Compensatory load redistribution of horses with induced weightbearing hindlimb lameness trotting on a treadmill

Investigating Associations between Horse Hoof Conformation and Presence of Lameness

Hoof trimming and shoeing determine the horse's hoof shape and balance. Hoof conformation plays a crucial role in limb biomechanics and can consequently prevent or predispose to injury. This study investigated the relationship between the morphometric characteristics of the horse's hoof, specifically, the dorsal hoof wall angle (DHWA), the coronet band circumference (CBC), and lameness in 73 horses categorised as undertaking either show jumping, dressage, or riding school activities. Results from logistic regression indicated that horses with either a combination of acute DHWA with large CBC, or more upright feet with larger DHWA and smaller CBC have higher probabilities of lameness. Show jumping and dressage horses showed a higher prevalence of lameness. Hoof morphometry should be monitored, and podiatric interventions should be regularly scheduled for the maintenance of correct hoof conformation to prevent injury. This study suggests that an aligned hoof-pastern axis managed by a DHWA of around 50 degrees may prevent lameness, with special emphasis on horses in dressage and show jumping activities. On the other hand, we can also speculate that the disturbed axis alignment of DHWA may be a cause of lameness.

Kinematic changes in dairy cows with induced hindlimb lameness: transferring methodology from the field of equine biomechanics

Lameness is a common issue on dairy farms, with serious implications for economy and animal welfare. Affected animals may be overlooked until their condition becomes severe. Thus, improved lameness detection methods are needed. In this study, we describe kinematic changes in dairy cows with induced, mild to moderate hindlimb lameness in detail using a "whole-body approach". Thereby, we aimed to identify explicable features to discriminate between lame and non-lame animals for use in future automated surveillance systems. For this purpose, we induced a mild to moderate and fully reversible hindlimb lameness in 16 dairy cows. We obtained 41 straight-line walk measurements (containing > 3 000 stride cycles) using 11 inertial measurement units attached to predefined locations on the cows' upper body and limbs. One baseline and ≥ 1 induction measurement(s) were obtained from each cow. Thirty-one spatial and temporal parameters related to limb movement and inter-limb coordination, upper body vertical displacement symmetry and range of motion (ROMz), as well as pelvic pitch and roll, were calculated on a stride-by-stride basis. For upper body locations, vertical within-stride movement asymmetry was investigated both by calculating within-stride differences between local extrema, and by a signal decomposition approach. For each parameter, the baseline condition was compared with induction condition in linear mixed-effect models, while accounting for stride duration. Significant difference between baseline and induction condition was seen for 23 out of 31 kinematic parameters. Lameness induction was associated with decreased maximum protraction (-5.8%) and retraction (-3.7%) angles of the distal portion of the induced/non-induced limb respectively. Diagonal and lateral dissociation of foot placement (ratio of stride duration) involving the non-induced limb decreased by 8.8 and 4.4%, while diagonal dissociation involving the induced limb increased by 7.7%. Increased within-stride vertical displacement asymmetry of the poll, neck, withers, thoracolumbar junction (back) and tubera sacrale (TS) were seen. This was most notable for the back and poll, where a 40 and 24% increase of the first harmonic amplitude (asymmetric component) and 27 and 14% decrease of the second harmonic amplitude (symmetric component) of vertical displacement were seen. ROMz increased in all these landmarks except for TS. Changes in pelvic roll main components, but not in the range of motion of either pitch or roll angle per stride, were seen. Thus, we identified several kinematic features which may be used in future surveillance systems. Further studies are needed to determine their usefulness in realistic conditions, and to implement methods on farms.

Vertical pelvic movement asymmetry and lameness location in ipsilateral combined forelimb and hindlimb lameness cases

BACKGROUND

Compensatory vertical head and pelvis movement asymmetry may occur in trotting horses with a primary cause of lameness in one end of the body due to the weight shifting between limbs, leading to apparent combined forelimb and hindlimb lameness (CFHL). Little is known about CFHL patterns observed with body-mounted inertial sensors (BMIS) and regardless of their underlying mechanisms, compensatory and secondary lameness may complicate the definitive identification of the primary causes of lameness.

OBJECTIVE

Determine associations between vertical pelvic movement asymmetry and location of primary lameness in ipsilateral CFHL cases where hindlimb lameness is solely impact or push-off type.

STUDY DESIGN

Retrospective cohort.

METHODS

From a body-mounted inertial sensor (BMIS) evaluated equine lameness database, we identified cases with a consistent, low-variability ipsilateral impact (IpI) or ipsilateral pushoff (IpP) hindlimb lameness in a straight-line trot and that had definitive diagnoses. Cases were categorised by lameness location to the limb(s), diagnosis, and ratio of the amplitude of forelimb to hindlimb lameness (Forea/Hinda). Differences in the numbers of IpI and IpP cases in these categories were analysed with chi-square tests, effect sizes, and odds ratios.

RESULTS

Among the 2375 total lameness cases screened, 49 IpI and 36 IpP cases met the criteria for consistency, low variability, and definitive diagnosis. IpI cases were more likely than IpP cases to have forelimb-only lameness causes when Forea/Hinda >1 (OR = 43, 95% CI = 2.3-798). IpP cases were more likely than IpI cases to have hindlimb-only causes at both Forea/Hinda >1.0 (OR = 20, 95% CI = 2.2-200) and <1.0 (OR = 14, 95% CI = 2.9-66.7). Compared with IpI, IpP cases were more frequently diagnosed with tendon, suspensory ligament, or high-motion joint disorders in hindlimbs (OR = 3.6, 95% CI = 1.1-12.3) and less with unknown causes (OR = 13.2, 95% CI = 3.2-75.2). In IpI cases, positive forelimb regional anaesthesia often reduced hindlimb lameness, whereas in IpP cases, positive hindlimb regional anaesthesia typically lessened forelimb lameness.

MAIN LIMITATIONS

Most cases were Quarter Horses. The likelihood of location and cause of lameness may be different for other breeds.

CONCLUSIONS

The type of pelvic movement asymmetry observed in IpI and IpP cases is linked to the location and underlying cause of the primary lameness.

Adaptation strategies of the Icelandic horse with induced forelimb lameness at walk, trot and tölt

BACKGROUND AND OBJECTIVE

Lameness assessment in the gaited Icelandic horse is complex. We aimed to describe their kinematic and temporal adaptation strategies in response to forelimb lameness at walk, trot and tölt.

STUDY DESIGN

In vivo experiment.

METHODS

Ten clinically non-lame Icelandic horses were measured before and after reversible forelimb lameness induction. Upper body and limb kinematics were measured using 11 inertial measurement units mounted on the poll, withers, pelvis (tubera sacrale) and all four limbs and hoofs (Equimoves®, 500 Hz). Horses were measured on a straight line at walk and trot in-hand and at walk, trot and tölt while ridden. Linear mixed models were used to compare baseline and lame conditions (random factor = 'horse'), and results are presented as the difference in estimated marginal means or percentage of change.

RESULTS

Lameness induction significantly (p < 0.05) increased head vertical movement asymmetry at walk (HDmin/HDmaxHAND: 18.8/5.7 mm, HDmin/HDmaxRIDDEN: 9.8/0.3 mm) and trot (HDmin/HDmaxHAND: 18.1/7.8 mm, HDmin/HDmaxRIDDEN: 24.0/9.3 mm). At the tölt, however, HDmin did not change significantly (1.1 mm), but HDmax increased by 11.2 mm (p < 0.05). Furthermore, pelvis vertical movement asymmetry (PDmax) increased by 4.9 mm, sound side dissociation decreased (-8.3%), and sound diagonal dissociation increased (6.5%). Other temporal stride variables were also affected, such as increased stance duration of both forelimbs at walk, tölt and in-hand trot.

