Langzeitkontrolle der Klauengesundheit von Milchkühen in 15 Herden mithilfe des Klauenmanagers und digitaler Kennzahlen

Gegenstand und Ziel: Monitoring der Klauengesundheit über einen definierten Zeitraum mit dem Dokumentations- und Analyseprogramm Klauenmanager. Material und Methoden: Mittels Klauenmanager erfolgte eine Evaluierung der Klauendaten von 679 Kühen, die bei zwei bzw. drei Klauenpflegebesuchen in 15 Herden dokumentiert worden waren. Die Daten wurden anhand der Parameter Prävalenz der Klauenerkrankungen, ihrer Schweregrade, der Lahmheiten sowie Kuh-Klauen-Score (CCS), Farm-Klauen-Score (FCS) und Farm-Zonen-Score (FZS) analysiert und ihre zeitliche Entwicklung dargestellt. Ergebnisse: Im Mittel waren bei Besuch 1 71,9% (max. 95,0%, min. 21,1%), bei Besuch 2 72,9% (max. 100,0%, min. 12,6%) aller Kühe lahmheitsfrei. Bei den mittleren Prävalenzen der Klauenläsionen aller Betriebe standen Ballenhornfäule (BF) mit 61,8%, Weiße-Linie-Defekte (WLD) mit 37,2%, Sohlenblutungen (SB) mit 27,5%, Dermatitis digitalis (DD) mit 19,7% und chronische Reheklauen mit 10,9% im Vordergrund. In den einzelnen Herden fanden sich BF (n = 15), WLD (n = 11), SB (n = 10), akute DD (n = 4) und chronische Reheklauen (n = 3) jeweils unter den drei häufigsten Erkrankungen. Statistisch zeigte sich eine signifikante Verbesserung der Schweregrade der Klauenläsionen aller Kühe aller Herden von Besuch 1 auf Besuch 2. Der kleinste CCS (CCSmin) lag bei 0, der höchste (CCSmax) bei 276, der kleinste FCS war 6, der höchste 72. Die Längen des oberen Quartils und der oberen Antenne in der Boxplot-Graphik der CCS-Werte der Herden differierten an den jeweiligen Besuchen deutlich. In 10 Herden war die Verbesserung der CCS-Werte vom 1. zum 2. Besuch statistisch signifikant. Die Korrelationen zwischen den Locomotion-Scores und CCS-Werten erwiesen sich bei 28 (von 33) Besuchen als signifikant. Schlussfolgerung: Die Parameter FCS, Länge des oberen Quartils, Länge der oberen Antenne und FZSmax erwiesen sich neben der Prävalenz der Lahmheiten, Klauenläsionen und ihrer Schweregrade als informative Kennzahlen zum detaillierten Vergleich der Klauendaten einer Herde zu verschiedenen Zeitpunkten.

A sphere fitting approach to determine the hip joint centre of the horse

Accurate identification of the hip joint centre (HJC) is crucial for the correct estimation of knee and hip joint loads and kinematics, which is particularly relevant in orthopaedic surgery and musculoskeletal modelling. Several methods have been described for calculation of the HJC in humans, however, no studies have used these methods in the horse despite a similar need for improved evaluation of hip joint biomechanics in rehabilitation and musculoskeletal modelling. This preliminary study uses the commonly used functional method (least-squares sphere fit) to determine the HJC in three equid cadavers. Bone pins with reflective markers attached were drilled into the tuber coxae (TC), tuber ischium (TI), tuber sacrale (TS), greater trochanter (GT), third trochanter (TT) and lateral femoral condyle (FC) of the uppermost limb of the cadavers positioned in lateral recumbency. Three repetitions of passive movements consisting of pro-and retraction, ab- and adduction and circumduction were performed. The HJC was calculated using a least-squares sphere fitting method and presented as a distance from the TC based on a percentage of the TC to TI vector magnitude. Mean (± standard deviation) of the HJC is located 52.4% (± 3.9) caudally, 0.2% (± 6.5) dorsally, and 19.8% (± 4.2) medially from the TC. This study is the first to quantify the HJC in horses ex vivo using a functional method. Further work (in vivo and imaging) is required to validate the findings of the present study.

