Diagnosis and treatment of dynamic collapse of the cricotracheal ligament in thoroughbred racehorses

Objective To describe (1) diagnosis of dynamic collapse of the cricotracheal ligament in a group of horses and (2) treatment and outcome of affected horses. Study Design Retrospective case series. Animals Thoroughbred horses (n = 8). Methods Of 600 over ground dynamic endoscopic examinations performed, 8 Thoroughbred horses had cricotracheal ligament collapse (CTLC); 5 were 2 years old and in early training and 2 were mature horses in full work. CTLC was diagnosed if circumferential collapse of the cricotracheal ligament was identified during exercise. Seven horses had repeat endoscopic examination. Two horses unresponsive to conservative management were treated surgically. Results Multiple abnormalities of the upper portion of the respiratory tract were identified along with CTLC in all five 2-year-old horses and resolution of CTLC was observed after treatment for upper airway inflammation. No concurrent respiratory abnormality was identified in the 2 mature horses. Surgical reduction of the cricotracheal space and imbrication of the cricotracheal ligament of these 2 horses resulted in resolution of clinical signs of CTLC. Conclusions CTLC is a rare cause of dynamic obstruction in Thoroughbred racehorses. Resolution may occur after adaptation to training and after inflammation of the respiratory tract is resolved, but for horses with persistent CTLC, surgical reduction of the cricotracheal space and imbrication of the cricotracheal ligament may result in resolution of clinical signs.