Gait characterisation and classification in horses

Abstract

SUMMARY Although a large number of foot-fall sequences are possible in quadrupeds,few sequences are routinely used. The aim of this paper is to characterise, by foot-fall pattern, the gaits used by horses and develop a novel technique to classify symmetric and asymmetric gaits using one common criterion. To achieve this speed and relative foot-fall, timings of all four limbs of eight Icelandic horses were measured using accelerometers. Linear discriminant analysis (LDA) was performed to find criteria that are optimal for discriminating between the different gaits. This also allowed us to evaluate whether gaits should be considered a continuum or as discrete entities. Foot-fall timings (stance times, swing times, duty factors and stride frequencies) for walk, tolt, trot, pace, left canter, right canter, left gallop and right gallop during over-ground locomotion at a range of speeds are presented. In the gaits of walk, tolt, trot and pace, foot-fall timings were equal between left and right hindlimbs and forelimbs so these gaits can be considered as symmetrical. Differences in stance times and duty factors were observed between gaits but are unlikely to be of biological significance due to their similar magnitude and inconsistent relative trends. This implies that metabolics or peak limb forces derived from contact times are unlikely to be the principal driving factors in gait transition between walk, trot, pace,canters and gallops, although these factors may influence the use of tolt at the lower and higher speeds. Gaits did cluster in the LDA space and the running gaits (tolt, trot, pace, left and right canters and gallops) could be considered a kinematic continuum but the relative relationship with walk may be more complex. Thus, LDA analysis has enabled common criteria to be discovered to accurately classify equine gaits on the basis of foot-fall timings on a stride-by-stride basis.

Walk–run classification of symmetrical gaits in the horse: a multidimensional approach

“…In this study, we have gathered experimental evidence on whether tölt, a symmetrical four-beat gait most commonly found in Icelandic horses (Zips et al 2001;Nicodemus & Clayton 2003;Biknevicius et al 2004Biknevicius et al , 2006Robilliard et al 2007), is more similar to walking or to the other symmetrical running gaits (i.e. trot and pace).…”

“…As a result of the range of speeds seen in tölt (Zips et al 2001;Biknevicius et al 2006;Robilliard et al 2007), dimensionless speeds predominantly fall into the running category; however, some values for dimensionless speed fall into the walking category (Biknevicius et al 2004(Biknevicius et al , 2006Robilliard et al 2007). Biknevicius et al (2006) also reported comparatively low values for PR (mean 7.9%) consistent with spring-mass mechanics.…”

“…The horses used were naturally five gaited and were ridden in the four symmetrical gaits (walk, trot, pace and tölt) and in the asymmetrical gait of canter/gallop (see Robilliard et al (2007) for more detail). For the study presented here, 6138 strides corresponding to the symmetrical gaits were used.…”

“…The number of strides per gait and horse ranged from 19 to 456 (see table 1 for details). In addition to speed and limb-timing information (Robilliard et al 2007), the horses were equipped with a small inertial sensor (modified MT9, Xsens, Enschede, The Netherlands) attached underneath the most cranial edge of the saddle over the withers using a custom-made harness (Pfau et al 2005(Pfau et al , 2006. This sensor gives accurate six degrees of freedom movement information for the withers of the horse (Pfau et al 2005) and allows estimation of the centre of mass movement (Pfau et al 2006;Parsons et al 2008) and thus calculation of potential and kinetic energy fluctuations (Pfau et al 2006).…”

“…Initially, each of the four individual features was used to determine a threshold value to discriminate between walking and running. This was achieved using all the walk strides (see Robilliard et al (2007) for details about gait classification) for the walking category and all the trot and pace strides for the running category. The thresholds were selected based on the sensitivity and specificity achieved for the individual features.…”