MAIN LIMITATIONS

Only one degree of lameness (mild) was induced with an acute lameness model.

CONCLUSIONS

Classical forelimb lameness metrics, such as vertical head and withers movement asymmetry, were less valuable at tölt compared to walk and trot, except for HDmax. Therefore, it is advised to primarily use the walk and trot to detect and quantify forelimb lameness in the Icelandic horse.

Classification performance of sEMG and kinematic parameters for distinguishing between non-lame and induced lameness conditions in horses

Despite its proven research applications, it remains unknown whether surface electromyography (sEMG) can be used clinically to discriminate non-lame from lame conditions in horses. This study compared the classification performance of sEMG absolute value (sEMGabs) and asymmetry (sEMGasym) parameters, alongside validated kinematic upper-body asymmetry parameters, for distinguishing non-lame from induced fore- (iFL) and hindlimb (iHL) lameness. Bilateral sEMG and 3D-kinematic data were collected from clinically non-lame horses (n = 8) during in-hand trot. iFL and iHL (2-3/5 AAEP) were induced on separate days using a modified horseshoe, with baseline data initially collected each day. sEMG signals were DC-offset removed, high-pass filtered (40 Hz), and full-wave rectified. Normalized, average rectified value (ARV) was calculated for each muscle and stride (sEMGabs), with the difference between right and left-side ARV representing sEMGasym. Asymmetry parameters (MinDiff, MaxDiff, Hip Hike) were calculated from poll, withers, and pelvis vertical displacement. Receiver-operating-characteristic (ROC) and area under the curve (AUC) analysis determined the accuracy of each parameter for distinguishing baseline from iFL or iHL. Both sEMG parameters performed better for detecting iHL (0.97 ≥ AUC ≥ 0.48) compared to iFL (0.77 ≥ AUC ≥ 0.49). sEMGabs performed better (0.97 ≥ AUC ≥ 0.49) than sEMGasym (0.76 ≥ AUC ≥ 0.48) for detecting both iFL and iHL. Like previous studies, MinDiff Poll and Pelvis asymmetry parameters (MinDiff, MaxDiff, Hip Hike) demonstrated excellent discrimination for iFL and iHL, respectively (AUC > 0.95). Findings support future development of multivariate lameness-detection approaches that combine kinematics and sEMG. This may provide a more comprehensive approach to diagnosis, treatment, and monitoring of equine lameness, by measuring the underlying functional cause(s) at a neuromuscular level.

Application of the Ridden Horse Pain Ethogram to 150 Horses with Musculoskeletal Pain before and after Diagnostic Anaesthesia

The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate the recognition of musculoskeletal pain. The aim of this study was to document changes in RHpE scores before and after diagnostic anaesthesia was performed to alleviate pain ± when the saddle was changed. One hundred and fifty horses underwent ridden exercise as part of an investigation of poor performance. The RHpE was applied before and after the interventions. Fifty-two (34.7%) horses exhibited a bilaterally symmetrical short step length and/or restricted hindlimb impulsion and engagement. Fifty-three (35.3%) horses had episodic lameness; only forty-five (30.0%) horses were continuously lame. The median maximum lameness grade when ridden was 2/8 (interquartile range [IQR]: 0-3; range: 0-4). Fifty-six (37.3%) horses had an ill-fitting saddle, which was considered likely to influence performance. The median RHpE scores after the interventions (2/24 [IQR: 1-3, range: 0-12]) were significantly lower than before the interventions (9/24 [IQR: 8-11, range: 2-15]) (Wilcoxon signed-rank z = 10.6, p < 0.001). There was no correlation between the RHpE score and maximum lameness grade before diagnostic anaesthesia (Spearman's rho = 0.09, p = 0.262). It was concluded that the absence of overt lameness does not preclude primary musculoskeletal pain. Gait quality and performance can be improved by diagnostic anaesthesia, with substantial reductions in RHpE scores.

Prediction of continuous and discrete kinetic parameters in horses from inertial measurement units data using recurrent artificial neural networks

Vertical ground reaction force (GRFz) measurements are the best tool for assessing horses' weight-bearing lameness. However, collection of these data is often impractical for clinical use. This study evaluates GRFz predicted using data from body-mounted IMUs and long short-term memory recurrent neural networks (LSTM-RNN). Twenty-four clinically sound horses, equipped with IMUs on the upper-body (UB) and each limb, walked and trotted on a GRFz measuring treadmill (TiF). Both systems were time-synchronised. Data from randomly selected 16, 4, and 4 horses formed training, validation, and test datasets, respectively. LSTM-RNN with different input sets (All, Limbs, UB, Sacrum, or Withers) were trained to predict GRFz curves or peak-GRFz. Our models could predict GRFz shapes at both gaits with RMSE below 0.40 N.kg^-1. The best peak-GRFz values were obtained when extracted from the predicted curves by the all dataset. For both GRFz curves and peak-GRFz values, predictions made with the All or UB datasets were systematically better than with the Limbs dataset, showing the importance of including upper-body kinematic information for kinetic parameters predictions. More data should be gathered to confirm the usability of LSTM-RNN for GRFz predictions, as they highly depend on factors like speed, gait, and the presence of weight-bearing lameness.

Adaptations in equine appendicular muscle activity and movement occur during induced fore- and hindlimb lameness: An electromyographic and kinematic evaluation

The relationship between lameness-related adaptations in equine appendicular motion and muscle activation is poorly understood and has not been studied objectively. The aim of this study was to compare muscle activity of selected fore- and hindlimb muscles, and movement of the joints they act on, between baseline and induced forelimb (iFL) and hindlimb (iHL) lameness. Three-dimensional kinematic data and surface electromyography (sEMG) data from the fore- (triceps brachii, latissimus dorsi) and hindlimbs (superficial gluteal, biceps femoris, semitendinosus) were bilaterally and synchronously collected from clinically non-lame horses (n = 8) trotting over-ground (baseline). Data collections were repeated during iFL and iHL conditions (2-3/5 AAEP), induced on separate days using a modified horseshoe. Motion asymmetry parameters and continuous joint and pro-retraction angles for each limb were calculated from kinematic data. Normalized average rectified value (ARV) and muscle activation onset, offset and activity duration were calculated from sEMG signals. Mixed model analysis and statistical parametric mapping, respectively, compared discrete and continuous variables between conditions (α= 0.05). Asymmetry parameters reflected the degree of iFL and iHL. Increased ARV occurred across muscles following iFL and iHL, except non-lame side forelimb muscles that significantly decreased following iFL. Significant, limb-specific changes in sEMG ARV, and activation timings reflected changes in joint angles and phasic shifts of the limb movement cycle following iFL and iHL. Muscular adaptations during iFL and iHL are detectable using sEMG and primarily involve increased bilateral activity and phasic activation shifts that reflect known compensatory movement patterns for reducing weightbearing on the lame limb. With further research and development, sEMG may provide a valuable diagnostic aid for quantifying the underlying neuromuscular adaptations to equine lameness, which are undetectable through human observation alone.

