Head and pelvic movement asymmetry during lungeing in horses with symmetrical movement on the straight

REASONS FOR PERFORMING STUDY: Lungeing is commonly used as part of standard lameness examinations in horses. Knowledge of how lungeing influences motion symmetry in sound horses is needed. OBJECTIVES: The aim of this study was to objectively evaluate the symmetry of vertical head and pelvic motion during lungeing in a large number of horses with symmetric motion during straight line evaluation. STUDY DESIGN: Cross‐sectional prospective study. METHODS: A pool of 201 riding horses, all functioning well and considered sound by their owners, were evaluated in trot on a straight line and during lungeing to the left and right. From this pool, horses with symmetric vertical head and pelvic movement during the straight line trot (n = 94) were retained for analysis. Vertical head and pelvic movements were measured with body mounted uniaxial accelerometers. Differences between vertical maximum and minimum head (HDmax, HDmin) and pelvic (PDmax, PDmin) heights between left and right forelimb and hindlimb stances were compared between straight line trot and lungeing in either direction. RESULTS: Vertical head and pelvic movements during lungeing were more asymmetric than during trot on a straight line. Common asymmetric patterns seen in the head were more upward movement during push‐off of the outside forelimb and less downward movement during impact of the inside limb. Common asymmetric patterns seen in the pelvis were less upward movement during push‐off of the outside hindlimb and less downward movement of the pelvis during impact of the inside hindlimb. Asymmetric patterns in one lunge direction were frequently not the same as in the opposite direction. CONCLUSIONS: Lungeing induces systematic asymmetries in vertical head and pelvic motion patterns in horses that may not be the same in both directions. These asymmetries may mask or mimic fore‐ or hindlimb lameness

The Visual Process: Immediate or Successive? Approaches to the Extramission Postulate in 13th Century Theories of Vision

Is vision merely a state of the beholder’s sensory organ which can be explained as an immediate effect caused by external sensible objects? Or is it rather a successive process in which the observer actively scanning the surrounding environment plays a major part? These two general attitudes towards visual perception were both developed already by ancient thinkers. The former is embraced by natural philosophers (e.g., atomists and Aristotelians) and is often labelled “intromissionist”, based on their assumption that vision is an outcome of the causal influence exerted by an external object upon a sensory organ receiving an entity from the object. The latter attitude to vision as a successive process is rather linked to the “extramissionist” theories of the proponents of geometrical optics (such as Euclid or Ptolemy) who suggest that an entity – a visual ray – is sent forth from the eyes to the object. The present paper focuses on the contributions to this ancient controversy proposed by some 13th-century Latin thinkers. [...

Radiological features of arterial channels in the equine third phalanx measured using a novel customized software represent changes of laminitis

To identify and measure radiolucencies at the solear margin of the distal phalanx in radiographs of healthy and laminitic hooves.Clinical records and dorsoproximal-palmarodistal radiographs of equine forelimbs with radiological diagnoses of either laminitis (n = 40, L) or navicular syndrome (n = 40, NS).Outlines of the radiolucent structures at the solar margin were drawn in ImageJ, and a customized novel plugin "Arteries Analyzer/ImageJ" was used for measurements. The diverging radiolucencies outside the terminal arc of the distal phalanx were differentiated as arterial channels (open at the solear margin) and ellipses (closed at the solear margin). Comparisons between L and NS, between distal phalanges with and without ellipses, and of arterial channels and ellipses in areas were compared using Wilcoxon and the Mann-Whitney U tests, respectively. The reliability and repeatability of the method were tested using Friedman\u27s test.Fewer arterial channels but more ellipses were identified in L than in NS. In phalanges with ellipses (n = 47), the number of ellipses and the number of arterial channels were negatively correlated (PCC -0.181, P = .224). The number of ellipses correlated positively with the severity of laminitis (PCC 0.495, P < .001; n = 80) and with the degree of rotation of the distal phalanx (PCC 0.392, P < .001; n = 80).The software tool successfully measured arterial channels and ellipses outlined by the evaluators. Results indicate that healthy arteries develop into pathological ellipses in laminitic feet. This may be used to complement the interpretation of radiographs and support clinical decision-making

The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion

Reasons for performing study: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. Objectives: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. Methods: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. Results: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2° at walk and increased by 3.3° at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9° at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7° at T13, 0.8° at T17, 0.5° at L1, 0.4° at L3 and 0.3° at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3° at T10 and 0.9° at T13) (P<0.05) during stance of the lame diagonal. Conclusions: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. Potential relevance: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness

