title: Comparison of dynamic and resting endoscopy of the upper portion of the respiratory tract in 57 Thoroughbred yearlings.
abstract: BACKGROUND
  Endoscopic examination of Thoroughbred (TB) yearlings is performed routinely to determine the suitability of horses for racing and to ensure that the conditions of sale are satisfied. However, previous research has demonstrated that resting endoscopic examination can be inaccurate in the diagnosis of functional pathology of the upper portion of the respiratory tract (URT).
  
  
  OBJECTIVE
  To investigate the feasibility of performing dynamic overground endoscopy in a group of TB yearlings and to compare the results of resting and dynamic endoscopic examination of the URT.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Resting (pre- and post exercise) and exercising endoscopy was performed on 57 TB yearlings at a single training yard. Observed abnormalities were recorded and graded. The results of resting and dynamic examination were compared.
  
  
  RESULTS
  Dynamic overground endoscopy was well tolerated and was performed with few complications. Laryngeal asymmetry (29 cases) was the most common abnormality identified at rest, while intermittent dorsal displacement of the soft palate (IDDSP; 19 cases) was the most common at exercise. Significant variation in laryngeal function and variation in the occurrence of IDDSP was noted between examinations. Other potentially significant pathology that was not noted at rest but was present during exercise included collapse of the apex of the corniculate process, pharyngeal collapse and cricotracheal ligament collapse. The occurrence of IDDSP at exercise was significantly associated with epiglottic structure grade>2 and a recent history of respiratory tract infection.
  
  
  CONCLUSIONS
  Dynamic overground endoscopy is safe and potentially useful when assessing URT function in TB yearlings. Significant variations in the results of endoscopy at rest and during exercise were identified, which indicate that resting endoscopy may not be sufficient to predict the occurrence of pathology during exercise.
  
  
  CONCLUSIONS
  Dynamic overground endoscopic examination could be considered a suitable means of assessing URT function in TB yearlings and may provide additional pertinent information to that obtained during standard resting examination.
authors.affiliation: Weipers Centre for Equine Welfare, School of Veterinary Medicine, University of Glasgow, UK.
authors.forename: P G
authors.initials: PG
authors.lastname: Kelly
authors.forename: R J M
authors.initials: RJ
authors.lastname: Reardon
authors.forename: M S
authors.initials: MS
authors.lastname: Johnston
authors.forename: P J
authors.initials: PJ
authors.lastname: Pollock
mesh_terms: D000375:Aging; D000818:Animals; D015331:Cohort Studies; D004724:Endoscopy / Q000662:veterinary*; D006339:Heart Rate / Q000502:physiology; D006736:Horses / Q000502:physiology*; D009305:Nasopharynx / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D015619:Respiratory System Abnormalities / Q000175:diagnosis / Q000662:veterinary; D064706:Vocal Cord Dysfunction / Q000662:veterinary
keywords: Thoroughbred yearling; dynamic overground endoscopy; horse; intermittent dorsal displacement of the soft palate; laryngeal function; upper respiratory tract