Kinetic Analysis in Horses With Deep Digital Flexor Tendinopathy Within the Digit Diagnosed by Magnetic Resonance Imaging

Objectives

To determine the stance duration and ground reaction forces (GRF) of horses with deep digital flexor (DDF) tendinopathy at the level of the foot and compare the stance duration and GRF to those of clinically sound horses.

Design

Prospective clinical study.

Animals

Sixteen horses (seven horses with bilateral forelimb lameness, four horses with unilateral forelimb lameness, and five horses with no lameness).

Procedures

Analyses of kinetic variables were performed on both forelimbs from sound horses and horses diagnosed with chronic DDF tendinopathy. Stance duration and longitudinal and vertical components of the GRF were determined for the limbs of clinically sound horses and limbs of horses with DDF tendinopathy. Separate Spearman correlation analyses were used to assess potential association within groups (combined left and right forelimbs of clinically sound horses, lamest limbs of horses with DDF tendinopathy, and contralateral limbs of horses with DDF tendinopathy) and with the set of kinetic variables. Analysis of variance on mean ranks of tied values was used to determine differences in kinetic variables between groups (PROC GLIMMIX) using the kinetic values of the clinically sound horses as the reference group.

Results

There were a total of 11 lame horses. Seven horses had bilateral forelimb lameness and four had unilateral lameness. Of the 11 horses, there were 15 DDF tendinopathies. There were eight dorsal border DDF tendinopathies, five core DDF tendinopathies, and two sagittal/parasagittal splits DDF tendinopathies. The most lame limbs of horses with DDF tendinopathy had significantly smaller values for peak vertical force and time of peak braking force than did forelimbs of clinically sound horses. Also, the most lame limbs of horses with DDF tendinopathy had significantly larger values for the time of peak vertical force than did forelimbs of clinically sound horses.

Conclusions and Clinical Relevance

Horses with chronic DDF tendinopathies develop certain alterations of GRF parameters. This information can be used in future studies to determine if particular kinetic variable changes in horses with DDF tendinopathies differ from those of horses with other pathologies within the foot and therefore could be diagnostic.

Linear Discriminant Analysis for Investigating Differences in Upper Body Movement Symmetry in Horses before/after Diagnostic Analgesia in Relation to Expert Judgement

Simple Summary

Identifying the anatomical structures involved in causing pain and an associated lameness in a horse typically requires assessment in straight lines and circles and using regional administration of local anesthetic drugs (diagnostic analgesia). Visual assessment of changes in movement are affected by bias, i.e., expected changes influence decisions. Quantitative measurements with inertial sensors aim at removing this bias. The current study is aimed at investigating how a specific data-driven method, linear discriminant analysis (LDA), may be useful for aiding veterinary decision making about perceived changes in lameness. Changes in movement data after diagnostic analgesia and expert judgements from 53 lame horses were used to study (a) the accuracy of LDA-based decision making, (b) differences between straight-line and circular movement and (c) which commonly used movement features are most useful in this context. Accuracy was comparatively low and varied considerably between 36% and 57%, indicating considerable overlap between movement symmetry data of the diagnostic analgesia categories. The best data-driven separation between categories was observed when the limb in which perineural anaesthesia had been performed was on the inside of the circle (on hard ground for forelimb and on soft ground for hindlimb diagnostic analgesia). Movement features of all three landmarks (head, withers, pelvis) were important for data-driven classification, emphasizing the complexity of the movement pattern changes after diagnostic analgesia observed in lame horses.

Abstract

Diagnostic analgesia and lunging are parts of the equine lameness examination, aiding veterinarians in localizing the anatomical region(s) causing pain-related movement deficits. Expectation bias of visual assessment and complex movement asymmetry changes in lame horses on the lunge highlight the need to investigate data-driven approaches for optimally integrating quantitative gait data into veterinary decision-making to remove bias. A retrospective analysis was conducted with inertial sensor movement symmetry data before/after diagnostic analgesia relative to subjective judgement of efficacy of diagnostic analgesia in 53 horses. Horses were trotted on the straight and on the lunge. Linear discriminant analysis (LDA) applied to ten movement asymmetry features quantified the accuracy of classifying negative, partial and complete responses to diagnostic analgesia and investigated the influence of movement direction and surface type on the quality of the data-driven separation between diagnostic analgesia categories. The contribution of movement asymmetry features to decision-making was also studied. Leave-one-out classification accuracy varied considerably (38.3–57.4% for forelimb and 36.1–56.1% for hindlimb diagnostic analgesia). The highest inter-category distances (best separation) were found with the blocked limb on the inside of the circle, on hard ground for forelimb diagnostic analgesia and on soft ground for hindlimb diagnostic analgesia. These exercises deserve special attention when consulting quantitative gait data in lame horses. Head and pelvic upward movement and withers minimum differences were the features with the highest weighting within the first canonical LDA function across exercises and forelimb and hindlimb diagnostic analgesia. This highlights that movement changes after diagnostic analgesia affect the whole upper body. Classification accuracies based on quantitative movement asymmetry changes indicate considerable overlap between subjective diagnostic analgesia categories.

Smartphone-Based Pelvic Movement Asymmetry Measures for Clinical Decision Making in Equine Lameness Assessment

Simple Summary

As visual evaluation of hindlimb lameness in the horse is challenging, objective measurements could aid clinical decision making. Our study investigated the association of pelvic movement asymmetry, recorded via a smartphone, with lameness scores of one experienced veterinarian. In general, cut-off points between lameness grades increased with increasing severity of lameness. Pelvic upward movement amplitude difference was the asymmetry parameter with the highest discriminative power based on subjective lameness scoring of a specialist veterinarian. This parameter classified a higher proportion of lame and non-lame horses correctly compared to the parameters assessing differences between pelvic vertical movement minima and maxima. Although the use of a smartphone measuring only the symmetry of pelvis cannot replace a full lameness examination, it presents a useful adjunct to subjective evaluation alone. Quantification of pelvic asymmetry with a smartphone may also be a useful tool in the context of tracking progress after a treatment or during the rehabilitation process.

Abstract

Visual evaluation of hindlimb lameness in the horse is challenging. Objective measurements, simultaneous to visual assessment, are used increasingly to aid clinical decision making. The aim of this study was to investigate the association of pelvic movement asymmetry with lameness scores (UK scale 0–10) of one experienced veterinarian. Absolute values of pelvic asymmetry measures, quantifying differences between vertical minima (AbPDMin), maxima (AbPDMax) and upward movement amplitudes (AbPDUp), were recorded during straight-line trot with a smartphone attached to the sacrum (n = 301 horses). Overall, there was a significant difference between lameness grades for all three asymmetry measures (p < 0.001). Five pair-wise differences (out of 10) were significant for AbPDMin (p≤ 0.02) and seven for AbPDMax (p≤ 0.03) and AbPDUp (p≤ 0.02). Receiver operating curves assessed sensitivity and specificity of asymmetry measures against lameness scores. AbPDUp had the highest discriminative power (area under curve (AUC) = 0.801–0.852) followed by AbPDMax (AUC = 0.728–0.813) and AbPDMin (AUC = 0.688–0.785). Cut-off points between non-lame (grade 0) and lame horses (grades 1–4) with a minimum sensitivity of 75% were identified as AbPDUp ≥ 7.5 mm (67.6% specificity), AbPDMax ≥ 4.5 mm (51.9% specificity) and AbPDMin ≥ 2.5 mm (33.3% specificity). In conclusion, pelvic upward movement amplitude difference (AbPDUp) was the asymmetry parameter with the highest discriminative power in this study.

