New research shows that fatigue plays a key role in the displacement of the soft palate in racehorses during exercise, resulting in poor performance. As horses can breathe only through their nose, when the edges of the soft palate cover the epiglottis during exercise, called Dorsal Displacement of the Soft Palate (DDSP), the horse cannot inhale as much air as he needs to exert himself to his maximum capacity. It is believed that this condition occurs in 10 to 20 percent of horses that don't perform well.
Drs. Marta Cercone, Jonathan Cheetham, Lisa Mitchell and Norm Ducharme, of Cornell University, and Drs. Emil Olsen and Justin Perkins, of the Royal Veterinary College, implanted intramuscular electrodes into the thyro-hyoid muscles of nine racehorses that had already had their upper airway function evaluated while exercising with a scope.
Five of the horses had normal airway function and four were diagnosed as DDSP; these horses had displaced on multiple exams before the electrodes were inserted. Once inserted, the scientists recorded the electromyographic activity of the thyro-hyoid muscles during exercise tests on a treadmill.
Once the electrodes were in place, only two of the four DDSP-affected horses displaced their palate. The researchers determined that fatigue is a leading factor in exercise-induced palatal instability. They are calling for further studies to determine what muscle characteristics would predispose the muscles to fatigue.
The scientists believe that the muscles could become fatigued for a variety of reasons. Some physiological reasons muscles might fatigue include small muscles fibers or poor fiber distribution. Additionally, sub-optimal training methods could be a cause; they also offer that an overload of the muscle because of another issue, like an upper airway obstruction, may cause the muscle to fatigue. If training is at play, the scientists suggest that muscle conditioning through training may be a non-surgical option to manage DDSP.
Read more at HorseTalk.
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