Summary The kinematic patterns of head and trunk were studied in horses during induced supporting limb lameness to understand the mechanisms horses use to compensate for lameness and to evaluate different symmetry indices for their significance as lameness indicators. Using the locomotion analysis system CODA‐3 the kinematics of 11 clinically nonlame Dutch Warmblood horses were recorded while walking (1.6 m/s) and trotting (3.5 m/s) on a treadmill. A transient lameness model, evoking pressure induced pain on the hoof sole, was used to induce 3 degrees of fore‐ and hindlimb lameness. Peak vertical displacement, velocity and acceleration of head, withers, tuber sacrale and both tuber coxae were quantified at different phases of the stride. Changes in these variables due to lameness and symmetry indices calculated as quotients of the values during the lame and nonlame stance phase were analysed using a 2‐way analysis of variance. The head, withers and tuber sacrale showed a similar sinusoidal pattern in their vertical displacement, velocity and acceleration. During both fore‐ and hindlimb lameness at the trot, the vertical velocity of the trunk at impact of the lame limb decreased (P<0.05), during the lame stance phase the trunk was kept higher above the ground, maximal acceleration decreased and displacement amplitude was smaller than without lameness. Changes in movements of the head were much more expressed than movements of the withers during forelimb lameness and reversed during hindlimb lameness. At the walk, head movement patterns changed in the same way as at the trot, while withers and tuber sacrale patterns were hardly changed. Symmetry indices of all landmarks showed changes due to increasing lameness at the trot. The maximal vertical acceleration of the head and displacement amplitude of the tuber sacrale proved to be the best indicators to quantify a fore‐ and hindlimb lameness, respectively.

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Summary The ground reaction force patterns from 20 clinically sound Dutch Warmblood horses (Group A) were recorded at the normal walk. The data from four to 10 stance phases of each limb were computer averaged after normalisation to the animal's body mass and to the stance time. This analysis method allowed comparison of data from left and right fore‐ and hind‐limbs within and between horses. The left‐to‐right symmetry in the reaction force peaks of contralateral limbs of one horse exceeded 90 per cent. The time in the stance phase at which the peaks occur were even more symmetrically distributed. A characteristic force‐force diagram was constructed by plotting the longitudinal horizontal and the vertical ground reaction forces against each other; in this way the symmetry of loading of contralateral fore‐ and hindlimbs could be interpreted easily. Force plate tracings were obtained from eight horses (Group B) in three succesive years. The similarity of the tracings from a sound, well‐trained horse over that period was better than the differences between horses of the same breed.

During locomotion, 3 types of rotations are evident in the thoracolumbar vertebrae. Regional differences are observed in the shape and timing of the rotations. These differences are related to actions of the limbs. The method described here for direct measurement of vertebral column motion provides insights into the complex movements of the thoracolumbar portion of the vertebral column in trotting horses. Information on normal kinematics is a prerequisite for a better understanding of abnormal function of the vertebral column in horses.

Summary This study was undertaken to establish limb loading patterns of sound horses at the trot, to provide a data base against which results for lame horses could be compared. Ground reaction force (GRF) data were collected from 20 clinically sound Dutch Warmblood horses. The data from at least 5 stance phases of each limb were averaged after standardisation to the animal's body mass and to the stance phase duration and resulted in ‘representative’ GRF data. The symmetry in the vertical GRF peak amplitudes, impulses and the stance phase duration comparing left and right limbs exceeded 97%. By averaging the ‘representative’ GRF of the 20 horses a ‘standard’ GRF pattern of the Dutch Warmblood horse at the trot was constructed. The GRF patterns at the trot, compared with those at the walk, showed only one vertical force peak in forelimbs and hindlimbs (11.59 N/kg and 10.21 N/kg, respectively). The retardatory and propulsory forces were distributed over the forelimbs and hindlimbs in such a way that the forelimbs contributed more to retardation (peak forces 1.13 and 0.79 N/kg), and the hindlimbs more to propulsion (−0.84 and −1.17 N/kg, respectively).