An inertial sensor-based system can objectively assess diagnostic anaesthesia of the equine foot.

The research presents evidence pointing to the effective use of an inertial sensor-based system to differentiate between positive and negative responses in horses subjected to diagnostic anaesthesia of the foot.

Objective of the Research

The primary aim of this research was to establish whether an inertial sensor-based system can:

• Distinguish between a positive and negative response from horses subjected to diagnostic anaesthesia of the foot.
• Objectively measure the effect of the positive reaction during trotting.

Methodology

The approach taken to carry out the testing involved a retrospective clinical study, utilizing:

• Data obtained from lameness investigations carried out between August 2011 and December 2012.
• In these investigations, either a palmar digital or abaxial sesamoid nerve block had been implemented.
• A response to diagnostic anaesthesia was classified as either positive or negative by blind evaluators.
• The alterations in maximum and minimum head difference (ΔHDMax and ΔHDMin) and change in head movement asymmetry/change in pelvic movement asymmetry (ΔHMA/PMA, measure of asymmetry) allocated to each limb were measured.
• Finally, to identify cut-off values that would separate positive and negative responses to the block, Receiver Operating Characteristic (ROC) curves were generated.

Results

The results of the study confirmed that:

• The Median ΔHDMax and ΔHDMin recorded were significantly greater after a positive response to diagnostic anaesthesia.
• Change in head movement asymmetry allocated to the blocked limb and contralateral forelimb and ΔPMA allocated to the contralateral hindlimb was significantly greater in the positive response group.
• Change in head movement asymmetry was found useful in identifying positive responses to anaesthesia, proving it to be very reliable.

Conclusions

In conclusion, the research determined that:

• An inertial sensor-based system effectively identifies a positive response to diagnostic anaesthesia of the foot in horses.
• In horses demonstrating a positive response, symmetry of movement allocated to the blocked limb, contralateral forelimb and contralateral hindlimb significantly improved, and head movement significantly decreased.
• The research provided cut-off values for a positive response which were identified to have high sensitivity and specificity.
• The study also found that forelimb lameness significantly affects contralateral hindlimb movement – a finding that has implications for the investigation of multi-limb lameness.