Continuous versus discrete data analysis for gait evaluation of horses with induced bilateral hindlimb lameness

Background

Gait kinematics measured during equine gait analysis are typically evaluated by analysing (asymmetry‐based) discrete variables (eg, peak values) obtained from continuous kinematic signals (eg, timeseries of datapoints). However, when used for the assessment of complex cases of lameness, such as bilateral lameness, discrete variable analysis might overlook relevant functional adaptations.

Objectives

The overall aim of this paper is to compare continuous and discrete data analysis techniques to evaluate kinematic gait adaptations to lameness.

Study design

Method comparison.

Methods

Sixteen healthy Shetland ponies, enrolled in a research programme in which osteochondral defects were created on the medial trochlear ridges of both femurs, were used in this study. Kinematic data were collected at trot on a treadmill before and at 3 and 6 months after surgical intervention. Statistical parametric mapping and linear mixed models were used to compare kinematic variables between and within timepoints.

Results

Both continuous and discrete data analyses identified changes in pelvis and forelimb kinematics. Discrete data analyses showed significant changes in hindlimb and back kinematics, where such differences were not found to be significant by continuous data analysis. In contrast, continuous data analysis provided additional information on the timing and duration of the differences found.

Main limitations

A limited number of ponies were included.

Conclusions

The use of continuous data provides additional information regarding gait adaptations to bilateral lameness that is complementary to the analysis of discrete variables. The main advantage lies in the additional information regarding time dependence and duration of adaptations, which offers the opportunity to identify functional adaptations during all phases of the stride cycle, not just the events related to peak values.

The Protraction and Retraction Angles of Horse Limbs: An Estimation during Trotting Using Inertial Sensors

The protraction and retraction angles of horse limbs are important in the analysis of horse locomotion. This study explored two methods from an IMU positioned on the canon bone of eight horses to estimate these angles. Each method was based on a hypothesis in order to define the moment corresponding with the verticality of the canon bone: (i) the canon bone is in a vertical position at 50% of the stance phase or (ii) the verticality of the canon bone corresponds with the moment when the horse’s withers reach their lowest point. The measurements were carried out on a treadmill at a trot and compared with a standard gold method based on motion capture. For the measurement of the maximum protraction and retraction angles, method (i) had average biases (0.7° and 1.7°) less than method (ii) (−1.3° and 3.7°). For the measurement of the protraction and retraction angles during the stance phase, method (i) had average biases (4.1° and −3.3°) higher to method (ii) (2.1° and −1.3°). This study investigated the pros and cons of a generic method (i) vs. a specific method (ii) to determine the protraction and retraction angles of horse limbs by a single IMU.

Cutaneous tactile sensitivity before and after tail loss and regeneration in the leopard gecko (Eublepharis macularius)

Amongst tetrapods, mechanoreceptors on the feet establish a sense of body placement and help to facilitate posture and biomechanics. Mechanoreceptors are necessary for stabilizing the body while navigating through changing terrains or responding to a sudden change in body mass and orientation. Lizards such as the leopard gecko (Eublepharis macularius) employ autotomy – a voluntary detachment of a portion of the tail – to escape predation. Tail autotomy represents a natural form of significant (and localized) mass loss. Semmes–Weinstein monofilaments were used to investigate the effect of tail autotomy (and subsequent tail regeneration) on tactile sensitivity of each appendage of the leopard gecko. Prior to autotomy, we identified site-specific differences in tactile sensitivity across the ventral surfaces of the hindlimbs, forelimbs and tail. Repeated monofilament testing of both control (tail-intact) and tail-loss geckos had a significant sensitization effect (i.e. decrease in tactile threshold, maintained over time) in all regions of interest except the palmar surfaces of the forelimbs in post-autotomy geckos, compared with baseline testing. Although the regenerated tail is not an exact replica of the original, tactile sensitivity is shown to be effectively restored at this site. Re-establishment of tactile sensitivity on the ventral surface of the regenerate tail points towards a (continued) role in predator detection.

Riding Soundness-Comparison of Subjective With Objective Lameness Assessments of Owner-Sound Horses at Trot on a Treadmill

Lameness is a symptom indicative of pain or injury of the locomotor apparatus. Lame horses generally should not be ridden. However, owners' ability to assess lameness has been questioned. This study's aim was to use subjective lameness assessments and objective gait analysis to generate a descriptive overview of movement and weight-bearing asymmetries of owner-sound riding horses. 235 horses were subjectively assessed in a field study, and the owner's perception of their horse's orthopedic health was recorded through an online survey. 69 horses were re-evaluated by gait analysis at an equine hospital. During trot on an instrumented treadmill, the gait was scored by a veterinarian using lameness grades from 0/5 (sound) to 3/5 (moderate lameness visible at trot). Movement asymmetry of the head (HDmin) and pelvis (PDmin) and weight-bearing asymmetry were quantified simultaneously. The prevalence of subjectively scored lameness grade ≥2/5 in one or more limbs was 55% during study part 1 and 74% during study part 2. Movement asymmetry of the head and/or pelvis exceeding HDmin ≥12 mm and/or PDmin ≥6 mm was found in 57% of the horses. 58% showed weight-bearing asymmetries between contralateral front and/or hind limbs of ≥3% body mass. Gait analysis showed considerable variability of movement and weight-bearing asymmetry values, sometimes independent of the clinical lameness grade, especially in the forehand. Several horses with lameness grade ≤1/5 had asymmetry values greater than mentioned thresholds. The analysis of movement and weight-bearing asymmetry revealed that these objective variables did not necessarily act uniformly and therefore should be interpreted with caution.

Upper body movement analysis of multiple limb asymmetry in 367 clinically lame horses

BACKGROUND

Compensatory lameness is common in horses and evaluation can be challenging.

OBJECTIVES

To investigate patterns of compensatory movements in clinical cases with fore- or hindlimb lameness before and after diagnostic analgesia.

STUDY DESIGN

Retrospective clinical study.

METHODS

Multiple limb lameness of 367 horses was characterised by type (push-off, impact or mixed), limb (fore- or hindlimb in predominant lameness) and side (ipsi- or contralateral in concurrent lameness) using a body-mounted inertial sensor (BMIS). Diagnostic analgesia was performed until the percentage improvement of the vector sum in forelimb lameness and the mean difference of the maximum or minimum pelvic height (PD_max or PD_min ) in hindlimb lameness was ≥50%. Linear mixed model and post-estimation of effects were performed by contrast command with multiple comparisons adjusted by Bonferroni method. Correlation of pre- and post-analgesia of all head and pelvis asymmetry parameters was tested with Spearman's rank correlation.

RESULTS

Improvement in vector sum per mm after diagnostic analgesia in forelimb impact lameness positively correlated with decrease in PDmax in contralateral mixed lameness (0.187 mm, r = .58, P < .05). Improvement in PD_min per mm after diagnostic analgesia in hindlimb mixed and PD_max in hindlimb push-off lameness decreased vector sum in ipsilateral forelimb impact lameness by 0.570 and 0.696 mm, respectively (P < .05), with no positive correlation.

MAIN LIMITATIONS

A variety of cases with inhomogeneous distribution of lameness patterns was investigated retrospectively, therefore, it is impossible to distinguish between true multiple limb lameness and compensatory lameness in this clinical material.

CONCLUSIONS

Various asymmetry patterns of concurrent lameness were seen in horses with naturally occurring primary forelimb impact lameness with contralateral compensatory hindlimb lameness with a mixed component being the most common. In horses with hindlimb lameness, compensatory movements were seen in ipsilateral forelimbs, mostly as an ipsilateral impact lameness during straight line trot.

