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Horse's laterality: methods of determination, genetic aspects, interaction with human handedness and the influence on horse-rider communication, horse's muscle status, sport success and risk of injury
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The aim of the present study was to investigate whether laterality test results obtained on the ground relate to laterality during riding and to examine the influence of human handedness and horse’s laterality on rein tension. The present study contained an online-survey with 686 riders and 1286 horses as well as the comparison of twelve different methods to investigate horse’s laterality on the ground and during riding between five groups of horses (6.553 horses in total) and rein tension measurements with a group of 88 warmbloods, Quarter Horses and mixed breeds (41 right-lateral, 35 left-lateral and 12 without reported laterality) with 65 riders (49 right-handed, 14 left-handed and 2 ambidextrous) in 110 rides (51 in conventional European riding and 59 in Western riding). Rein tension was analysed using Excel and linear mixed models in SPSS. The relation of different laterality test methods among each other was investigated using cross-tabulations, chi²-tests, phi and Cramer’s V, as well as Pearson-correlations. Heritability was determined using uni- and bivariate linear animal models in DMU6. Laterality test results obtained on the ground did not agree with laterality during riding. Only the rider’s assessment of their horse’s laterality and the lateral displacement of the horse’ hindquarters allowed conclusions on laterality during riding. In most populations the majority of horses had their hindquarters displaced to the right. Based on the rider’s assessment of their horse side preference for dressage tasks, no overall direction of laterality could be documented in any population. Right-lateral and ambidextrous horses were more successful overall. Heritability of the lateral displacement of the hindquarters was high in warmbloods and low to moderate level in Thoroughbreds. In dressage and show jumping there seems to be an advantage for both left-lateral and ambidextrous riders as well as left-lateral horses. A direct relation of the lateral displacement of the hindquarters to sensitive muscle trigger points could not be documented. In addition to the stability of rein tension, two aspects of symmetry (quantitative symmetry between left and right rein tension and temporal symmetry of left and right rein tension peaks) were identified that are influenced mainly by human handedness. Horse’s laterality mainly influenced the magnitude of rein tension as well as the symmetry of the inside versus the outside rein. Right-handed riders depended upon their dominant hand while trying to compensate their horse’s laterality and produced more symmetric rein tension with right-lateral horses. In contrast, left-handed riders reacted to their horse’s non-dominant side, regardless of the horse’s direction of laterality. Less rein tension was applied with a more stable and symmetric contact in Western riding compared to conventional European riding.
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... /fvets. . apparatus and nervous system are usually subsumed under the term "laterality" [see (6) for a detailed review of this topic]. The existence of laterality has been observed in many species including humans and horses for a longtime (2,(7)(8)(9)(10). ...
... Besides breed differences and genetic factors, training and handling are frequently suggested as reasons for the increased incidence of laterality in ridden horses (22,33). However, since motor-biased behavior is present even in foals, training cannot be the only mechanism (6,22,36,41,42). Similar to human handedness, a combination of genetics and other environmental factors must play a role as well (22,38,52). ...
... Although many riding theories call for a predominance of weight and leg aids, in practice, the reins are one of the main means of communication between horses and riders. Furthermore, rein signals are strongly affected by rider handedness (6). Each gait produces a specific pattern of forces applied to the horse's mouth via the reins and bit with two spikes per cycle in walk and trot and one spike per stride in canter. ...
The present study aimed to assess an agreement between established and novel methods to determine laterality and to identify the distribution of laterality in warmbloods and Thoroughbreds. Nine different methods to investigate a horses' laterality outside a riding context and during riding were compared across two groups of horses (sample A: 67 warmblood- type horses, sample B: 61 Thoroughbreds). Agreement between any two methods was assessed by calculating Cohen's kappa with McNemar's test or Bowker's Test of Symmetry, and the deviation from equal distributions was assessed with chi2-tests. Continuous variables such as rein tension parameters were analyzed using ANOVA or linear mixed models. Generally, laterality test results obtained outside a riding context did not agree with laterality during riding or among each other (Bonferroni corrected p > 0.0018). However, the rider's assessment of her/his horse's laterality allowed conclusions on rein tension symmetry (p = 0.003), and it also agreed substantially with the lateral displacement of the hindquarters (p = 0.0003), a method that was newly developed in the present study. The majority of warmbloods had their hindquarters displaced to the right (73.1%, X2 = 14.3; p < 0.0001). The pattern of lateral displacement of the hindquarters was similar in the Thoroughbred sample (right: 60.7%, left: 39.3%), but did not deviate significantly from an equal distribution (X2 = 2.8; p > 0.05). Laterality seems to be manifested in different ways, which generally are not related to each other. Attention should be paid to the desired information when selecting methods for the assessment of laterality. Horses' laterality has an impact on the magnitude and symmetry of rein tension. Matching horses and riders according to their laterality might be beneficial for the stability of rein tension and thus improve training.
