Incidence of swallowing during exercise in horses with dorsal displacement of the soft palate.
Authors: Pigott J H, Ducharme N G, Mitchell L M, Soderholm L V, Cheetham J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Swallowing and Dorsal Displacement of the Soft Palate Dorsal displacement of the soft palate (DDSP) remains a significant cause of exercise-induced upper airway obstruction in horses, yet the mechanisms triggering collapse episodes have remained poorly understood. Pigott and colleagues used simultaneous videoendoscopic and pharyngeal pressure recordings in 42 horses with exercise-induced DDSP and matched controls to examine the relationship between swallowing behaviour and airway dysfunction during high-speed work. A striking finding emerged: affected horses demonstrated significantly increased swallowing frequency in the minute immediately before displacement occurred, whereas swallowing rates typically decrease with increasing speed in normal horses. Interestingly, this pre-displacement swallowing pattern was independent of the altered pharyngeal and tracheal pressures associated with DDSP itself—suggesting swallowing may be causally related to displacement rather than a consequence of it. For practitioners, these findings imply that DDSP may originate from neuromuscular or sensory factors rather than simple pressure dynamics alone, potentially opening new avenues for management strategies targeting the underlying drivers of palatal instability during exercise.
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Practical Takeaways
- •Increased swallowing frequency immediately before DDSP episodes may be a clinically observable precursor or indicator of impending airway collapse during exercise
- •The etiology of DDSP may be related to swallowing mechanism dysfunction rather than simple pressure dynamics, suggesting therapeutic approaches should consider swallowing physiology
- •Exercise at high speeds with acceleration appears to be the primary trigger for DDSP, which should inform training and competition management strategies
Key Findings
- •Horses with DDSP swallowed significantly more frequently in the 1 minute immediately preceding displacement compared to control horses at equivalent speeds
- •DDSP at exercise resulted in significantly increased tracheal expiratory pressure, decreased pharyngeal expiratory pressure, and less negative pharyngeal inspiratory pressure
- •Swallowing frequency decreases with increasing speed in normal horses, but increases immediately prior to DDSP onset
- •No significant difference in airway pressures before or after swallowing events in DDSP horses, suggesting pressure changes do not directly cause the increased swallowing frequency