Vertical force distribution in the paws of sound Labrador retrievers during walking

In contrast to gait analysis in humans, where pedobarography is an integral part of biomechanical studies, veterinary researchers have rarely investigated vertical force distribution (VFD) in the paws of dogs. The aim of this study was to investigate the VFD of peak of vertical force (PFz), vertical impulse (IFz) and time of occurrence of PFz during stance phase (TPFz) in 20 sound, adult Labrador retrievers walking normally on a pressure plate. A technique was used that divided the canine paw prints into quadrants. A general linear model was introduced to investigate the effects of forelimbs/hindlimbs, body side, and medial/lateral and cranial/caudal quadrants on VFD as they related to the total force (sum of all PFz/IFz values). For PFz and IFz, there were significantly greater effects on VFD in the lateral quadrants compared to the medial quadrants, respectively (6.49 ± 2.56% vs. 6.01 ± 2.60% and 6.62 ± 3.06% vs. 5.88 ± 3.21%; P < 0.001), in the forelimbs compared to the hindlimbs (8.02 ± 2.13% vs. 4.48 ± 1.61% and 8.02 ± 2.83% vs. 4.48 ± 2.36%; P < 0.001), and in the cranial quadrants compared to the caudal quadrants (7.87 ± 2.09% vs. 4.63 ± 1.93% and 8.57 ± 2.17% vs. 3.88 ± 1.98%; P < 0.001). The cranial/caudal ratio was higher in the hindlimbs than in the forelimbs (PFz: 2.10 ± 0.45 vs. 1.65 ± 0.32; P = 0.001; and IFz: 3.35 ± 0.80 vs. 2.04 ± 0.46; P < 0.001). The TPFz was reached earlier in the hindlimbs than in the forelimbs (46.86 ± 19.16% vs. 54.08 ± 19.62%; P < 0.001) and in the caudal quadrant than in the cranial quadrant (32.57 ± 5.77% vs. 68.37 ± 10.01%; P < 0.001). These data from sound Labrador retrievers could be used as a basis for future research investigating orthopedically- and/or neurologically-impaired animals.

[Monitoring of dairy cow claw health status in 15 herds using the computerised documentation program Claw Manager and digital parameters]

OBJECTIVE

Monitoring of claw health over a defined period using the digital documentation and analysis program Claw Manager.

MATERIAL AND METHODS

Data from 679 cows were documented with the Claw Manager during routine functional claw trimming on 15 dairy farms that were visited two or three times. The data of these 33 visits were analysed for the following parameters: prevalence of claw lesions, of their severity scores and of lameness as well as the Cow Claw Score (CCS), the Farm Claw Score (FCS) and the Farm Zone Score (FZS). Their chronological progression was shown using boxplot graphs.

RESULTS

Mean prevalence of all lame free cows was 71.9% at visit 1 (max. 95.0%, min. 21.1%) and 72.9% at visit 2 (max. 100.0%, min. 12.6%). The mean prevalence of claw lesions in all 15 herds was 61.8% for heel horn erosion (HHE), followed by white line lesions (WLL, 37.2%), sole haemorrhages (SH, 27.5%), acute and chronic stages of digital dermatitis (DD, 19.7%) and chronic laminitic claws (10.9%). In individual herds HHE (n = 15), WLL (n = 11), SH (n = 10), acute DD (n = 4) and chronic laminitic claws (n = 3) were consistently among the three most frequently observed lesions. A statistically significant improvement was found for the severity scores of the claw lesions of all cows from visit 1 to visit 2. The CCS ranged from 0 (CCS min) to 276 (CCS max), the FCS ranged from 6 to 72. The length of the upper quartiles and the length of the upper whiskers in the boxplot graphs of the CCS values of the herds at the various visits varied widely. The CCS of the cows of ten herds improved significantly from visit 1 to visit 2. Locomotion scores and CCS were significantly correlated on 30 of 33 visits.

CONCLUSION

The parameters FCS (median of all CCS values of a herd), length of the upper quartiles, length of the upper whiskers in the boxplot graphs FZS max, the prevalence of lameness and of claw lesions, and their severity scores proved to be very informative for a detailed comparison of claw data of herds over subsequent visits.

The jump shot - a biomechanical analysis focused on lateral ankle ligaments

Handball is one of the top four athletic games with highest injury risks. The jump shot is the most accomplished goal shot technique and the lower extremities are mostly injured. As a basis for ankle sprain simulation, the aim of this study was to extend the ankle region of an existing musculoskeletal full-body model through incorporation of three prominent lateral ankle ligaments: ligamentum fibulotalare anterius (LFTA), ligamentum fibulotalare posterius (LFTP), ligamentum fibulocalcaneare (LFC). The specific objective was to calculate and visualise ligament force scenarios during the jumping and landing phases of controlled jump shots. Recorded kinematic data of performed jump shots and the corresponding ground reaction forces were used to perform inverse dynamics. The calculated peak force of the LFTA (107 N) was found at maximum plantarflexion and of the LFTP (150 N) at maximum dorsiflexion. The peak force of the LFC (190 N) was observed at maximum dorsiflexion combined with maximum eversion. Within the performed jump shots, the LFTA showed a peak force (59 N to 69 N) during maximum plantarflexion in the final moment of the lift off. During landing, the force developed by the LFTA reached its peak value (61 N to 70 N) at the first contact with the floor. After that, the LFTP developed a peak force (70 N to 118 N). This model allows the calculation of forces in lateral ankle ligaments. The information obtained in this study can serve as a basis for future research on ankle sprain and ankle sprain simulation.