Adaptation strategies of horses with induced forelimb lameness walking on a treadmill

BACKGROUND

There is a paucity of research describing the gait pattern of lame horses at the walk.

OBJECTIVES

To describe the changes in motion pattern and vertical ground reaction forces (GRFz) in horses with induced forelimb lameness at the walk and compare those changes with the changes observed at the trot.

STUDY DESIGN

Experimental study.

METHODS

In 10 clinically sound Warmblood horses, moderate forelimb lameness was induced using a sole pressure model followed by trot and walk on a treadmill. Kinematic data were collected using 3D optical motion capture (OMC), and GRFz by an instrumented treadmill. Mixed models were used to compare sound baseline versus forelimb lameness (significance was set at P < .05).

RESULTS

Lameness induction significantly reduced peak GRFz on the second force peak, and vertical impulse in the lame limb. Stride and stance duration in all limbs were reduced. Lameness significantly affected the vertical movement symmetry of the head and withers. Maximum limb retraction angle, fetlock extension and protraction speed were reduced in the lame limb. Body centre of mass (COM) translation was reduced in the side-to-side direction and increased in the vertical and fore-aft directions. Several compensatory kinetic and kinematic changes were observed in the nonlame limbs. The observed changes in both kinetics and kinematics were generally smaller at walk with fewer variables being affected, compared to the trot.

MAIN LIMITATIONS

Only one degree and type of orthopaedic pain (sole pressure) was studied.

CONCLUSIONS

Compensatory strategies of forelimb lameness at the walk include alteration of several kinetic and kinematic parameters and have some specific patterns and inter-individual differences that are not seen at the trot. However, much like at the trot, head movement and forelimb vertical force symmetry seem to be the most useful parameters to detect forelimb lameness at walk.

Automatic hoof-on and -off detection in horses using hoof-mounted inertial measurement unit sensors

For gait classification, hoof-on and hoof-off events are fundamental locomotion characteristics of interest. These events can be measured with inertial measurement units (IMUs) which measure the acceleration and angular velocity in three directions. The aim of this study was to present two algorithms for automatic detection of hoof-events from the acceleration and angular velocity signals measured by hoof-mounted IMUs in walk and trot on a hard surface. Seven Warmblood horses were equipped with two wireless IMUs, which were attached to the lateral wall of the right front (RF) and hind (RH) hooves. Horses were walked and trotted on a lead over a force plate for internal validation. The agreement between the algorithms for the acceleration and angular velocity signals with the force plate was evaluated by Bland Altman analysis and linear mixed model analysis. These analyses were performed for both hoof-on and hoof-off detection and for both algorithms separately. For the hoof-on detection, the angular velocity algorithm was the most accurate with an accuracy between 2.39 and 12.22 ms and a precision of around 13.80 ms, depending on gait and hoof. For hoof-off detection, the acceleration algorithm was the most accurate with an accuracy of 3.20 ms and precision of 6.39 ms, independent of gait and hoof. These algorithms look highly promising for gait classification purposes although the applicability of these algorithms should be investigated under different circumstances, such as different surfaces and different hoof trimming conditions.

Asymmetries of horses walking and trotting on treadmill with and without rider

BACKGROUND

Left-right movement symmetry is a highly desirable characteristic in sport horses.

OBJECTIVES

This study compared movement symmetry in well-trained dressage horses in unridden and unrestrained position and ridden in a dressage frame, and investigated possible associations between gaits.

STUDY DESIGN

Experimental study.

METHODS

Seven sound, high-level dressage horses were measured at walk and sitting trot on a treadmill at several speeds under two conditions: with and without rider. Left-right differences in stance duration, stance protraction and retraction based on longitudinal hoof positions, ipsilateral limb tracking, minimum and maximum vertical positions of the dorsal spinous processes of the sixth thoracic (T6), third sacral vertebrae (S3) and wing of atlas, and vertical ground reaction forces were calculated and analysed in mixed models.

RESULTS

At walk, five body variables indicated increased asymmetry in the ridden condition compared with unridden condition: forelimb stance duration (unridden/ridden left-right differences 9 vs 13 ms; P = .008), forelimb stance protraction (P = .004), stance retraction (P = .001) and first force peak (P = .003), and hindlimb stance retraction (P = .01). At trot, six body variables were more asymmetrical in the ridden condition: forelimb stance duration (2.5 vs 3.8 ms, P = .004); hindlimb stance protraction (P < .0001) and retraction (P = .01), T6 minimum (4 vs 6 mm, P = .001), T6 maximum (9 vs 11 mm, P = .01) and S3 maximum (6 vs 12 mm, P < .001). Five variables had significant associations between asymmetries at walk and trot, but only three demonstrated a positive slope.

MAIN LIMITATIONS

A limited number of horses and riders were studied. Measurements were performed on a treadmill.

CONCLUSIONS

High-level horses moved slightly more asymmetrically when ridden in a dressage frame than in the unridden condition.

Long-term prognosis for return to athletic function after interspinous ligament desmotomy for treatment of impinging and overriding dorsal spinous processes in horses: 71 cases (2012-2017)

OBJECTIVE

To determine the long-term return to performance of horses with impinging and/or overriding dorsal spinous processes (ORDSP) treated with interspinous ligament desmotomy (ISLD) and to determine the prognostic value of radiographic and scintigraphic grades.

STUDY DESIGN

Retrospective study.

ANIMALS

Seventy-one horses with ORDSP treated with ISLD.

METHODS

Medical records were reviewed for signalment, physical examination, gait evaluation, and number of interspinous spaces treated. Preoperative radiographic and scintigraphic images were evaluated with grading scales. Follow-up was obtained with a telephone questionnaire. Prognostic value of the number of affected interspinous spaces, radiographic grading, and scintigraphic grading was tested by using a χ² test.

RESULTS

A median follow-up of 35 months (range, 8-64) was available for 56 horses. Fifty-one of 56 (91.1%) horses returned to some level of performance, with 27 of 51 (52.9%) horses achieving equivalent or higher level of performance. Achieving a lower level of performance was attributed to recurrent back pain in nine of 24 (37.5%) horses and to unassociated lameness in nine of 24 (37.5%) horses. Owners of 44 of 56 (78.6%) horses were satisfied with the postoperative performance level, and owners of 46 of 56 (82.1%) horses would recommend the procedure. None of the variables tested influenced the return to performance.

CONCLUSION

Interspinous ligament desmotomy allowed horses with ORDSP to return to some level of performance, although fewer returned to an equivalent or higher level of performance than had previously been reported.

CLINICAL SIGNIFICANCE

Interspinous ligament desmotomy allows affected horses to return to some level of performance, regardless of the severity of radiographic and scintigraphic findings.

Sensor-based equine gait analysis: more than meets the eye?

Quantitative gait analysis in the lame horse has gained in popularity, likely related to the potential to remove bias from the clinical decision-making process. Its implementation into clinical practice is, however, not without challenges. This review visits some of the challenges related to the use of thresholds and guideline values in the context of clinical decision making, as well as when applied to scientific studies based on relevant published studies: issues such as ‘normal day-to-day variation’, conformational asymmetry and the often limited number of parameters that are being quantified. Emphasis is put on outlining the basic underlying principles relating to head nod and hip hike, which are explained in the context of Newtonian mechanics associating reduced vertical acceleration of the upper body to reduced force production with the limb that is in contact with the ground during that time period. Further to quantifying what can be seen ‘by eye’, the review also visits phenomena such as asymmetries in weight bearing or pushoff and compensatory mechanisms, with emphasis on measurement of withers movement and thoughts about multilimb lameness. The review concludes with thoughts about additional parameters such as limb movement and movement of the thoraco-lumbo-sacral area, which may provide additional insights into lameness and poor performance but are at current less frequently included into clinical gait analysis in the horse.

