Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races.
Authors: Priest D T, Cheetham J, Regner A L, Mitchell L, Soderholm L V, Tamzali Y, Ducharme N G
Journal: Equine veterinary journal
Summary
# Dynamic Respiratory Endoscopy in Racing Standardbreds: What Actually Happens During Competition Understanding upper airway function during racing has remained elusive because previous diagnostic methods—treadmill examination and ridden exercise testing—cannot fully replicate competitive conditions. Priest and colleagues performed the first in-situ videoendoscopic examinations of 46 Standardbred racehorses during actual qualifying races, using portable GPS to record speed data alongside airway observations, demonstrating that the endoscope placement itself did not compromise performance. Airway obstructions were identified in 21 horses (46%), with dorsal displacement of the soft palate (DDSP) most frequently diagnosed (n=10); however, bilateral ventro-medial arytenoid displacement (VMAD) occurred during exercise as often as DDSP (n=5 each), suggesting it may be more clinically significant than previously appreciated. Notably, five DDSP cases occurred post-race rather than during competition, and horses exhibiting this post-exercise displacement demonstrated significantly slower race speeds than unaffected counterparts, raising questions about causality and the functional relevance of timing. For practitioners, these findings underscore that a negative treadmill or ridden examination does not exclude dynamic upper airway obstruction in racing conditions, whilst the emerging importance of VMAD warrants further investigation to determine whether current diagnostic and surgical protocols adequately address this condition.
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Practical Takeaways
- •Racing endoscopy is a diagnostic tool that does not interfere with horse performance and can identify airway obstructions that may not be apparent during standard training or treadmill examinations
- •Post-race airway collapse (DDSP) may be clinically relevant and worth monitoring, particularly in horses showing decreased race speed
- •VMAD during exercise appears more common than previously recognized in racing Standardbreds and should be considered in differential diagnoses for poor racing performance
Key Findings
- •Racing endoscopy was feasible and did not affect performance times compared to unexamined races (n=46 Standardbreds)
- •Airway obstructions were documented in 21 horses (45.7%), with DDSP being most common (n=10) but VMAD occurring during exercise as frequently as DDSP (n=5 each during racing)
- •Five horses with DDSP demonstrated obstruction only after the race, and these horses had significantly slower speeds during racing than unaffected horses
- •Bilateral VMAD during exercise was observed with unexpected frequency and warrants further investigation into its pathogenesis and clinical significance