A preliminary modelling study on the equine cervical spine with inverse kinematics at walk

REASON FOR PERFORMING STUDY

The motion of the atlanto-occipital, cervical vertebral and cervicothoracic joints play an important role in equestrian sports and they are also common sites for lesions limiting performance in horses.

OBJECTIVES

To calculate inverse kinematics based on cervical vertebral motion and to develop a model close to the measured neck movements.

MATERIALS AND METHODS

Measurements were recorded in 6 horses without neck pain. Reflective markers were placed on both cristae facialis, both sides of cervical vertebra 1, 3 and 6 on the withers and hooves. The neck model was reconstructed from CT scans of the osseus structures and was developed in SIMM (Software for Interactive Musculoskeletal Modelling). Inverse kinematics calculation was done in OpenSim. Three degrees of freedom: Flexion-extension (FE), axial rotation (AR) and lateral bending (LB) were considered. The simulated motion was generated from the recorded motion of the skin markers. The differences in angular range of motion (ROM) of the joints were analysed using paired sample t tests.

RESULTS

From the model, the smallest FE ROM was in the C5-C6 joint (2° ± 1°) and the largest was in the C3-C4 joint (11° ± 5°). The smallest AR ROM was in the C5-C6 joint (2° ± 1°) and largest AR ROM was in the atlantoaxial joint (7° ± 2°). The smallest LB ROM was in the C5-C6 joint (2° ± 1°) and the largest LB ROM was in the cervicothoracic joint (18° ± 5°). There were significant differences between the ROM of joints in 51 of 168 comparisons (P < 0.05).

CONCLUSIONS

The result of the motion of each joint gives an insight into the biomechanics of the equine neck. The small FE ROM at C5-C6 illustrates the pathogenetical relevance of the model for the development of osteoarthritis. The calculated data also provides a source for inverse dynamics.

Electromyography activity of the equine splenius muscle and neck kinematics during walk and trot on the treadmill

REASONS FOR PERFORMING STUDY

Skeletal muscle activity can be concentric or eccentric, anisometric or isometric and correlation of the equine splenius muscle activity with the movement of its effector joints at walk and trot has not yet been fully characterised.

OBJECTIVE

Investigating activity of the splenius muscle together with kinematics of head and cranial neck at walk and trot.

MATERIALS AND METHODS

Kinematics and surface electromyography were measured in 6 horses (8-20-years-old, 450-700 kg) without signs of neck pain. Markers were placed on left and right crista facialis, and on left and right cervical vertebrae 1 and 3. Head and neck angle was calculated in sagittal and horizontal planes. Electrodes were placed over both splenius muscles at the level of C2. Left and right muscle activity was compared using Student t test for paired samples and correlations calculated using Pearson correlation coefficient. Significance was set at P < 0.05.

RESULTS

In all horses, maximum surface electromyography (sEMG) values at the trot were higher than at the walk. The intraindividual differences between maximum and minimum values of the EMG ranged from 45-127 mV in walk and from 154-524 mV in trot. Flexion-extension C1 angle changed by 43° in walk and 27° in trot. For each motion cycle, 2 EMG maxima were found in both gaits, occurring just prior to maximum extension of the C1 angle. Lateral bending at C1 angle changed by 16° in walk and 17° in trot and EMG reached maximum values bilaterally during maximum lateral bending at walk.

CONCLUSIONS

The splenius muscle reaches maximum activity at the beginning of the forelimb stance phases in trot, indicating functional stabilisation against flexion of the head and neck. Unilateral activity of the splenius muscle representing stabilisation against lateral movement was not found.

Influence of shoes with different weights on the motion of the limbs in Icelandic horses during toelt at different speeds

REASON FOR PERFORMING STUDY

Weight boots are commonly used for Icelandic horses to increase the height of the flight arc of the forelimbs in toelt.

OBJECTIVE

To show the influence of weights and toelting speed on the height of the swing phase.

MATERIALS AND METHODS

Eight Icelandic horses (mean ± s.d. 12 ± 3 years old, 369 ± 46 kg) were used. Reflecting makers were placed on the dorsal side of each hoof. The motion was collected with a kinematic system (10 cameras, 120 Hz sample rate, 1.3 Mpixels resolution). The horses were ridden in toelt by 2 experienced riders on a treadmill at 2 different speeds (2.96 m/s ± 0.30 and 4.10 m/s ± 0.32). At each speed the horses were measured wearing no boots, light boots (170 g) and heavy boots (280 g) on both fore hooves. The measurement sequence was varied between horses. A Kolmogorov-Smirnov test was carried out to test for normal distribution of data and ANOVA for repeated measurements were used to compare differences (P < 0.05).