... Body asymmetry in horses is complex and may have many different forms [2,17]. Generally, it is defined as the unequal anatomy of the left and right side of the body. ...
... All these findings together suggest that motor laterality is modulated by the horses' age [20], breed [21] and training [50]. Kuhnke [17] found left-biased horses to be more successful than right-biased horse in dressage and jumping disciplines. In Thoroughbred and Arabian racehorses that gallop around an oval racetrack in an anticlockwise direction and in Quarter horses that race on a straight line, the lateralisation of stride patterns has also been linked to performance [51], with a more advantageous ratio between strides and the intake of oxygen when the horses ran with a right-sided stride pattern. ...
... However, Cocq et al. [60] found increased lateral body asymmetry in terms of an increased lateral bending of the back, when the horse was ridden compared with unridden. Furthermore, Kuhnke [17] investigated whether objective measurements of motor laterality were consistent with the horse's body asymmetry as perceived by the rider but concluded that most methods were not suitable for measuring body asymmetry and motor laterality in horses under the rider. This was consistent with the findings of Rehren [2] who found that body asymmetry assessments by riders were not consistent with body asymmetry measurements on a treadmill. ...
For centuries, a goal of training in many equestrian disciplines has been to straighten the horse, which is considered a key element in achieving its responsiveness and suppleness. However, laterality is a naturally occurring phenomenon in horses and encompasses body asymmetry, motor laterality and sensory laterality. Furthermore, forcibly counterbalancing motor laterality has been considered a cause of psychological imbalance in humans. Perhaps asymmetry and laterality should rather be accepted, with a focus on training psychological and physical balance, coordination and equal strength on both sides instead of enforcing “straightness”. To explore this, we conducted a review of the literature on the function and causes of motor and sensory laterality in horses, especially in horses when trained on the ground or under a rider. The literature reveals that body asymmetry is innate but does not prevent the horse from performing at a high level under a rider. Motor laterality is equally distributed in feral horses, while in domestic horses, age, breed, training and carrying a rider may cause left leg preferences. Most horses initially observe novel persons and potentially threatening objects or situations with their left sensory organs. Pronounced preferences for the use of left sensory organs or limbs indicate that the horse is experiencing increased emotionality or stress, and long-term insufficiencies in welfare, housing or training may result in left shifts in motor and sensory laterality and pessimistic mentalities. Therefore, increasing laterality can be regarded as an indicator for insufficiencies in housing, handling and training. We propose that laterality be recognized as a welfare indicator and that straightening the horse should be achieved by conducting training focused on balance, coordination and equal strength on both sides.
Recent studies evaluating horses in training and considered free from lameness by their owners have identified a large proportion of horses with motion asymmetries. However the prevalence, type and magnitude of asymmetries when trotting in a straight line or on the lunge have not been investigated. The aim of this study was to objectively investigate the presence of motion asymmetries in riding horses in training by identifying the side and quantifying the degree and type (impact, pushoff) of forelimb and hind limb asymmetries found during straight line trot and on the lunge. In a cross-sectional study, vertical head and pelvic movement symmetry was measured in 222 Warmblood type riding horses, all without perceived performance issues and considered free from lameness by their owners. Body-mounted uni-axial accelerometers were used and differences between maximum and minimum head (HDmax, HDmin) and pelvic (PDmax, PDmin) vertical displacement between left and right forelimb and hind limb stances were calculated during straight line trot and on the lunge. Previously reported symmetry thresholds were used. The thresholds for symmetry were exceeded in 161 horses for at least one variable while trotting in a straight line, HDmin (n = 58, mean 14.3 mm, SD 7.1), HDmax (n = 41, mean 12.7 mm, SD 5.5), PDmax (n = 87, mean 6.5 mm, SD 3.10), PDmin (n = 79, mean 5.7 mm, SD 2.1). Contralateral and ipsilateral concurrent forelimb and hind limb asymmetries were detected in 41 and 49 horses, respectively. There was a linear association between the straight line PDmin values and the values on the lunge with the lame limb to the inside of the circle. A large proportion (72.5%) of horses in training which were perceived as free from lameness by their owner showed movement asymmetries above previously reported asymmetry thresholds during straight line trot. It is not known to what extent these asymmetries are related to pain or to mechanical abnormalities. Therefore, one of the most important questions that must be addressed is how objective asymmetry scores can be translated into pain, orthopedic abnormality, or any type of unsoundness.
