Investigation of Thresholds for Asymmetry Indices to Represent the Visual Assessment of Single Limb Lameness by Expert Veterinarians on Horses Trotting in a Straight Line.
Authors: Macaire Claire, Hanne-Poujade Sandrine, De Azevedo Emeline, Denoix Jean-Marie, Coudry Virginie, Jacquet Sandrine, Bertoni Lélia, Tallaj Amélie, Audigié Fabrice, Hatrisse Chloé, Hébert Camille, Martin Pauline, Marin Frédéric, Chateau Henry
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Expert visual assessment of lameness remains the gold standard in equine practice, yet objective gait analysis systems offer increasingly precise measurements that clinicians struggle to interpret meaningfully. Researchers at CIRALE equipped 224 horses with inertial measurement unit sensors to identify specific asymmetry index thresholds that reliably correspond to expert veterinary judgement of single-limb lameness during straight-line trotting, comparing sound horses (n=49) against those with forelimb (n=129) or hindlimb (n=46) lameness. For forelimb lameness, withers-based upward amplitude asymmetry (AI-up_W) proved most reliable, with thresholds of −7% (left forelimb) and +10% (right forelimb) achieving sensitivity and specificity both exceeding 84% and 88% respectively; hindlimb lameness required pelvis-based measurements, where AI-up_P and AI-max_P thresholds of −7%/+18% and −10%/+6% respectively provided sensitivity and specificity above 78% and 82%. These quantified thresholds translate objective sensor data into clinically meaningful diagnostic criteria, enabling farriers, veterinarians and physiotherapists to standardise lameness quantification across different systems and facilities—though the authors acknowledge the relatively modest sample size warrants validation with larger datasets and investigation of horses working on circles before implementation becomes routine.
Read the full abstract on PubMed
Practical Takeaways
- •Use withers upward amplitude asymmetry thresholds (±7-10%) as objective criteria to confirm or refute suspected forelimb lameness identified on clinical examination
- •Apply pelvis-based asymmetry thresholds for hindlimb lameness detection, recognizing different threshold ranges are needed for left versus right limb involvement
- •IMU-based gait analysis systems with these validated thresholds can standardize lameness interpretation and improve diagnostic consistency across practitioners
Key Findings
- •AI-up_W (withers upward amplitude asymmetry index) discriminated forelimb lameness with thresholds of -7% (left) and +10% (right), achieving >84% sensitivity and >88% specificity
- •AI-up_P and AI-max_P discriminated hindlimb lameness with thresholds of -7% to +18% and -10% to +6% respectively, achieving >78% sensitivity and >82% specificity
- •Established asymmetry index thresholds enable objective interpretation of IMU-based gait analysis systems for lameness detection and limb localization
- •Study validates correlation between objective quantitative gait analysis data and expert veterinary visual assessment of single-limb lameness