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

Overview

• This study investigates the use of innovative instrumented hoof boots (IHBs) to detect and monitor equine lameness during diagnostic anaesthesia, comparing their measurements to standard inertial sensors.
• It finds that IHBs can effectively measure changes in weightbearing and pressure on limbs, showing more symmetry between lame and sound limbs after anaesthesia, which indicates improvement in lameness.

Introduction and Background

• Equine lameness, a condition where a horse shows impaired limb function, is commonly assessed by measuring ground reaction forces during weightbearing.
• Ground reaction forces are considered the gold standard for objective lameness assessment but typically require experimental or specialized equipment placed at the hoof.
• Previous methods for measuring forces directly at the hoof have been limited, and there is a need for practical, non-invasive devices usable in clinical settings.

Purpose of the Study

• The study aims to evaluate whether instrumented hoof boots (IHBs) can detect and monitor lameness during diagnostic anaesthesia in horses.
• Diagnostic anaesthesia temporarily numbs specific areas, allowing veterinarians to identify the source of lameness by observing if symptoms improve.
• The hypothesis is that IHBs can record force and pressure data showing differences between lame and contralateral (opposite) limbs before anaesthesia and reveal improved symmetry after anaesthesia.

Methods

• Participants:
  • 26 horses referred for lameness examination were studied.
  • Lameness involved 15 front limbs and 17 hind limbs.
• Equipment:
  • Horses wore instrumented hoof boots to measure ground reaction forces at the hoof.
  • Body-mounted inertial sensors were also used as a comparison to measure motion and lameness.
• Data Collection:
  • Data were collected simultaneously from the boots and sensors before and after the application of diagnostic anaesthesia, stopping data collection once a positive anaesthetic response was observed.
  • Parameters recorded by the IHB included:
    • Median peak vertical pressure (PVP) in Newtons (N)
    • Impulse (area under the curve, AUC) in Newton-seconds (Ns)
    • Peak loading rate (PLR) in Newtons per millisecond (N/ms)
    • Other force and timing-related parameters
• Statistical Analysis:
  • Differences in measurements between lame and contralateral limbs before and after anaesthesia were analyzed using Wilcoxon signed-rank test.
  • Bonferroni-Holm correction was applied to adjust for multiple comparisons.
  • Significance level was set at α = 5%.

Results

• Before anaesthesia, there were significant differences between lame and contralateral limbs for:
  • Peak vertical pressure (PVP): p < 0.001
  • Impulse (AUC): p < 0.001
• After anaesthesia, differences in PVP and AUC between limbs were not significant:
  • PVP: p = 0.074
  • AUC: p = 0.196
• Peak loading rate (PLR) showed significant differences both before (p = 0.006) and after anaesthesia (p = 0.024), suggesting it may capture subtle changes.
• Overall median differences in PVP and AUC between lame and contralateral limbs decreased significantly after anaesthesia:
  • Before anaesthesia: PVP difference ~3.54%, AUC difference ~6.47%
  • After anaesthesia: PVP difference ~0.90%, AUC difference ~2.04%
• Other force and temporal parameters did not show statistically significant differences.

Discussion and Interpretation

• The IHB successfully detected and quantitatively measured the asymmetry between lame and sound limbs in horses.
• After diagnostic anaesthesia, which should reduce lameness if the correct site is numbed, the increase in symmetry of PVP and AUC indicates that the device can monitor treatment effect.
• Peak loading rate data suggest some sensitivity to changes due to anaesthesia, but results were mixed.
• Other parameters may require further research or larger sample sizes for validation.
• The combination with body-mounted inertial sensors strengthens the objective assessment of lameness and its improvement.

Limitations

• Small and diverse sample size (only 26 horses, various breeds and diagnoses) limits generalizability.
• Speed of horses during data collection was not controlled or known, which could affect force measurement consistency.
• Different underlying causes of lameness among horses could impact force patterns and responses.

Conclusions

• The instrumented hoof boot shows promise as a practical and objective tool for detecting lameness and monitoring the effect of diagnostic anaesthesia in horses.
• By demonstrating more symmetrical force distribution between limbs after anaesthetic intervention, it aids veterinarians in confirming the source of lameness and treatment effectiveness.
• This technology could complement existing diagnostic procedures and potentially improve clinical lameness evaluations.
• Further research with larger, more controlled populations is warranted to validate and expand on these findings.