RESULTS

The weight as well as the speed of toelt had a significant influence on the height of the flight arc. At the lower speed, the mean ± s.d. height was 163 ± 55 mm, whereas at the higher speed the mean height was 228 ± 60 mm. The heavy weights increased the mean height at the lower speed from 152 ± 38 to 169 ± 48 mm and at the higher speed from 214 ± 60 to 245 ± 60 mm.

CONCLUSIONS

This investigation shows that Icelandic horses can be expected to show a better toelt in competitions with weights, and ridden at a higher speed. For muscle adaptation to occur, weights should therefore be used during competitions and training.

Raising heels of hind hooves changes the equine coffin, fetlock and hock joint angle: a kinematic evaluation on the treadmill at walk and trot

REASONS FOR PERFORMING STUDY

Raised heels are commonly recommended for various equine orthopaedic conditions. However, the simultaneous effect of raised heels on the different joint angles of the equine hindlimb throughout the motion cycle has not been previously evaluated.

OBJECTIVE

To document the simultaneous effect of raised heels on the joint angles of the equine hindlimb coffin, fetlock and hock joints.

METHODS

Eight sound, adult, Warmblood horses were evaluated barefoot and with a heel wedge of 8 or 16 degrees, walking and trotting on a horizontal treadmill. Markers placed on the dorsal and cranial aspect of the hindlimb were traced using a 3D high speed video system and joint angles calculated.

RESULTS

The effects of raising the hindlimb heels by 8 or 16 degrees on the angles of the hindlimb during the stance phase are a reduction of the plantar combined coffin joint and pastern joint angle, a reduction of maximum extension in the fetlock joint, and an increase in maximum hock flexion. The relation between angles did not change significantly during the course of the stance phase in the three measurement situations, with only small differences in time of occurrence of each joint angle maxima and minima.

CONCLUSIONS

Raising the heels of hind hooves increases flexion of the coffin and hock joints during the stance phases of walk and trot, and a doubling of the angle of the raised heels also doubles the effect on the joint angles investigated. Raised heels reduce the maximum extension of the fetlock joint during the the stance phase at walk and trot.

POTENTIAL RELEVANCE

This study provides evidence for the therapeutic use of raised shoes with heels in horses with pain on maximum hock extension, e.g. spavin.

Evaluation of the force acting on the back of the horse with an English saddle and a side saddle at walk, trot and canter

REASONS FOR PERFORMING STUDY

Force transmission under an English saddle (ES) at walk, trot and canter is commonly evaluated, but the influence of a side saddle (SS) on the equine back has not been documented.

HYPOTHESIS

Force transmission under a SS, with its asymmetric construction, is different from an ES in walk, trot and canter, expressed in maximum overall force (MOF), force in the quarters of the saddle mat, and centre of pressure (COP). The biomechanics of the equine back are different under a SS compared to ES.

METHODS

Thirteen horses without clinical signs of back pain ridden in an indoor riding school with both saddles were measured using an electronic saddle sensor pad. Synchronous kinematic measurements were carried out with tracing markers placed along the back in front of (withers, W) and behind the saddle (4th lumbar vertebra, L4). At least 6 motion cycles at walk, trot and canter with both saddles (ES, SS) were measured. Out of the pressure distribution the maximum overall force (MOF) and the location of the centre of pressure (COP) were calculated.

RESULTS

Under the SS the centre of pressure was located to the right of the median and slightly caudal compared to the COP under the ES in all gaits. The MOF was significantly different (P<0.01) between saddles. At walk, L4 showed significantly larger (P<0.01) vertical excursions under the ES. Under the SS relative horizontal movement of W was significantly reduced (P<0.01) at trot, and at canter the transversal movement was significantly reduced (P<0.01) . In both trot and canter, no significant differences in the movement of L4 were documented.

CONCLUSIONS AND POTENTIAL RELEVANCE

The results demonstrate that the load under a SS creates asymmetric force transmission under the saddle, and also influences back movement. To change the load distribution on the back of horses with potential back pain and as a training variation, a combination of both riding styles is suitable.

Gait pattern of the ataxic horse compared to sedated and nonsedated horses

REASONS FOR PERFORMING STUDY

Equine ataxia is routinely evaluated subjectively by clinicians; however, objective measurements of the movement and coordination of ataxic horses have not been reported.

OBJECTIVES

To document the movement pattern of ataxic horses and compare the results to the movement of neurologically sound horses with, and without, sedation.

METHODS

Seventeen ataxic horses were evaluated walking and trotting on a treadmill using a 3D high speed video system. From the horizontal movement of hoof markers the autocorrelation function (ACF) of the left forelimb and the cross correlation function (CCF) between the left forelimb and other 3 limbs (CCF foreleft/hindright [flhr], foreleft/ hindleft [flhl], foreleft/foreright [flfr]) was calculated. This resulted in a value of motion cycle consistency. The results were compared to data of 17 neurologically normal horses with, and without, sedation with detomidine. For statistical analysis the t test for independent samples was used.