Ground Reaction Forces: The Sine Qua Non of Legged Locomotion

Legged locomotion results from the feet pressing against the ground to generate ground reaction forces (GRFs) that are responsible for moving the body. By changing limb coordination patterns and muscle forces, the GRFs are adjusted to allow the horse to move in different gaits, speeds, and directions with appropriate balance and self-carriage. This article describes the typical GRF patterns in each gait, the adaptations that produce turning, and the GRF patterns used to unload the painful limb when the horse is lame. The intent is to provide information that is of practical interest and value to equine scientists rather than being a comprehensive review of the topic.

Biomechanical findings in horses showing asymmetrical vertical excursions of the withers at walk

The walk and trot are inherently symmetrical gaits, making them potentially suitable for the detection of left-right asymmetries. The aims of this study were to describe asymmetrical vertical excursions of the withers at walk in non-lame high-level dressage horses and to seek associations between these asymmetric movements and other kinematic variables and vertical ground reaction forces (vGRFs). Seven dressage horses, judged clinically as being sound, walked unridden and unrestrained on a treadmill with an integrated force measuring system (480 Hz), from which spatiotemporal and vGRF variables were extracted. Markers were tracked by 12 infrared cameras (240 Hz). The vertical position of the sixth thoracic vertebra (T6), limb protraction and retraction distances throughout stance, and global limb lengths were determined. Contralateral trial-mean differences were calculated, including difference in T6 minimum vertical position between contralateral steps (T6minDiff). Mixed models were used to study associations between symmetry parameters. Trial-mean T6minDiff ranged between 0.3–23 mm. Of the seven horses, five consistently dropped the withers more in early left forelimb stance, one was fairly symmetrical, and one dropped the withers more in early right forelimb stance. Comparisons between contralateral limbs showed the following associations. The forelimb that was retracted when T6min was lowest showed greater retraction at toe-off (1 mm increase predicted 0.17 mm T6minDiff increase) and shorter stance duration (1 ms decrease predicted 0.3 mm T6minDiff increase). The hind limb that was in midstance when T6min was lowest showed a greater range of motion during the stance phase (1 mm increase in protraction or retraction predicted 0.2 mm T6minDiff increase). The haunches were displaced away from the side of the forelimb that was protracted when T6min was lowest (1 mm lateral shift predicted 0.07 mm T6minDiff increase). Forelimb and hind limb vGRF parameters were non-significant. Asymmetry of vertical withers movement in horses assessed as being sound at trot was related to a complex pattern of asymmetries in spatiotemporal variables throughout the stride cycle rather than to vertical load redistribution between the forelimbs. This suggests that the asymmetry may be due to inherent laterality rather than weight-bearing lameness.

Kinetics of individual limbs during level and slope walking with a unilateral transtibial bone-anchored prosthesis in the cat

Ongoing animal preclinical studies on transcutaneous bone-anchored prostheses have aimed to improve biomechanics of prosthetic locomotion in people with limb loss. It is much less common to translate successful developments in human biomechanics and prosthetic research to veterinary medicine to treat animals with limb loss. Current standard of care in veterinary medicine is amputation of the whole limb if a distal segment cannot be salvaged. Bone-anchored transcutaneous prostheses, developed for people with limb loss, could be beneficial for veterinary practice. The aim of this study was to examined if and how cats utilize the limb with a bone-anchored passive transtibial prosthesis during level and slope walking. Four cats were implanted with a porous titanium implant into the right distal tibia. Ground reaction forces and full-body kinematics were recorded during level and slope (±50%) walking before and 4-6 months after implantation and prosthesis attachment. The duty factor of the prosthetic limb exceeded zero in all cats and slope conditions (p < 0.05) and was in the range of 45.0-60.6%. Thus, cats utilized the prosthetic leg for locomotion instead of walking on three legs. Ground reaction forces, power and work of the prosthetic limb were reduced compared to intact locomotion, whereas those of the contralateral hind- and forelimbs increased (p < 0.05). This asymmetry was likely caused by insufficient energy generation for propulsion by the prosthetic leg, as no signs of pain or discomfort were observed in the animals. We concluded that cats could utilize a unilateral bone-anchored transtibial prosthesis for quadrupedal level and slope locomotion.

Alterations in body lean angle in lame horses before and after diagnostic analgesia in straight lines in hand and on the lunge

Altered body lean has been subjectively observed during lungeing in lame horses. The objectives were to quantify the influence of lameness on body lean in trot on the lunge and to investigate the influence of improvement in lameness on the differences in body lean between reins. Thirteen lame horses were trotted in straight lines and lunged on a 10m-diameter circle on both reins before and after lameness was subjectively substantially improved by diagnostic analgesia. A global position system-aided inertial measurement unit attached to the tubera sacrale quantified body lean. Differences between reins in body lean before and after diagnostic analgesia were calculated and means were determined. Five and eight horses had unilateral and bilateral hindlimb lameness, respectively. Two of five horses with unilateral and three of eight horses with bilateral lameness leaned more on the rein with the lame or lamer hindlimb on the inside of the circle (difference between reins 5-8°). Two of five horses with unilateral and two of eight horses with bilateral lameness leaned more on the rein with the lame or lamer hindlimb on the outside of the circle (4-10°). Four horses, one with unilateral and three with bilateral lameness, had only 1° difference in body lean angle between left and right reins. When lameness was improved by diagnostic analgesia, the body lean changed significantly towards similar leaning on left and right reins (mean angle changed from 8.8° to 10.0° (P=0.03) on one rein and 13.4° to 10.8° (P=0.002) on the other rein). It was concluded that body lean becomes more symmetrical between reins after improvement in lameness using diagnostic analgesia.

Effect of a unilateral hind limb orthotic lift on upper body movement symmetry in the trotting horse

In trotting horses, movement asymmetry is associated with ground reaction force asymmetry. In humans, limb length differences influence contralateral force production. Here we investigate whether horses, in immediate reaction to limb length changes, show movement asymmetry adaptations consistent with reported force differences. Aim of this study was to quantify pelvic and compensatory head and withers movement asymmetry as a function of limb length changes after application of orthotic lifts. In this experimental study movement asymmetry of eleven trotting horses was calculated from vertical displacement of poll, withers, sacrum and left and right tuber coxae with inertial sensors. Horses were assessed in-hand under 5 conditions (all with hind limb boots): without orthotic lifts, and with a 15mm or 30mm orthotic lift applied to the left hind or right hind. A linear mixed model investigated the influence of orthotic lift condition (P<0.05, pairwise posthoc Bonferroni correction). Pelvic movement asymmetry showed increased pelvic downward movement during stance of the shorter limb and increased pelvic upward movement during and after stance of the longer limb (P<0.001) with asymmetry changes of 3-7mm (4-10mm) for 15mm (30mm) lifts. Hip hike (tuber coxae movement asymmetry) was unaffected (P = 0.348). Head and withers movement asymmetry were affected less consistently (2 of 3 respectively 1 of 3 head or withers parameters). The small sample size of the study reduced generalizability, no direct force measurements were conducted and only immediate effects of orthotic lifts were assessed with no re-assessments days or weeks after. Conclusions about mechanical consequences (weight bearing, pushoff) are based on published movement-force associations. Pelvic movement asymmetry with an artificial change in limb length through application of an orthotic lift indicates increased weight support with the shorter limb and increased pushoff with the longer limb. This may be of relevance for the management of horses with different hoof shapes between contralateral limbs, for example some chronically lame horse.

