Dynamic Laryngeal Collapse Associated with Poll Flexion

Dynamic laryngeal collapse (DLC) associated with poll flexion defined as bilateral vocal fold (VF) collapse with some degree of concurrent bilateral arytenoid cartilage (AC) collapse is a newly described dynamic upper respiratory tract (URT ) obstructive disorder diagnosed most frequently to date in Norwegian Coldblooded Trotters (NCT).1,2 Often accompanied by other URT abnormalities including dorsomedial deviation of the epiglottic margins and/or aryepiglottic folds,1,2 this disorder is associated with head carriage. Complaints of abnormal URT noise and poor performance are associated with periods of poll flexion during training and racing. Although harness racehorses are encouraged to race with an extended head and neck position, poll flexion occurs when horses are restrained onto the bit to prevent premature exhaustion during races.1 NCT horses seemingly have an exaggerated racing will that necessitates restraint by the driver, which appears to predispose to this obstructive disorder.1 Diagnosis can only be made by high speed treadmill videoendoscopy (HSTV) with periods of induced poll flexion, which is achieved by examining horses with full head gear, including head check rein, and driving them on the treadmill with long reins.  […]