Comparisons of overground endoscopy and treadmill endoscopy in UK Thoroughbred racehorses.
Authors: Allen K J, Franklin S H
Journal: Equine veterinary journal
Summary
# Editorial Summary: Overground versus Treadmill Endoscopy in Racehorses Whilst treadmill endoscopy has long been the standard for diagnosing upper airway dysfunction during exercise, field-based endoscopy during ridden work offers a more sport-specific alternative. Allen and Franklin's direct and indirect comparisons of both techniques in UK Thoroughbreds revealed a critical distinction: dorsal displacement of the soft palate (DDSP) was identified significantly less frequently during overground endoscopy than treadmill work, whilst dynamic laryngeal collapse showed no difference between methods. The discrepancy appears attributable to how exercise intensity is achieved—treadmill protocols employed sustained high-speed efforts at elevation, whereas field endoscopy typically involved repeated intervals at lower absolute speeds, making it difficult to replicate the consistent maximal respiratory challenge of racing conditions. This finding has important implications for clinical interpretation: a negative overground endoscopy result should not be taken as conclusive evidence of airway soundness, particularly in horses with suspected DDSP, as failure to adequately stress the upper airway during field examination may mask subclinical pathology. Practitioners should consider matching the exercise protocol to the horse's typical work demands and recognise that field-based assessment, whilst valuable for observing sport-specific mechanics, may require supplementary treadmill testing when racing conditions cannot be faithfully replicated.
Read the full abstract on PubMed
Practical Takeaways
- •When interpreting negative findings from field endoscopy (overground), ensure racing conditions have been appropriately replicated, as this technique may miss dorsal displacement of the soft palate more often than treadmill testing
- •Treadmill endoscopy may be more reliable for definitively ruling out dorsal displacement of the soft palate in racehorses with respiratory concerns
- •Both techniques appear equally valid for diagnosing dynamic laryngeal collapse, so choice can be based on availability and practical considerations
Key Findings
- •Dorsal displacement of the soft palate was diagnosed less frequently during overground endoscopy than during treadmill endoscopy in both direct (4 horses) and indirect (50 vs 50 horses) comparisons
- •No significant difference was found in the diagnosis of dynamic laryngeal collapse between overground and treadmill endoscopy techniques
- •Treadmill exercise tests were performed over longer distances at higher inclines but at lower speeds compared to overground tests
- •Overground tests were frequently performed in intervals whereas treadmill tests allowed for more sustained strenuous exercise