Asymmetric forces exerted on the horse's back during riding are assumed to have a negative effect on rider–horse interaction, athletic performance, and health of the horse. Visualized on a saddle pressure mat, they are initially blamed on a nonfitting saddle. The contribution of horse and rider to an asymmetric loading pattern, however, is not well understood. The aim of this study was to investigate the effects of horse and rider asymmetries during stance and in sitting trot on the force distribution on the horse's back using a saddle pressure mat and motion capture analysis simultaneously. Data of 80 horse–rider pairs (HRP) were collected and analyzed using linear (mixed) models to determine the influence of rider and horse variables on asymmetric force distribution. Results showed high variation between HRP. Both rider and horse variables revealed significant relationships to asymmetric saddle force distribution (P <.001). During sitting trot, the collapse of the rider in one hip increased the force on the contralateral side, and the tilt of the rider's upper body to one side led to more force on the same side of the pressure mat. Analyzing different subsets of data revealed that rider posture as well as horse movements and conformation can cause an asymmetric force distribution. Because neither horse nor rider movement can be assessed independently during riding, the interpretation of an asymmetric force distribution on the saddle pressure mat remains challenging, and all contributing factors (horse, rider, saddle) need to be considered.
Bits are a common and invasive piece of equipment used in equestrian sports. A bit should be carefully chosen to suit the individual horse according to the pressure points it is willing to accept. Bit pressure is poorly understood due to a lack of accessible research instruments. The objective of this study was to describe a method to estimate pressure points from the bit on the tongue without the need for radiographs. The method employs photographic images of horses under static rein tension. Using design features on the bit, the angle at which these features press into the tongue were calculated. Ten riding school horses wearing a snaffle bridle without a noseband, were used to measure the degree to which a bit rotates under 2 kg of static rein tension for a: Turtle Top snaffle bit, French Link snaffle bit, HS single-jointed snaffle bit and ported Weymouth bit. Six dressage and eventing horses were used to measure the effect of rein tension, in 0.5 kg increments, on the degree of rotation of the bit. The bit rotated, but not significantly (P > 0.008), over the rein tensions used (up to 2kg). The reliability of the proposed method was confirmed by comparing anatomical reference lines in photographs with those in radiographs. The findings provide a reliable estimate to determine pressure points from a bit on the tongue, under rein tension without the need for invasive techniques and in the absence of technologically adequate equipment.
Helping you to apply many different diagnostic tools, Diagnosis and Management of Lameness in the Horse, 2nd Edition explores both traditional treatments and alternative therapies for conditions that can cause gait abnormalities in horses. Written by an international team of authors led by Mike Ross and Sue Dyson, this resource describes equine sporting activities and specific lameness conditions in major sport horse types. It emphasizes accurate and systematic observation and clinical examination, with in-depth descriptions of diagnostic analgesia, radiography, ultrasonography, nuclear scintigraphy, magnetic resonance imaging, computed tomography, thermography, and surgical endoscopy. Broader in scope than any other book of its kind, this edition includes a companion website with 47 narrated video clips demonstrating common forelimb and hindlimb lameness as well as gait abnormalities.
Some 30 million Americans are involved in equestrian sports. Although there is significant literature regarding catastrophic injury, there is very little literature that addresses overuse injury and its effect on rider and horse. As the horse and rider function as a unit, overuse injuries to the rider can affect the horse's training and responsiveness. Sports physicians treating riders should understand correct posture in the saddle and its alteration by muscular imbalance and injury. This review discusses common equestrian events, and common overuse injuries in recreational and competitive riders.
(C) 2004 American College of Sports Medicine
Although several genes that determine left-right asymmetry for structural syndromes such as situs inversus have been characterised in recent years (Supp, Witte, Potter, & Brueckner, 1997), there has been little progress in determining which genes or loci predispose to left-right handedness in humans. Linkage analysis has been used widely for the localisation of genes followed by their positional cloning. The complex genetics of handedness is one of the greatest problems for standard linkage analysis. Several genetic models have been proposed for the inheritance of handedness in humans. On the basis of these models, lefthandedness can be considered a common single gene trait with a high gene frequency and a non-mendelian inheritance pattern. We report here a possible strategy, using these genetic models, that can be applied for the identification for genes determining handedness in humans.
