Summary In order to study the mechanism of lameness transfer from fore‐ and hindlimb lamenesses 2 hypotheses were investigated. Hypothesis 1: Horses with a true supporting limb lameness in one hindlimb show a false supporting limb lameness in the ipsilateral forelimb. Hypothesis 2: Horses with a true supporting limb lameness in one forelimb show a false supporting limb lameness in the contralateral hindlimb. Fourteen horses with fore‐ or hindlimb lameness were used for this study. Each horse was measured at the trot on a treadmill with standardised speed, before and after diagnostic blocks (9 horses), or with and without induced lameness (5 horses). The head acceleration asymmetry (HAAS) and the sacrum acceleration asymmetry (SAAS) were used for quantification of fore‐ and hindlimb lameness respectively. Changes were documented by changes of the HAAS or the SAAS. In all 4 horses with a true hindlimb lameness a synchronous false lameness of the ipsilateral forelimb was documented. In 6 of 10 horses with a forelimb lameness a lameness transfer could be assessed according to hypothesis 2. The results of this study show, that horses with a true severe lameness in the forelimb show a false lameness in the contralateral hindlimb, and horses with a true hindlimb lameness show a false lameness in the ipsilateral forelimb. This indicates that the location of the truly lame limb can be deduced from the distribution of 2 lamenesses on a sagittal or diagonal axis.

As in many other sports, e.g. gymnastics, judging dressage riding is problematic because the score is subjective. The aim of this study was to find a suitable method to support education of dressage judges and training of riders with a measurable criterion for riding harmony in the trot. We analysed the consistency of motion pattern 40 different rider–horse systems in trot (20 horses and 2 riders). A high‐speed (120 Hz) 3D video system for motion analysis was used to track 20 markers taped to the horse and the rider. The angle between the line connecting the rider’s head to the rider’s back and that between the rider’s back to the horse’s head was calculated. Angular velocity and angular acceleration were derived. The lengths of the resulting vectors (LV) in the phase space were computed. Riding harmony was defined in terms of the average deviation of LV in the phase space. The results of our study showed the professional rider–horse system had a significantly (P < 0.05) lower average deviation of LV (11.5% ± 1.4) than the recreational rider–horse system (13% ± 2.8). Thus, the professional rider–horse system had a motion pattern that was more consistent than the recreational rider–horse system and this was correlated to the average dressage scores, which were significantly (P < 0.001) higher for the professional rider (mean score ± SD, 7.3 ± 2.7) than those for the recreational rider (4.1 ± 3.0). As motion pattern consistency is one of the main characteristics of riding harmony, the results of these measurements can be used for education of dressage judges and riders.

Summary Reasons for performing study: Basic information about the influence of a rider on the equine back is currently lacking. Hypothesis: That pressure distribution under a saddle is different between the walk, trot and canter. Methods: Twelve horses without clinical signs of back pain were ridden. At least 6 motion cycles at walk, trot and canter were measured kinematically. Using a saddle pad, the pressure distribution was recorded. The maximum overall force (MOF) and centre of pressure (COP) were calculated. The range of back movement was determined from a marker placed on the withers. Results: MOF and COP showed a consistent time pattern in each gait. MOF was 12.1 ± 1.2 and 24.3 ± 4.6 N/kg at walk and trot, respectively, in the ridden horse. In the unridden horse MOF was 172.7 ± 11.8 N (walk) and 302.4 ± 33.9 N (trot). At ridden canter, MOF was 27.2 ± 4.4 N/kg. The range of motion of the back of the ridden horse was significantly lower compared to the unridden, saddled horse. Conclusions and potential relevance: Analyses may help quantitative and objective evaluation of the interaction between rider and horse as mediated through the saddle. The information presented is therefore of importance to riders, saddlers and equine clinicians. With the technique used in this study, style, skill and training level of different riders can be quantified, which would give the opportunity to detect potentially harmful influences and create opportunities for improvement.

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Summary In this study we investigated the activity of the main back muscle (Musculus longissimus) by surface electromyography (EMG) during induced extension and lateral flexion at stance. Measurements were taken of 15 horses (age 5‐20 years, 450‐700 kg bwt) without signs of back pain. Reflecting markers were placed on the head, spinous processes of T5, T12, T16, L3 and on 2 of the sacral bones. The surface EMG electrodes were situated on the Musculus longissimus on both sides of the dorsal spinous processes of T12, T16 and L3. In all horses and all movements (extension, lateral flexion to the left and right), the EMG on both sides of the dorsal spinous process of T12 had the highest, and the EMG on both sides of the spinous process of L3, the lowest amplitude (30% of T12). At T16 the amplitude of the EMG signal was 60% of that at T12. There was no time shift between the EMG signals at the different locations (T12, T16, L3). There was a very high correlation between motion and amplitude of the EMG signal of extension, with correlation coefficients of 0.78 at L3, 0.80 at T16 and 0.75 at T12. The correlation of the lateral flexion between amplitude of the EMG and motion was lower, with 0.38 at L3, 0.43 at T16 and 0.39 at T12. This investigation showed that the EMG of the Musculus longissimus during spinal reflexes should be derived on both sides of T12, because this is important for the clinical use of surface EMG.