RESULTS

Comparing normal (NO) and ataxic (AT) horses at the walk, highly significant differences for the ACF and for all the CCFs were documented. At the trot, ACF and CCFs flhr and flfr were significantly different in the NO and AT groups. Comparing sedated and ataxic horses, only the CCF flfr at walk and at trot were significantly different.

CONCLUSION AND POTENTIAL RELEVANCE

Ataxia is best documented and examined at the walk. At trot pendulum effect may make coordination easier for horses. The results of this study serve as basic data for evaluating questionably ataxic horses.

A pattern recognition approach for the quantification of horse and rider interactions

REASONS FOR PERFORMING STUDY

Interactions of various systems were investigated in several studies of dynamic systems, but the interactions between horse and rider have not yet been documented. These interactions include the rider's ability to control the horse, adapt to the horse and maintain both participants' body position. An optimum interaction is also adapted to the individual nature of the horse.

OBJECTIVE

To identify rider-horse interactions by means of artificial neural nets analysing the time-continuous pattern.

METHODS

Fourteen horses were measured trotting on hand, and ridden at working trot with a professional and a recreational rider using a 3D high speed video system (120 Hz)1. Angles were calculated after low pass filtering (5-20 Hz). Horse movements were described by 2D angles, angular velocities, and angular accelerations of variables of the right body side: hind and front fetlock, head, back and the summation angle of carpus, elbow, and shoulder, the summation angle of hock, stifle, and hip. Distances between the trajectories of the feature vectors in an N = 11 x 11 Kohonen map were determined and analysed by means of a cluster analysis.

RESULTS

Depending on the variables included, both rider specific as well as horse specific movement patterns could be identified. The time courses of the head angle indicate a movement pattern mainly dominated by the rider, whereas the time courses of variables of the hind fetlock and hock in most cases did not show differences between the conditions with, and without, rider. The skill of the professional rider could be documented with a higher adaptation to the horse's movement pattern.

CONCLUSION AND POTENTIAL RELEVANCE

The presented time course oriented approach provides a sensitive tool in order to quantify the interaction of rider and horse.

Influence of support boots on fetlock joint angle of the forelimb of the horse at walk and trot

REASONS FOR PERFORMING STUDY

Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting.

OBJECTIVE

To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock.

METHODS

In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome parameters, maximum extension of the fetlock joint and the moment at which maximum extension occurred in the stride cycle were determined.

RESULTS

At walk, 2 of the support boots reduced the maximum extension significantly by 0.8 and 0.9 degrees, respectively (P<0.05). Additionally, one type of boots also delayed the occurrence of maximal extension within the stride cycle. At trot, all support boots reduced maximum extension significantly by 0.56-1.44 degrees (P<0.01), and the protective boot reduced maximum extension by 0.56 degrees (P<0.05).

CONCLUSIONS AND POTENTIAL RELEVANCE

The results demonstrate the effectiveness of support boots in reducing maximum extension of the fetlock, which can be assumed to reduce tension in the suspensory apparatus and SDFT. The delay of the moment of maximal extension may be relevant in reducing dynamic forces. However, it should be noted that the long-term consequences of reduction of maximum fetlock extension are still uncertain. Such a reduction over a prolonged period might negatively affect fibre alignment in the healing tendon.

Determination of the stiffness of the equine spine

REASONS FOR PERFORMING STUDY

Mechanical properties of the equine back are the bases for realistic modelling of the back, which is recognised as an important step towards improved understanding of the pathogenesis of equine back conditions.

HYPOTHESIS

The stiffness of the equine back depends on the direction of the applied force and on the position of the spine.

METHODS

Fourteen dissected spines were tested in a tensile testing machine. In 3 different positions, simulating dorsoventral, laterolateral and dorsoventral-30 degree rotated movement, force was applied on the dorsal spinous process of T12 to reach an excursion of 4 cm in each direction. The normal distribution of the stiffness coefficients was tested with a Kolmogorov-Smirnov test and the stiffness coefficients were compared with paired t tests.

RESULTS

Mean +/- s.d. dorsoventral stiffness was 2093 +/- 611 N/m for the nonrotated spine and 2182 +/- 459 N/m for the 30 degree rotated spine. Mean laterolateral stiffness was significantly lower than dorsoventral stiffness at 1454 +/- 156 N/m.

CONCLUSIONS

The stiffness of the spine depends on the direction of loading.

POTENTIAL RELEVANCE

The stiffness of the spine under loading may be a relevant factor in the development of back disorders.

Influence of rider on lameness in trotting horses

REASONS FOR PERFORMING STUDY

Equine lameness is commonly evaluated when the horse is being ridden, but the influence of the rider on the lameness has not been documented.

