Comparison of Asymmetry During Trot In-Hand With Evaluations of Discomfort and Pain in Horses While Exercised.
Authors: Soiluva Johanna, Häyrinen Lotta, Gangini Giacomo, Öistämö Ruut, Gracia-Calvo Luis Alfonso, Raekallio Marja Riitta
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Objective lameness assessment remains challenging in equine practice, with traditional visual evaluation prone to observer bias and subjective interpretation. Researchers compared three assessment approaches—visual lameness scoring and behavioural observation during ridden exercise, inertial sensor measurement of movement asymmetry during trot in-hand, and cardiac biomarkers (heart rate and heart rate variability)—in 30 horses to determine whether these tools provide complementary information about pain and discomfort. Using a 10 mm asymmetry threshold, the sensor system classified 25 of 30 horses as lame, yet found no significant differences between the "lame" and "sound" groups across subjective lameness scores, behavioural ethograms, or resting cardiac metrics—a surprising result that calls into question either the sensor threshold or the sensitivity of visual assessment in detecting subtle gait deficits. Notably, movement asymmetry measured in-hand correlated significantly with heart rate and heart rate variability during ridden work at higher intensities, suggesting that quantifiable gait asymmetry does reflect physiological stress responses when horses are exercised, even if visual observers fail to detect lameness consistently. These findings warrant careful recalibration of sensor thresholds and suggest that combining objective gait analysis with cardiac monitoring during ridden exercise may offer practitioners a more nuanced understanding of subclinical discomfort—particularly valuable for performance horses where early detection of biomechanical asymmetry could inform intervention before overt lameness develops.
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Practical Takeaways
- •Objective sensor systems for detecting gait asymmetry may identify subclinical lameness earlier than visual assessment alone, but the clinical significance of small asymmetries (under 10mm) remains unclear and warrants field validation
- •When horses show gait asymmetry during in-hand trot, expect increased physiological stress indicators (elevated HRV) during ridden exercise—consider this when determining soundness for work
- •Don't rely on single assessment methods; combine subjective lameness scoring, behavioral observation, and objective sensor data for more complete lameness evaluation, as these measures assess different aspects of equine health
Key Findings
- •Inertial sensor system detected 25 of 30 horses (83%) as lame using a 10mm asymmetry threshold, while subjective lameness scores and ethograms showed no significant differences between sound and lame groups
- •Gait asymmetry and heart rate variability (RMSSD) correlated significantly during certain phases of ridden exercise, suggesting sensor-detected asymmetry relates to pain response at intensity
- •Traditional visual lameness assessment, behavioral ethograms, and heart rate showed poor correlation with objective sensor-measured movement asymmetry
- •The current 10mm asymmetry threshold for lameness detection by inertial sensors may be overly sensitive and requires further validation