Cricothyroid muscle function and vocal fold stability in exercising horses

Area of Science:

• Equine respiratory physiology
• Equine upper airway function

Background:

• The cricothyroid muscle plays a role in laryngeal function during respiration.
• Understanding laryngeal dynamics is crucial for equine athletic performance.

Purpose of the Study:

• To investigate the electromyographic (EMG) activity of the cricothyroid muscle during exercise in horses.
• To assess the impact of bilateral cricothyroid myotomy on vocal fold stability and airway pressures during exercise.

Main Methods:

• Experimental study involving treadmill exercise in Standardbred horses.
• Electromyography of the cricothyroid muscle and measurement of nasopharyngeal pressures.
• Videoendoscopic examination before and after bilateral cricothyroid myotomy.

Main Results:

• Cricothyroid muscle EMG activity increased with inspiratory effort and treadmill speed.
• Bilateral cricothyroid myotomy induced vocal fold collapse in all treated horses.
• Significantly more negative inspiratory pressures were recorded post-myotomy.

Conclusions:

• Cricothyroid muscle dysfunction is linked to vocal fold collapse in exercising horses.
• Compromised cricothyroid muscle function or innervation may cause inspiratory airway obstruction.