Functional Locomotor Consequences of Uneven Forefeet for Trot Symmetry in Individual Riding Horses

ABSTRACT: Left-right symmetrical distal limb conformation can be an important prerequisite for a successful performance, and it is often hypothesized that asymmetric or uneven feet are important enhancing factors for the development of lameness. On a population level, it has been demonstrated that uneven footed horses are retiring earlier from elite level competition, but the biomechanical consequences are not yet known. The objectives of this study were to compare the functional locomotor asymmetries of horses with uneven to those with even feet. Hoof kinetics and distal limb kinematics were collected from horses (n = 34) at trot. Dorsal hoof wall angle was used to classify horses as even or uneven (1.5° difference between forefeet respectively) and individual feet as flat (55°). Functional kinetic parameters were compared between even and uneven forefeet using MANOVA followed by ANOVA. The relative influences of differences in hoof angle between the forefeet and of absolute hoof angle on functional parameters were analysed using multiple regression analysis (P<0.05). In horses with uneven feet, the side with the flatter foot showed a significantly larger maximal horizontal braking and vertical ground reaction force, a larger vertical fetlock displacement and a suppler fetlock spring. The foot with a steeper hoof angle was linearly correlated with an earlier braking-propulsion transition. The conformational differences between both forefeet were more important for loading characteristics than the individual foot conformation of each individual horse. The differences in vertical force and braking force between uneven forefeet could imply either an asymmetrical loading pattern without a pathological component or a subclinical lameness as a result of a pathological development in the steeper foot

A horse’s locomotor signature: COP path determined by the individual limb

Introduction Ground reaction forces in sound horses with asymmetric hooves show systematic differences in the horizontal braking force and relative timing of break-over. The Center Of Pressure (COP) path quantifies the dynamic load distribution under the hoof in a moving horse. The objective was to test whether anatomical asymmetry, quantified by the difference in dorsal wall angle between the left and right forelimbs, correlates with asymmetry in the COP path between these limbs. In addition, repeatability of the COP path was investigated. Methods A larger group (n = 31) visually sound horses with various degree of dorsal hoof wall asymmetry trotted three times over a pressure mat. COP path was determined in a hoof-bound coordinate system. A relationship between correlations between left and right COP paths and degree of asymmetry was investigated. Results Using a hoof-bound coordinate system made the COP path highly repeatable and unique for each limb. The craniocaudal patterns are usually highly correlated between left and right, but the mediolateral patterns are not. Some patterns were found between COP path and dorsal wall angle but asymmetry in dorsal wall angle did not necessarily result in asymmetry in COP path and the same could be stated for symmetry. Conclusion This method is a highly sensitive method to quantify the net result of the interaction between all of the forces and torques that occur in the limb and its inertial properties. We argue that changes in motor control, muscle force, inertial properties, kinematics and kinetics can potentially be picked up at an early stage using this method and could therefore be used as an early detection method for changes in the musculoskeletal apparatus

Lateralised motor behaviour leads to increased unevenness in front feet and asymmetry in athletic performance in young mature Warmblood horses

Reason for performing study: Foot stance in grazing significantly influences hoof conformation and development from foal to yearling age. Objectives: To conduct a longitudinal study to establish if the relationship between motor laterality and uneven front feet persisted in 3-year-old horses at the time of studbook selection and to investigate if such laterality and unevenness might influence the horses' ability to perform symmetrically while trotting, cantering and free jumping. Methods: Seventeen clinically sound but untrained (with only minimal experience of handling) and sound Warmblood horses that had participated in a previous study were assessed as per the protocol reported. Laterality was tested in a preference test (PT) and z-values were calculated for analysis purposes. Laterality and hoof unevenness were related to both relative limb length and relative head size, while the ability to perform symmetrically was tested in free trot-canter transitions and free jumping exercises. Differences in performance between horses with and without a limb preference in the PT and those with 'uneven' and 'even' feet were tested for differences in performance metrics using Students' t test, while linearity was tested using a regression analysis (P < 0.05). Results: Significant laterality was still present in 24% of the 3-year-old horses and the relationship between laterality and uneven feet pairs was stronger than at foal and yearling stages. Horses with significant motor laterality had almost 4 times more unevenness, a smaller head and longer limbs and the relationship between body conformation and laterality was still present. There was a strong linear relation between unevenness, laterality and a bias or side preference for trot-canter transitions. However, this relationship was not significant during the free jumping exercise. Conclusion: Motor laterality and uneven feet pairs were still present and significantly related in the 3-year-old horses and both variables were also strongly related to sidedness in trot-canter transitions. Potential relevance: Warmblood studbooks should include quantitative data on laterality at the time of studbook admission as part of the selection criteria