OBJECTIVE

To document the effect of 2 riders of different training levels on the vertical movement of the head and croup.

METHODS

Twenty mature horses were ridden at trot by an experienced dressage rider and a novice rider, as well as trotted in hand. Kinematic measurements of markers placed on the horse's head and sacral bone were carried out. The asymmetries of the vertical head and sacral bone motion were calculated as lameness parameters and compared with paired t tests.

RESULTS

Trotting in hand, 17 horses showed forelimb lameness (1-4/10) and 13 hindlimb lameness (1-2/10). Intra-individually, 11 horses showed significant differences in forelimb lameness and 4 horses showed significant differences in hindlimb lameness when ridden. Over all horses, hindlimb lameness increased significantly under the dressage rider compared to unridden horses.

CONCLUSIONS

The presence of a rider can alter the degree of lameness; however, its influence cannot be predicted for an individual horse.

POTENTIAL RELEVANCE

In order to evaluate mild lameness, horses should be evaluated at trot both under saddle and in hand. If lameness is exacerbated, a second rider may be helpful; the level of training of the rider should be taken into consideration.

Motion pattern analysis of gait in horseback riding by means of Principal Component Analysis

As a consequence of the three interacting systems of horse, saddle, and rider, horseback riding is a very complex movement that is difficult to characterize by a limited number of biomechanical parameters or characteristic curves. Principal Component Analysis (PCA) is a technique for reducing multidimensional datasets to a minimal (i.e., optimally economic) set of dimensions. To apply PCA to horseback riding data, a "pattern vector" composed of the horizontal velocities of a set of body markers was determined. PCA was used to identify the major dynamic constituents of the three natural gaits of the horse: walk, trot, and canter. It was found that the trot is characterized by only one major component accounting for about 90% of the data's variance. Based on a study involving 13 horses with the same rider, additional phase plane analyses of the order parameter dynamics revealed a potential influence of the saddle type on movement coordination for the majority of horses.

A comparison of forces acting on the horse's back and the stability of the rider's seat in different positions at the trot

The aim of the study was to compare the stability of the rider as well as the forces acting on a horse's back with different seating positions at the trot (sitting trot, rising trot and two-point seat). The same experienced rider was mounted on 10 sound horses trotting on a treadmill. The kinetic data were recorded with an electronic pressure mat, placed under a well-fitting dressage saddle with no saddle pad. The rider used three different seating positions, each for 20 s. Right forelimb motion was used to synchronise the pressure data with the stride cycles. To determine the rider's stability, the movement of the centre of pressure (COP) along the transverse (X) and longitudinal (Y) axes was calculated. The force was taken as the sum of all segments of the pressure pad multiplied by the area of the pressure pad. The maximum force and the X- and Y-deviations were evaluated using ANOVA for repeated measures with a Bonferroni Post hoc test. The stability of the rider in the Y-direction was significantly highest in the two-point seat, followed by the rising trot and the sitting trot, respectively. In the X-direction, there was no significant difference between the three positions. The significantly highest load on the horse's back was at the sitting trot (2112 N), followed by the rising trot (2056 N) and the two-point seat (1688 N). The rider was most stable in the two-point seat while transferring the lowest load on the horse's back. The rising trot was found to be more stable and less stressful for the horse's back compared to the sitting trot.

The influence of different saddle pads on force and pressure changes beneath saddles with excessively wide trees

This study was performed to investigate the forces and pressure distribution under different saddle pads when an excessively wide saddle is used. Eighteen sound horses were ridden on a treadmill at walk and trot. The horses were equipped with a dressage saddle with an excessively wide saddle tree and four different pads (gel, leather, foam and reindeer-fur) used sequentially. For comparison, one measurement was made without a saddle pad. A pressure mat under the pad was used for the collection of kinetic data. Kinematics from the right fore-hoof were required to synchronise the data with the stride cycles. To identify any differences between measurements with and without saddle pads, the maximum overall force (MOF) and pressure distribution in longitudinal and transversal directions were calculated. The saddle pressures and MOF showed significant intra-horse effects. At walk, the foam and gel pads significantly reduced the MOF in 44.4% of cases, whereas at the trot, the gel and reindeer-fur pads significantly reduced MOF in 61.1% of subjects. The leather pad increased MOF in the highest number of horses at walk (27.8%) and trot (33.3%), although these results did not reach significance after inter-horse effects were included. The choice of a saddle pad to improve the fit of an excessively wide saddle should therefore be based on highly individual criteria for each horse.

Coordination dynamics of the horse-rider system

The authors studied the interaction between rider and horse by measuring their ensemble motions in a trot sequence, comparing 1 expert and 1 novice rider. Whereas the novice's movements displayed transient departures from phase synchrony, the expert's motions were continuously phase-matched with those of the horse. The tight ensemble synchrony between the expert and the horse was accompanied by an increase in the temporal regularity of the oscillations of the trunk of the horse. Observed differences between expert and novice riders indicated that phase synchronization is by no means perfect but requires extended practice. Points of contact between horse and rider may haptically convey effective communication between them.

