Dr. Jon Cheetham
Dynamic airway collapse is a major cause of poor athletic function in highly performing horses. Traditionally the diagnosis of dynamic airway collapse has been made using high speed treadmill videoendoscopy but this has a number of major limitations. The overall goal of the experiments outlined in this proposal is to develop a bank of diagnostic techniques which could be performed at rest, and would predict nasopharyngeal and laryngeal dysfunction at exercise. Specifically we will: 1) Validate transesophageal ultrasound for measurement of the cross-sectional area of the sole arytenoid abductor, the cricoarytenoid dorsalis muscle, against the gold standard of muscle volume measured using computed tomography. This will be performed in sixteen Thoroughbred horses with a full spectrum of RLN disease severity (grades 1-4). (2) Determine the relationship between laryngeal position at rest and the presence or absence of DDSP at exercise in a clinical population of sixty Standardbreds and Thoroughbreds presenting for poor performance. We will measure the position of three key laryngeal anatomic landmarks using a radiographic technique developed in our laboratory and (3) use the validated technique of transesophageal ultrasound to determine the relationship between CAD muscle cross-sectional area and laryngeal function at exercise in the same clinical population presenting for poor performance.
Over two years we will have validated and tested a series of diagnostic techniques that could be performed at rest, and would predict nasopharyngeal and laryngeal dysfunction at exercise. This would extend accurate diagnosis to a wider equine population and allow more horses to receive the appropriate surgical intervention.
This work will provide invaluable data for future studies planned to test the performance of these non-invasive diagnostic tests in weanlings and yearlings with respect to their ability to predict future dysfunction at the two- and three-year-old career stages. Such a test would be invaluable to the equine industry.