Equine lameness detection and monitoring during diagnostic anaesthesia with an instrumented hoof boot

Ground reaction forces are accepted as gold standard for objective assessment of weightbearing lameness but measurements at the hoof are limited to experimental devices. This study aimed to evaluate whether innovative instrumented hoof boots (IHBs) could detect and monitor lameness in horses during diagnostic anaesthesia. Twenty-six horses referred for lameness examination (15 frontlimbs, 17 hindlimbs) were equipped with IHBs and body mounted inertial sensors. Data were collected simultaneously before and after diagnostic anaesthesia until objectively considered positive. Recorded IHB data included median values of peak vertical pressure [N] (PVP), impulse [Ns] (AUC), peak loading rate [N/ms] (PLR) and further force and temporal parameters. Absolute and relative differences were compared before and after anaesthesia. Bonferroni-Holm method and Wilcoxon signed-rank test were used for statistical analysis (α=5%). Mean PVP and AUC of lame and contralateral limbs differed significantly before positive diagnostic anaesthesia data (p<0.001, p<0.001) and not after (p=0.074, p=0.196) in the overall data. The PLR differed significantly before and after anaesthesia (p=0.006, p=0.024). Overall mean PVP and AUC difference between lame and contralateral limbs differed significantly (p=0.015, p=0.001) between baseline lameness (PVP 3.54%, AUC 5.44%) and not after anaesthesia (PVP 0.90%, AUC 2.04%), respectively. Non-significant differences were seen in further study parameters. Main limitations were a small, mixed-breed population, unknown horse speed and different diagnoses. This study shows that the IHB was generally suitable for detection of differences between lame and contralateral limbs and to evaluate the effect of positive diagnostic anaesthesia by showing a more symmetrical distribution of PVP and AUC between contralateral limbs after improvement of lameness.