Bilateral dynamic laryngeal collapse associated with collection in 'high poll flexion' in a gaited Icelandic horse.

摘要

A 6-year old female Icelandic Horse was evaluated because of marked respiratory noise and distress at the tolling gait. Resting endoscopy and high speed treadmill videoendoscopy at trot and gallop did not reveal any significant abnormalities, but it was not possible to urge the horse into the tolting gait on the treadmill by using long reins. It was however possible to ride the horse on the treadmill and when tolling, an abnormal respiratory noise was immediately noticed. Videoendoscopy revealed marked bilateral vocal fold and arytenoid cartilage collapse (bilateral dynamic laryngeal collapse) that disappeared when the horse was allowed to lower its head carriage and trot or gallop. The condition was consistently and easily reproduced when the horse was urged back into the tolting gait. The horse was intended for gaited competitions, bilateral ventriculocordectomy was therefore attempted in hopes of restoring some degree of performance. The mare was able to compete thereafter, but a mild degree of respiratory noise was still audible when ridden at the tolting gait. Bilateral dynamic laryngeal collapse associated with poll flexion has previously only been described in harness racehorses. In this case the syndrome was only apparent while the horse was tolting and seemed related to periods of collection in "high poll flexion". This case underscores the importance of accurately reproducing the conditions that provoke the clinical disorders in order to arrive at a correct diagnosis.