Head, withers and pelvic movement asymmetry and their relative timing in trot in racing Thoroughbreds in training

Abstract

SummaryBackgroundHorses show compensatory head movement in hindlimb lameness and compensatory pelvis movement in forelimb lameness but little is known about the relationship of withers movement symmetry with head and pelvic asymmetry in horses with naturally occurring gait asymmetries.ObjectivesTo document head, withers and pelvic movement asymmetry and timing differences in horses with naturally occurring gait asymmetries.Study designRetrospective analysis of gait data.MethodsHead, withers and pelvic movement asymmetry and timing of displacement minima and maxima were quantified from inertial sensors in 163 Thoroughbreds during trot‐ups on hard ground. Horses were divided into 4 subgroups using the direction of head and withers movement asymmetry. Scatter plots of head vs. pelvic movement asymmetry illustrated how the head–withers relationship distinguishes between contralateral and ipsilateral head–pelvic movement asymmetry. Independent t test or Mann–Whitney U test (P<0.05) compared pelvic movement asymmetry and timing differences between groups.ResultsThe relationship between head and withers asymmetry (i.e. same sided or opposite sided asymmetry) predicts the relationship between head and pelvic asymmetry in 69–77% of horses. Pelvic movement symmetry was significantly different between horses with same sign vs. opposite sign of head–withers asymmetry (P<0.0001). Timing of the maximum head height reached after contralateral (‘sound’) stance was delayed compared to withers (P = 0.02) and pelvis (P = 0.04) in horses with contralateral head–withers asymmetry.Main limitationsThe clinical lameness status of the horses was not investigated.ConclusionIn the Thoroughbreds with natural gait asymmetries investigated here, the direction of head vs. withers movement asymmetry identifies the majority of horses with ipsilateral and contralateral head and pelvic movement asymmetries. Withers movement should be further investigated for differentiating between forelimb and hindlimb lame horses. Horses with opposite sided head and withers asymmetry significantly delay the upward movement of the head after ‘sound’ forelimb stance.

Comparison of visual lameness scores to gait asymmetry in racing Thoroughbreds during trot in‐hand

“…) and that racing Thoroughbreds show these patterns (Pfau et al . ), we further (qualitatively) investigated the head‐withers movement asymmetry relationship.…”

“…; Pfau et al . ). For qualitative comparison between visual assessment and quantitative asymmetry measurement, the side of lameness was defined from HDmin for forelimb lameness and PDmin for hindlimb lameness (based on previously identified associations with peak force asymmetry (Keegan et al .…”

“…For categorising existence and side of lameness, previously reported clinical thresholds values of >|6 mm| for head movement asymmetry and >|3 mm| for pelvic movement asymmetry (McCracken et al 2012) were adapted to >|7 mm| for HDmin and >|4 mm| for PDmin based on correction equations presented in (Pfau et al 2016a). Horses with HDmin and WDmin values showing same signs were categorised as forelimb lame, horses with HDmin and WDmin of opposite sign were categorised as hindlimb lame (Persson-Sjodin et al 2016;Pfau et al 2017). For qualitative comparison between visual assessment and quantitative asymmetry measurement, the side of lameness was defined from HDmin for forelimb lameness and PDmin for hindlimb lameness (based on previously identified associations with peak force asymmetry Bell et al 2016)).…”

Research trends in equine movement analysis, future opportunities and potential barriers in the digital age: A scoping review from 1978 to 2018

“…These extremes cause translational difficulties, in which stakeholders may be uncomfortable with the ‘black box’ element of the data analysis and interpretation – particularly automated interpretation of ‘normal’ or ‘abnormal’. Thresholding and categorising horses against population norms is no longer considered a worthy indicator of normality/abnormality . A recent review of induced lameness research suggested that we must anticipate that objective gait quantification techniques will become the monitoring standard in equine gait analysis .…”

Practical uses of quantitative gait analysis in horses

“…Its use in aiding lameness diagnosis and monitoring is mainly based on measuring gait asymmetries, determining whether those asymmetries are over pre-set thresholds and deciding on their clinical relevance. Much work has already been done to investigate symmetry and asymmetry values of the motion of various body parts (including vertical displacement of head, withers and pelvis; joint angle parameters of the limbs and vertebral column), stride parameters and limb loading; as well as the symmetry values seen under different conditions such as different disciplines, training, type of terrain, with or without a rider and during lungeing or when moving over a straight line [1][2][3][4][5][6][7]. Further refinement of knowledge on gait parameters is still warranted, and research in the area will not cease as technologies evolve.Although perfectly suited for the purpose, quantitative gait analysis has been used in very few studies of neurological conditions.…”