tracheal rings involved in the stricture were subsequently removed. On both remaining segments of the trachea, the mucosa was turned back over the open end and sutured to the adventitia. The head was then flexed and tracheal ends were apposed using 5 stainless steel wires placed equidistantly around the trachea without mucosal penetration. The anastomosis was completed by a simple continuous suture of resorbable material on the adventitia. A closed suction drain was applied in the soft tissue before routine closure of the subcutaneous and cutaneous layers. The martingale was applied before the recovery from anaesthesia, which was uneventful. The tracheotomy tube and the suction drain were left in place for 48h. The martingale was removed after 3 weeks. The pony was discharged 1 month after surgery. Control endoscopies were performed during hospitalisation and at 7, 10, 17, 21 and 30 weeks and 1 year after surgery.
Results: A moderate cicatrix recurred. The excessive tissue was injected with triamcinolone and then with 4% formaldehyde during the first endoscopies and remained stable thereafter. Some stainless steel cerclages broke and displaced slightly. This caused the formation of a self-resolving seroma caudally to the trachea. A moderate respiratory noise was still audible at low-intensity work, which was resumed 4 months postoperatively. However, work was stopped before achieving the preoperative level because the pony developed a lameness.
Conclusions: Although a moderate tracheal cicatrix recurred after surgery, tracheal resection and anastomosis clearly improved the quality of life of this pony.