MOTION PATTERN CONSISTENCY OF THE RIDER-HORSE SYSTEM

INTRODUCTION: Dressage riding is difficult to judge, because the aesthetics of the performance cannot be measured simply. The aim of this study was to show a method of visualizing and quantifying the harmony of the motion of a rider and a horse by evaluating their coordination. Rider and horse have a natural frequency when trotting; they can therefore be considered a system of coupled biological oscillators. The characteristics of such a system are determined by the innate and learned motion patterns, anatomy and physical condition of both participants. Any periodic motion can be described as a limit-cycleattractor in the phase space. The characteristics of an oscillator or a system of oscillators can be depicted as a phase plane diagram (PPD), which is a suitable method to visualize the characteristics (e.g., longterm behavior and limit-cycle) of a complex system, such as the ridden horse. METHODS: Twenty horses aged 4 to 22 years on different training levels were measured being ridden at trot by a professional rider and a hobby rider. The measurements were carried out from the right side, with six cameras (sample rate 120 Hz, resolution 240 x 833 points) tracing 20 reflecting spherical markers placed on the horse’s and rider’s right side. At least eight recordings of five seconds each were taken with the ExpertVision System of the Motion Analysis Corporation with the horse trotting on a 12 m long pressed sand track in an indoor riding arena. At least eight motion cycles of each rider-horse combination were analyzed. The 3-dimensional movements of the markers were used to deduce the angle between the linkages of rider’s head to rider’s back and of rider’s back to the horse’s head. Then the data were normalized to 100% of the length of the motion cycle. Angle velocity and angle acceleration were computed and from all three data-sets, scaled to 100% of the professional rider’s angle, angle velocity and angle acceleration; the trajectories in the phase-space were plotted and the lengths of the resulting vectors (LV) in the phase-space were computed. The mean and average deviation (variation of LV) of LV of every horse and rider were determined and grouped for each rider. The normal distribution of each group was tested with the Kolmogorov-Smirnov test. The Student test of paired samples and one-way analysis of variance were used to check the differences between the mean of the groups of LV and average deviation. RESULTS AND DISCUSSION: There was no significant difference in the mean of LV between the 2 riders, but there was a significant () difference in the average deviation of the LV, showing that the motion of the horse-professional rider system is more consistent than of the horse-hobby rider system. With this method the rhythm and the natural balance of the rider-horse system can be evaluated, and this information might prove a useful feedback for the education of riders

THE INFLUENCE OF THE RIDER ON THE TROTTING MOTION OF A HORSE

Introduction: The characteristics of trot, such as collection, impulsion, action of the hind quarter, the position of the head and the balance of the horse are described in the Rules of Dressage Events of the Federation Equestre International. Up to now, these characteristics were judged subjectively by dressage judges, but no objective measures have been developed to substantiate these judgments. The aim of our study was to establish measurable criteria that make possible the quantification of dressage characteristics, by comparing the motion pattern of trotting horses ridden by two riders of different skill and being led on hand. Materials and Methods: Twenty horses aged 4 to 22 years at different training levels were measured being ridden at trot by a professional rider and a hobby rider, as well as being trotted on hand. The measurements were carried out from the right side, with six cameras (sample rate 120 Hz, resolution 240 x 833 points) tracing 20 reflecting spherical markers placed on the horse’s and rider’s right side. At least eight recordings of five seconds each were taken with the ExpertVision System of Motion Analysis Corporation with the horse trotting on a 12 m long pressed sand track in an indoor riding arena. At least eight motion cycles of each rider-horse combination and of the horses being trotted on hand were analyzed. The 3-dimensional movement of the markers was calculated, and the stridelength, speed, and vertical movement of the fetlock joints were compared. The data were normalized to the trotting speed. The normal distribution of each group was tested using the Kolmogorov- Smirnov test, and the Student test of paired samples was used to check the differences between the means of the groups of the above described parameters. Results and Discussion: With the hobby rider the horses had the significantly lowest trotting speeds, the smallest stride length, the highest head position, the smallest vertical movement of the fetlock joint and the longest duration of stancephase when compared to when the horse is ridden by the professional rider and trotted on hand. Between the horse’s motion when ridden by the professional rider and trotted on hand no significant differences could be detected in the trotting speed and the duration of stance-phase, whereas significant differences were established for head position and stride length. The vertical movement of the fetlock joint did not differ significantly when ridden by the hobby rider and trotted on the hand, but both did differ significantly from the vertical movement of the fetlock joint when ridden by the professional rider. The results of this study show that some terms used by the Federation Equestre International can be translated into measurable quantities, and thus a more objective judgment of dressage may evolve