Vertical movement symmetry of the withers in horses with induced forelimb and hindlimb lameness at trot

Background

The main criteria for lameness assessment in horses are head movement for forelimb lameness and pelvic movement for hindlimb lameness. However, compensatory head nod in horses with primary hindlimb lameness is a well‐known phenomenon. This compensatory head nod movement can be easily misinterpreted as a sign of primary ipsilateral forelimb lameness. Therefore, discriminating compensatory asymmetries from primary directly pain‐related movement asymmetries is a prerequisite for successful lameness assessment.

Objectives

To investigate the association between head, withers and pelvis movement asymmetry in horses with induced forelimb and hindlimb lameness.

Study design

Experimental study.

Methods

In 10 clinically sound Warmblood riding horses, forelimb and hindlimb lameness were induced using a sole pressure model. The horses were then trotted on a treadmill. Three‐dimensional optical motion capture was used to collect kinematic data from reflective markers attached to the poll, withers and tubera sacrale. The magnitude and side (left or right) of the following symmetry parameters, vertical difference in minimum position, maximum position and range‐up were calculated for head, withers, and pelvis. Mixed models were used to analyse data from induced forelimb and hindlimb lameness.

Results

For each mm increase in pelvic asymmetry in response to hindlimb lameness induction, withers movement asymmetry increased by 0.35–0.55 mm, but towards the contralateral side. In induced forelimb lameness, for each mm increase in head movement asymmetry, withers movement asymmetry increased by 0.05–0.10 mm, in agreement with the head movement asymmetry direction, both indicating lameness in the induced forelimb.

Main limitations

Results must be confirmed in clinically lame horses trotting overground.

Conclusions

The vertical asymmetry pattern of the withers discriminated a head nod associated with true forelimb lameness from the compensatory head movement asymmetry caused by primary hindlimb lameness. Measuring movement symmetry of the withers may, thus, aid in determining primary lameness location.

The development of hoof balance and landing preference in the post-natal period

Background

Foals can follow the herd within hours of birth, but it has been shown that kinetic gait parameters and static balance still have to mature. However, development of dynamic balance has not been investigated.

Objectives

To objectively quantify landing and pressure pattern dynamics under the hoof during the first half year of life.

Study design

Prospective, cohort study performed at a single stud farm.

Methods

Pressure plate measurements at walk and trot from ten Dutch warmblood foals during the first 24 weeks of life were used to quantify toe‐heel and medial‐lateral hoof balance asymmetry indexes and to determine preferred landing strategy. Concurrently, radiographs of the tarsocrural and femoropatellar joints were taken at 4–6 weeks and after 6 months to check for osteochondrosis. A linear mixed model was used to determine the effects of time point, limb pair (front/hind), side (left/right) and osteochondrosis status of every foal.

Results

At 25% of stance duration at walk, front limbs were more loaded in the heel region in weeks 6–20 (P≤0.04), the medial‐lateral balance was more to the lateral side from week 6 onwards at both walk and trot (P≤0.04). Landing preference gradually changed in the same directions. Variability in pressure distribution decreased over time. (Subclinical) osteochondrosis did not influence any of the measured parameters.

Main limitations

This study is limited by the relatively small sample size only containing one breed from a single stud farm.

Conclusions

Dynamic hoof balance in new‐born foals is more variable and less oriented towards the lateral side of the hoof and to the heel than in mature horses. This pattern changes gradually during the first weeks of life. Knowledge of this process is essential for the clinician when considering interventions in this area in early life.

A simple method of equine limb force vector analysis and its potential applications

BACKGROUND

Ground reaction forces (GRF) measured during equine gait analysis are typically evaluated by analyzing discrete values obtained from continuous force-time data for the vertical, longitudinal and transverse GRF components. This paper describes a simple, temporo-spatial method of displaying and analyzing sagittal plane GRF vectors. In addition, the application of statistical parametric mapping (SPM) is introduced to analyse differences between contra-lateral fore and hindlimb force-time curves throughout the stance phase. The overall aim of the study was to demonstrate alternative methods of evaluating functional (a)symmetry within horses.

METHODS

GRF and kinematic data were collected from 10 horses trotting over a series of four force plates (120 Hz). The kinematic data were used to determine clean hoof contacts. The stance phase of each hoof was determined using a 50 N threshold. Vertical and longitudinal GRF for each stance phase were plotted both as force-time curves and as force vector diagrams in which vectors originating at the centre of pressure on the force plate were drawn at intervals of 8.3 ms for the duration of stance. Visual evaluation was facilitated by overlay of the vector diagrams for different limbs. Summary vectors representing the magnitude (VecMag) and direction (VecAng) of the mean force over the entire stance phase were superimposed on the force vector diagram. Typical measurements extracted from the force-time curves (peak forces, impulses) were compared with VecMag and VecAng using partial correlation (controlling for speed). Paired samples t-tests (left v. right diagonal pair comparison and high v. low vertical force diagonal pair comparison) were performed on discrete and vector variables using traditional methods and Hotelling's T2 tests on normalized stance phase data using SPM.

RESULTS

Evidence from traditional statistical tests suggested that VecMag is more influenced by the vertical force and impulse, whereas VecAng is more influenced by the longitudinal force and impulse. When used to evaluate mean data from the group of ten sound horses, SPM did not identify differences between the left and right contralateral limb pairs or between limb pairs classified according to directional asymmetry. When evaluating a single horse, three periods were identified during which differences in the forces between the left and right forelimbs exceeded the critical threshold (p < .01).

DISCUSSION

Traditional statistical analysis of 2D GRF peak values, summary vector variables and visual evaluation of force vector diagrams gave harmonious results and both methods identified the same inter-limb asymmetries. As alpha was more tightly controlled using SPM, significance was only found in the individual horse although T2 plots followed the same trends as discrete analysis for the group.

CONCLUSIONS

The techniques of force vector analysis and SPM hold promise for investigations of sidedness and asymmetry in horses.

Repeatability of gait analysis measurements in Thoroughbreds in training

BACKGROUND

With the view of implementing gait symmetry measurements in Thoroughbreds in training for early detection of injuries, repeatability of inertial measurement unit (IMU) gait parameters needs to be established.

OBJECTIVES

To assess the variation of head and pelvis movement symmetry in Thoroughbreds in training.

STUDY DESIGN

Repeated observations in horses in race training.

METHODS

Daily and weekly repeat gait assessments were conducted in 14 Thoroughbreds equipped with IMUs on poll, sacrum and right (RTC) and left (LTC) tuber coxae. Gait was assessed in trot, in-hand, on a level concrete surface. Difference between vertical displacement minima and maxima and range of motion (ROM) were obtained. Ranges containing 50% (median), 75, 90 and 95% of absolute daily and weekly differences were calculated and intraclass correlation coefficients (ICC) calculated for daily and weekly repeats.

