Discrimination of the Lame Limb in Horses Using a Machine Learning Method (Support Vector Machine) Based on Asymmetry Indices Measured by the EQUISYM System

Abstract

Lameness detection in horses is a critical challenge in equine veterinary practice, particularly when symptoms are mild. This study aimed to develop a predictive system using a support vector machine (SVM) to identify the affected limb in horses trotting in a straight line. The system analyzed data from inertial measurement units (IMUs) placed on the horse's head, withers, and pelvis, using variables such as vertical displacement and retraction angles. A total of 287 horses were included, with 256 showing single-limb lameness and 31 classified as sound. The model achieved an overall accuracy of 86%, with the highest success rates in identifying right and left forelimb lameness. However, there were challenges in identifying sound horses, with a 54.8% accuracy rate, and misclassification between forelimb and hindlimb lameness occurred in some cases. The study highlighted the importance of specific variables, such as vertical head and withers displacement, for accurate classification. Future research should focus on refining the model, exploring deep learning methods, and reducing the number of sensors required, with the goal of integrating these systems into equestrian equipment for early detection of locomotor issues.

Keywords: horse; inertial measurement unit; lameness; machine learning; straight-line; support vector machine; symmetry.

Figure 1

Mean vertical displacement (cm) of the withers plotted against time (expressed as a percentage of stride duration) of a horse showing right forelimb (RF) lameness. Asymmetry Indices (AsI) are AsI-min = RFmin − LFmin/LFup; AsI-max = LFmax − RFmax/LFup; AsI-up = LFup − RFup/LFup; AsI-down = LFdown − RFdown/LFdown and AsI-Tmax = LFdiffTmax − RFdiffTmax/LFdiffTmax. (LF-Left Forelimb).