Ultrasonographic assessment of the superficial digital flexor tendons of National Hunt racehorses in training over two racing seasons.
Authors: Avella C S, Ely E R, Verheyen K L P, Price J S, Wood J L N, Smith R K W
Journal: Equine veterinary journal
Summary
# Editorial Summary: Ultrasonographic Assessment of SDFT in National Hunt Racehorses Over two racing seasons, Smith and colleagues performed serial ultrasound examinations (up to six times per horse) on 263 National Hunt racehorses to establish the prevalence of superficial digital flexor tendon pathology, evaluate whether ultrasonography could predict injury, and generate reference ranges for normal tendon cross-sectional area (CSA). Ultrasonographic evidence of SDFT tendinopathy was remarkably common, affecting 24% of the cohort, though this varied substantially between training yards (10–40%), suggesting that yard-specific management and training practices may substantially influence injury risk. Notably, whilst horses presenting with existing tendinopathy were significantly more likely to sustain acute injury than those with normal ultrasonographic appearance, serial ultrasound measurements taken at three-monthly intervals failed to demonstrate any detectable changes in CSA or sonographic texture *prior* to injury occurring—meaning routine scanning alone cannot be used for predictive purposes. The study established a reference range for normal SDFT CSA of 77–139 mm² at mid-metacarpal level (station 4), with CSA remaining stable across age, limb and racing season in healthy horses, though varying according to sex and prior racing background. These findings reinforce that whilst ultrasonography remains valuable for detecting existing pathology and identifying higher-risk individuals, equine professionals require additional assessment tools—potentially incorporating biomechanical, training load and environmental factors—to meaningfully predict which horses will sustain acute SDFT injuries.
Read the full abstract on PubMed
Practical Takeaways
- •SDFT tendinopathy is common in National Hunt horses—monitor for clinical signs rather than relying on ultrasonographic screening to prevent injury
- •Substantial yard-to-yard variation in tendinopathy prevalence suggests training methods significantly influence injury risk; review your training protocols and compare with lower-injury yards
- •Use the established reference range (77-139 mm²) to identify abnormalities, but understand that baseline ultrasonography cannot reliably predict which horses will sustain acute injuries
Key Findings
- •SDFT pathology prevalence was 24% (n=148) across National Hunt racehorses, with substantial variation between yards (10-40%)
- •Routine ultrasonography at 3-month intervals failed to predict acute SDFT injuries despite detecting existing pathology
- •Horses with existing SDFT tendinopathy were significantly more likely to suffer acute injury than those with no pathology
- •Normal SDFT cross-sectional area reference range established as 77-139 mm² at level 4, with variation by sex and background but not age or limb