RESULTS

Median absolute daily differences ranged from 4 to 7 mm and median weekly differences from 4 to 8 mm. 90% of daily differences were between 9 and 16 mm and 90% of weekly differences between 11 and 19 mm. ICC values were found on average across sensors and gait parameters as 0.73 (ranging from 0.40 to 0.92 across parameters) for daily repeats and as 0.65 (0.27 to 0.91) for weekly repeats.

MAIN LIMITATIONS

Horses were of varying training and movement asymmetry levels, and no veterinary lameness examination was conducted.

CONCLUSIONS

Daily and weekly repeat gait assessments in this group of Thoroughbreds in training show lower ICC values than previously reported from within-day repeats in horses during lameness examinations. We recommend conducting repeatability studies for specific groups of horses when planning long-term studies aiming at identifying horses at risk of injury.

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

BACKGROUND

Horses 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.

OBJECTIVES

To document head, withers and pelvic movement asymmetry and timing differences in horses with naturally occurring gait asymmetries.

STUDY DESIGN

Retrospective analysis of gait data.

METHODS

Head, 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.

RESULTS

The 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 LIMITATIONS

The clinical lameness status of the horses was not investigated.

CONCLUSION

In 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.

Objective assessment of the compensatory effect of clinical hind limb lameness in horses: 37 cases (2011-2014)

OBJECTIVE To characterize and describe the compensatory load redistribution that results from unilateral hind limb lameness in horses. DESIGN Retrospective case series. ANIMALS 37 client-owned horses. PROCEDURES Medical records were reviewed to identify horses with unilateral hind limb lameness that responded positively (by objective assessment) to diagnostic local anesthesia during lameness evaluation and that were evaluated before and after diagnostic local anesthesia with an inertial sensor-based lameness diagnosis system. Horses were grouped as having hind limb lameness only, hind limb and ipsilateral forelimb lameness, or hind limb and contralateral forelimb lameness. Measures of head and pelvic movement asymmetry before (baseline) and after diagnostic local anesthesia were compared. The effect of group on baseline pelvic movement asymmetry variables was analyzed statistically. RESULTS Maximum pelvic height significantly decreased from the baseline value after diagnostic local anesthesia in each of the 3 lameness groups and in all horses combined. Minimum pelvic height significantly decreased after the procedure in all groups except the hind limb and contralateral forelimb lameness group. Head movement asymmetry was significantly decreased after diagnostic local anesthesia for horses with hind limb and ipsilateral forelimb lameness and for all horses combined, but not for those with hind limb lameness only or those with hind limb and contralateral forelimb lameness. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that hind limb lameness can cause compensatory load redistribution evidenced as ipsilateral forelimb lameness. In this population of horses, contralateral forelimb lameness was not compensatory and likely reflected true lameness. Further studies are needed to investigate the source of the contralateral forelimb lameness in such horses.

Alterations in thoracolumbosacral movement when pain causing lameness has been improved by diagnostic analgesia

Lameness, thoracolumbosacral pain and reduced range of motion (ROM) often coexist; better understanding of their relationship is needed. The objectives were to determine if thoracolumbosacral movement of horses changes when pain causing lameness is improved by diagnostic analgesia. We hypothesised that reduction of lameness will increase ROM of the thoracolumbosacral region. Thirteen horses with different types of hind limb lameness were trotted in straight lines and lunged on a 10m diameter circle on left and right reins before and after lameness was subjectively substantially improved by diagnostic analgesia. Inertial sensor data were collected from the withers, thirteenth (T13) and eighteenth thoracic (T18) vertebrae, third lumbar (L3) vertebra, tubera sacrale (TS), left and right tubera coxae. ROM of flexion-extension, axial rotation, lateral bending, dorsoventral, lateral-lateral motion and vertical movement symmetry were quantified at each thoracolumbar site. Hiphike difference (HHD), maximum difference (MaxDiff) and minimum difference (MinDiff) for the pelvic sensors were measured. Percentage changes for before and after diagnostic analgesia were calculated; mean±standard deviation (SD) or median [interquartile range] were determined. Associations between the change in pelvic versus thoracolumbar movement symmetry after each local analgesic technique were tested. After resolution of lameness, HHD decreased by 7% [68%] (P=0.006). The MinDiff decreased significantly by 33% [61%] (P=0.01), 45±13% (P=0.005) and 52±23% (P=0.04), for TS, L3 and T18, respectively. There was significantly increased ROM in flexion-extension at T13, in axial rotation at T13, T18, L3 and in lateral-lateral ROM at L3. Thoracolumbosacral asymmetry and reduced ROM associated with lameness were both altered immediately by improvement in lameness using diagnostic analgesia.

Validation of distal limb mounted inertial measurement unit sensors for stride detection in Warmblood horses at walk and trot

Background

Inertial measurement unit (IMU) sensor‐based techniques are becoming more popular in horses as a tool for objective locomotor assessment.

Objectives

To describe, evaluate and validate a method of stride detection and quantification at walk and trot using distal limb mounted IMU sensors.

Study design

Prospective validation study comparing IMU sensors and motion capture with force plate data.

Methods

A total of seven Warmblood horses equipped with metacarpal/metatarsal IMU sensors and reflective markers for motion capture were hand walked and trotted over a force plate. Using four custom built algorithms hoof‐on/hoof‐off timing over the force plate were calculated for each trial from the IMU data. Accuracy of the computed parameters was calculated as the mean difference in milliseconds between the IMU or motion capture generated data and the data from the force plate, precision as the s.d. of these differences and percentage of error with accuracy of the calculated parameter as a percentage of the force plate stance duration.

Results

Accuracy, precision and percentage of error of the best performing IMU algorithm for stance duration at walk were 28.5, 31.6 ms and 3.7% for the forelimbs and −5.5, 20.1 ms and −0.8% for the hindlimbs, respectively. At trot the best performing algorithm achieved accuracy, precision and percentage of error of −27.6/8.8 ms/−8.4% for the forelimbs and 6.3/33.5 ms/9.1% for the hindlimbs.

Main limitations

The described algorithms have not been assessed on different surfaces.

Conclusions

Inertial measurement unit technology can be used to determine temporal kinematic stride variables at walk and trot justifying its use in gait and performance analysis. However, precision of the method may not be sufficient to detect all possible lameness‐related changes. These data seem promising enough to warrant further research to evaluate whether this approach will be useful for appraising the majority of clinically relevant gait changes encountered in practice.

The evaluation of limb symmetry indices using ground reaction forces collected with one or two force plates in healthy dogs

OBJECTIVE

To compare the variability of symmetry indices within and between days when using one and two force plates for data collection.

ANIMALS

Seventeen healthy client-owned adult dogs.

METHODS

Vertical ground reaction force data were collected in a crossover study design, with four collection sessions on two consecutive days, and then two weeks apart (days 1, 2, 15, and 16) using both 1-plate and 2-plate collection methods. Symmetry indices were calculated for limb pairs using two standard equations (SI1 and SI2). Repeated measures analysis was used to compare symmetry indices data between plate systems and days. Significance was set at p <0.05.

RESULTS

There were no significant differences between plate systems for SI1 and SI2. There were no significant differences between data collected on different days and no significant interaction effects between variables. Symmetry indices were consistently larger for ground reaction forces calculated from non-consecutive footfalls.

CONCLUSIONS

The use of two force plate systems will minimize variance caused by trial repetition and paired limb variation. When comparing SI1 to SI2, results were not significantly different. However, there were consistently higher mean values for SI1 compared with SI2 and symmetry indices were consistently larger for 1-plate systems compared to 2-plate systems for both symmetry indices.