Evaluation of pressure distribution under an English saddle at walk, trot and canter

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 243 +/- 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.

Influence of the load of a rider or of a region with increased stiffness on the equine back: a modelling study

REASONS FOR PERFORMING STUDY

Knowledge of load effects is crucial for the understanding of the aetiology and pathogenesis of equine back problems.

OBJECTIVE

To investigate different load scenarios of the equine back, such as being ridden or increased muscle tone, using biomechanical simulations.

METHODS

Kinetic and kinematic data of 15 sound horses and the electromyelograph of their long back muscles were recorded. A biomechanical simulation model was used for simulations under different biomechanical scenarios (ridden/unridden, localised increased stiffness) using ADAMS.

RESULTS

The vertical forces acting through a rider were: walk 3.83 N/kg, trot 5.18 N/kg and gallop 5.60 N/kg. No significant changes in transversal forces were found between ridden and unridden horses. Profound changes were seen in the torques at the segment following a region of increased stiffness: in walk, lateral peak torques increased from 342 to 1723 Nm, and in trot from 393 to 1004 Nm, and dorsoventral from 386 to 3705 Nm (walk) and 458 to 4340 Nm (trot).

CONCLUSIONS AND POTENTIAL RELEVANCE

The simulation shows that the stress of a rider is lower than that of pathological processes such as partial increased stiffness of the back. Study of revised models with improved anatomical realism might help to raise the plausibility of model results.

Influence of the rider on the variability of the equine gait

The aim of this study was to show that the motion pattern of a well-ridden horse varies less than the motion pattern of an unridden horse. In order to do so, we recorded the motion of two markers, one attached to the dorsal spinous processus of lumbar vertebra L4, the other to the right fore hoof. In total, we measured 21 horses in trot, ridden and unridden, with a fitting and with a non-fitting saddle. After breaking down the entire time series of the three-dimensional motion of the markers into their respective motion cycles, we computed a measure of motion pattern variability for the motion as well as for the derivatives (velocity and acceleration) along each of the three principal dimensions. Two of six variables (velocity and acceleration in the forward direction) displayed a significant discrimination between the ridden and the unridden case, and demonstrated the beneficial effect of a rider on the horse's motion pattern variability. Saddle fit was shown to have also an influence on motion variability: variability of two variables (velocity and of acceleration in forward direction) was significantly lower with a fitting saddle compared to a non-fitting saddle, a third variable (acceleration in the transversal direction) showed a significant difference also. This new method offers an objective evaluation of saddle fit, and a sensitive assessment of the quality of the rider in the moving horse.

Computerized detection of supporting forelimb lameness in the horse using an artificial neural network

The purpose of this study was to investigate whether artificial neural networks could be used to determine equine lameness by computational means only. The integral parts of our approach were the combination of automated signal tracking of horses on a treadmill and the computational power of artificial neural networks (ANN). The motion of 175 horses trotting on a treadmill was recorded using the SELSPOT II system for motion analysis. Two cameras traced infrared (IR) markers on the head and on the left forehoof. The motion of the head was Fourier-transformed and further processed by a multilayer feedforward ANN, which was trained to distinguish healthy from pathological gaits and to quantify the lameness. The classification was correct in 78.6% of cases. In 12% of cases the network gave contradictory results, in 5.9% the network found no answers, and in 3.5% the answers were wrong. However after proper training, it is proposed that neural networks are potentially capable of making a non-human diagnosis of equine lameness.

Evaluation of a signal-adapted filter for processing of periodic electromyography signals in horses walking on a treadmill

OBJECTIVE

To evaluate an adaptive-filter method for use in analysis of periodic electromyography (EMG) signals in which the transfer function of the filter is matched to characteristics of the signal.

ANIMALS

15 adult horses without clinical signs of back pain.

PROCEDURE

Electromyography signals of the left and right longissimus dorsi muscles, middle gluteal muscles, and triceps brachii muscle were recorded from horses walking on a treadmill, using bilaterally placed surface electrodes. A reflective marker was placed on the hoof of the left hind limb for simultaneous kinematic measurement of motion cycles. Absolute value of the measured EMG signal was convoluted by use of a filter signal equivalent to the length of 3 motion cycles. The signal-to-noise ratio (SNR) was calculated from the autocorrelation function and compared with the SNR of the unfiltered and the low-pass filtered signals.

RESULTS

The signal-adapted filter significantly increased SNR (by 7.3 dB, compared with the low-pass filter, and by 11.1 dB, compared with the unfiltered EMG signal).

