Abstract
BackgroundIn equine athletes, dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance. There are hypotheses, that head and neck flexion may influence the morphology and function of the upper airway and thus could even induce or deteriorate disorders of the upper respiratory tract. Especially the pharynx, without osseous or cartilaginous support is prone to changes in pressure and airflow during exercise. The objective of this study was to develop a method for measuring the pharyngeal diameter in horses during exercise, in order to analyse whether a change of head-neck position may have an impact on the pharyngeal diameter.ResultsUnder the assumption that the width of the epiglottis remains constant in healthy horses, the newly developed method for calculating the pharyngeal diameter in horses during exercise is unsusceptible against changes of the viewing-angle and distance between the endoscope and the structures, which are to be assessed. The quotient of the width of the epiglottis and the perpendicular from a fixed point on the dorsal pharynx to the epiglottis could be used to determine the pharyngeal diameter. The percentage change of this quotient (pharynx-epiglottis-ratio; PE-ratio) in the unrestrained head-neck position against the reference position was significantly larger than that of any other combination of the head-neck positions investigated. A relation between the percentage change in PE-ratio and the degree of head and neck flexion could not be confirmed.ConclusionsIt could be shown, that the pharyngeal diameter is reduced through the contact position implemented by the rider in comparison to the unrestrained head and neck position. An alteration of the pharyngeal diameter depending on the degree of head and neck flexion (represented by ground and withers angle) could not be confirmed.
Highlights
In equine athletes, dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance
In two of the horses examined, the measured Ground angle (GA) and/or Withers angle (WA) in all head positions analysed varied above the predetermined limit of standard deviation
Under the assumption that the width of the epiglottis remains constant, the present study provides a method to assess dimensions of the upper airway independently of the viewing-angle and distance between the scope and the relevant structures
Summary
Dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance. The pharynx, without osseous or cartilaginous support is prone to changes in pressure and airflow during exercise. The objective of this study was to develop a method for measuring the pharyngeal diameter in horses during exercise, in order to analyse whether a change of head-neck position may have an impact on the pharyngeal diameter. Due to its musculomembraneous structure without osseous or cartilaginous support, the pharynx in particular is prone to changes in pressure and airflow during exercise [3]. The aim of the present study was to examine the effects of four different contact positions on pharyngeal width in horses and, with the aid of a new method of measurement, to assess whether a change in pharyngeal diameter dependent on head-neck position can be confirmed
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