Population
Medical records and high-speed treadmill endoscopy (HSTE) recordings of harness racehorses that presented with abnormal respiratory noise and/or poor performance which underwent HSTE using a standardised protocol at the Norwegian University of Life Sciences between 2005 and 2022 were reviewed. Horses were included in the study if they had videoendoscopic evidence of epiglottic compression during phases of poll flexion, prior to appearance of any other URT abnormalities (if present). Epiglottic compression was defined as inward compression of the base of the epiglottis resulting in a local U-shaped conformation which often partially or fully (visually) obscured the vocal fold(s). Data reviewed for these cases included breed, sex, age, presenting complaint and HSTE findings. Horses were excluded from the study if they were visually lame at the time of examination, diagnosed with DLC associated with poll flexion at the time of examination, if they had been diagnosed with DLC previously or if they had undergone any form of URT surgery prior to the HSTE examination.