Exercising upper respiratory videoendoscopic findings of 50 competition draught horses with abnormal respiratory noise and/or poor performance.

Background: Upper respiratory tract (URT) endoscopy at rest is commonly used to evaluate competition draught horses with URT conditions. Overground endoscopy might be preferred for draught horse URT evaluation as it allows the horses to be driven with harness, overcheck and cart-load under similar conditions to those experienced in the show ring where airway conditions are most prominent.
Objective: To describe the exercising URT findings of competition draught horses with abnormal respiratory noise and/or poor performance.
Study Design: Case series.
Methods: Medical records of competition draught horses undergoing overground endoscopic evaluation between January 2013 and January 2018 with a presenting complaint of abnormal respiratory noise and/or poor performance were reviewed. Video recordings of resting and overground endoscopy were evaluated in all horses. Spearman's rank correlation coefficient was calculated between laryngeal function at rest and at exercise.
Results: Fifty competition draught horses were examined. Thirteen had previously undergone URT surgery. There was significant correlation between resting and exercising laryngeal function (ρ = 0.77, P<0.01). Abnormalities were detected in 46 horses and included arytenoid cartilage collapse (n = 31), vocal fold collapse (n = 27), palatal dysfunction (n = 14), epiglottic disorders (n = 11), dynamic laryngeal collapse (n = 1), rostral deviation of the palatopharyngeal arch (n = 3) and medial deviation of the aryepiglottic folds (n = 16). The majority of horses had a complex of abnormalities (n = 31) or required exercising examination for identification (n = 41). Incidental upper oesophageal incompetence was observed in nine horses.
Main Limitations: Retrospective collection of data.
Conclusions: Overground endoscopic evaluation was a useful technique for identifying URT disorders in competition draught horses. The spectrum of upper airway conditions identified in exercising draught horses supports the use of overground endoscopy as a diagnostic technique and could influence treatment considerations. The Summary is available in Portuguese - see Supporting Information.
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