The Feasibility of Equine Field-Based Postural Sway Analysis Using a Single Inertial Sensor

Abstract

(1) Background: Postural sway is frequently used to quantify human postural control, balance, injury, and neurological deficits. However, there is considerably less research investigating the value of the metric in horses. Much of the existing equine postural sway research uses force or pressure plates to examine the centre of pressure, inferring change at the centre of mass (COM). This study looks at the inverse, using an inertial measurement unit (IMU) on the withers to investigate change at the COM, exploring the potential of postural sway evaluation in the applied domain. (2) Methods: The lipopolysaccharide model was used to induce transient bilateral lameness in seven equines. Horses were monitored intermittently by a withers fixed IMU over seven days. (3) Results: There was a significant effect of time on total protein, carpal circumference, and white blood cell count in the horses, indicating the presence of, and recovery from, inflammation. There was a greater amplitude of displacement in the craniocaudal (CC) versus the mediolateral (ML) direction. A significant difference was observed in the amplitude of displacement in the ML direction between 4–12 h and 168 h.; (4) Conclusions: The significant reduction in ML displacement during the acute inflammation period alongside greater overall CC displacement may be a compensatory behaviour for bilateral lameness.

Validation of inertial measurement units to detect and predict horse behaviour while stabled

“…Further, behaviours occurring concurrently to those recorded by the IMU, but that were not accounted for in this study (e.g., eating while standing or weight‐shifting), may also require separate labelling. Other solutions may include employing more sensitive means of validating weight shifts that do not rely on visual classification (e.g., force plates), 63 accounting for the behavioural states over a longer time period preceding and following standing, or investigating alternatives such as using a single wither sensor to detect mediolateral postural sway as an indicator of subtle weight shifts in limb pairs as has been used to identify horses with constrained postural control 42 . As well as investigating associations between occurrence of specific behaviours with orthopaedic pain in future studies, transition and variability of behaviour may also be important predictors of pain, warranting further investigation.…”

“…Algorithms have been developed and validated to classify dog behaviour with excellent agreement (>0.90), 37 detect lameness in sheep with an 82% accuracy, 38 monitor lying behaviour in cattle 39 and predict foaling in broodmares 40 . More recently, IMUs have been used to predict step count in horses under stall confinement with excellent agreement (>0.99), 41 and assess changes in postural sway for horses with induced lameness 42 …”

“…40 More recently, IMUs have been used to predict step count in horses under stall confinement with excellent agreement (>0.99), 41 and assess changes in postural sway for horses with induced lameness. 42 Effective remote monitoring of horses could be used in racing stables to detect subtle changes in behaviour. The objective of this study was to determine whether IMUs are sensitive enough to detect horse behaviours when compared with intensive methods, such as constant observation, in what would be considered a healthy population, as orthopaedic pain can be sub-clinical.…”

Accelerometry-Based Step Count Validation for Horse Movement Analysis During Stall Confinement

“…As such, the reason for monitoring a horse is usually insufficient movement, which may be indicative of inadequate pain control or the development of immobility-associated complications. Measuring movement in injured horses could prove to be challenging with added alterations in movement, such as reduced and altered loading patterns due to pain, changes in gait patterns due to asymmetries (2,5,(21)(22)(23), as well as decreased stability and increased postural sway (24), all of which can be affected to varying degrees depending on the type, location and severity of the injury (25). Consequently, free movement analysis would likely be the most important measure in these circumstances.…”

State-of-the-Art Sensors Research in Ireland

“…The feasibility of equine, field-based, postural sway analysis using a single inertial sensor was investigated by Egan et al [19]. This is the first study to investigate how often and for how long equines settle into a state of quiet standing, which would enable the analysis of postural sway captured in the applied setting.…”