CONCLUSIONS AND CLINICAL RELEVANCE

The signal-adapted filter eliminates signal parts that are not correlated to periodic motion. The method reported here improves the applicability of periodic EMG signals as a clinical tool.

The influence of lameness on equine stride length consistency

The aim of this study was to assess the influence of orthopaedic pain on the variation of stride length as a kinematic system-parameter in 21 horses with forelimb lameness. Data were collected while the horses were trotting on a treadmill during a minimum of 12 motion cycles, both before and after intra-articular or perineural anaesthesia. Stride length was assessed for each motion cycle, and the mean and standard deviation were calculated for each condition. Forelimb lameness was documented as percentage of asymmetry of vertical head movement. With significant decrease of forelimb lameness after regional anaesthesia, the SD of stride length increased significantly (+0.35%, P< 0.05). Our results show that in the presence of orthopaedic pain horses keep stride variability low, possibly because the lame horse employs an optimum compensatory mechanism to reduce the pain in the affected limb, and every deviation from this pattern increases pain.

Arthroscopic autologous osteochondral mosaicplasty for the treatment of subchondral cystic lesion in the medial femoral condyle in a horse

An 11-year-old, Hungarian half-bred stallion was presented with a history of mixed left hindlimb lameness of 6 months duration. Subchondral bone cyst of the medial femoral condyle and injury of the medial meniscus were diagnosed. Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the less weight-bearing medial border of the medial femoral trochlea of the affected limb, and transplanting them into the cyst during arthroscopy. The lameness was evaluated prior to and one year after the operation with a motion analysis system during treadmill exercise. Considerable improvement of the lameness and the clinical signs as well as successful transplantation of the grafts, and a new hard joint cartilage surface of the medial femoral condyle could be detected during follow-up arthroscopy. Osteochondral autograft transplantation seems to bee a possible alternative for treating subchondral cystic lesions of the medial femoral condyle in horses. A new technique for the surgical treatment of a subchondral cystic lesion of the medial femoral condyle in the horse is described.

Treadmill study of the range of back movement at the walk in horses without back pain

OBJECTIVE

To evaluate back movement during walking in horses.

ANIMALS

22 adult horses with no history or signs of back pain.

PROCEDURE

3-dimensional movements of markers on the hooves, head, and back were measured with a motion analysis system while the horses were walking on a treadmill. The positions of markers on the hooves, head, and the skin above the spinous processes of T5, T10, T16, L3, and 2 sacral vertebrae were recorded. From a minimum of 6 walking motion cycles/horse, marker movement and the time of occurrence of minimum and maximum marker positions within the motion cycle were determined. Angles were calculated between the markers on the head, T16, and S4 or S5 and between the markers on T5, T16, and S4 or S5.

RESULTS

Lateral back movement was maximal at L3, where it reached (mean +/- SD) 3.5 +/- 0.8% of the horses' height at the withers. Maximum dorsoventral back movement was found at the sacrum, where it reached 4.7 +/- 1.3% of the height at the withers. In the horizontal plane, the angle between T5, T16, and S4 or S5 was altered by 11 +/- 2.5 degrees during the motion cycle. In the sagittal plane, the angle between the head, T16, and S4 or S5 was altered by 7 +/- 3 degrees.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study may be used as basic kinematic reference data for evaluation of back movement in horses.

Evaluation of the EMG activity of the long back muscle during induced back movements at stance

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.

Range of back movement at trot in horses without back pain

The aim of this study was to establish basic reference data for evaluating 3-dimensional movement of the equine back at the trot. In 22 mature horses without any clinical signs of back pain, the movement of the back was measured during trotting on a treadmill with a system for motion analysis. The position of the markers placed on the head, hooves, skin above the spinous processes of T5, T10, T16, L3 and on 2 of the sacral spines was recorded. The results of all movements were expressed in percent of the horse's height at its withers. At the trot, the maximum lateral movement at the head was 1.72% (s.d. 0.75). At T5 it was 3.15% (s.d. 0.84), at T10 1.99% (s.d. 0.64), at T16 1.85% (s.d. 0.65), at L3 1.89% (s.d. 0.62), at OS1 1.89% (s.d. 0.66) and at OS2 2.21% (s.d. 0.71). The maximum dorsoventral back movement was 4.06% (s.d. 1.14) at the head, 3.93% (s.d. 0.67) at T5, 4.46% (s.d. 0.85) at T10, 4.94% (s.d. 0.77) at T16, 4.91% (s.d. 0.74) at L3, 4.55% (s.d. 0.69) at OS1 and 4.33% (s.d. 0.69) at OS2. The lateral movement of the back at trot is relatively small compared to the movement of the horse's back at stance or at walk, with the marker on T5 showing the widest lateral movement. The dorsoventral movement of the back is larger than the lateral movement, but the differences between single markers are small. The results of this study can be used as a comparison when investigating equine back pain.