Horizontal moment around the hoof centre of pressure during walking on right and left circles

Reasons for performing study: Recent research indicates that the digital joints experience some degree of extrasagittal motion during stance and that the moments under the hoof are asymmetric in horses walking in a straight line. On a circle, these have not been defined. Objectives: To quantify the amplitude and symmetry of horizontal twisting moments around the vertical axis through the hoof's centre of pressure on left and right circles at walk. Methods: Six Thoroughbred horses were led at walk across a Kistler force platform on a left and a right circle of 5 m radius. The resultant moment around the hoof was calculated from the 4 horizontal forces and their moment arms. Results: Five of the 6 horses exerted an internal moment around their left forehoof, and 4 exerted an internal moment around their right forehoof on the left circle. On the right circle, 5 of the 6 exerted an internal moment around the left forehoof and a weak external moment around the right forehoof. The moments under the hind hooves were bilaterally similar for right and left circles. Conclusion: Intrahorse variability in the applied moments is low, but there is some interhorse variability, especially in the forelimb moments, that indicates future studies of movements of the distal limb joints should be bilateral to account for mechanical asymmetry. Potential relevance: The finding that horizontal moments vary between forelimbs in some horses will apply to how exercise on a circle is approached, especially in rehabilitation programmes for horses with orthopaedic injury of the distal limb.     

Evaluation of discriminant analysis based on dorsoventral symmetry indices to quantify hindlimb lameness during over ground locomotion in the horse

Reasons for performing study: Advances in gait analysis techniques have led to assessment tools that can aid in detecting and quantifying lameness; here, bilateral tuberà coxae and pelvic movement during over ground locomotion are compared in order to investigate a practical method to assess hindlimb lameness in the horse. Objectives: To evaluate which parameters from anatomical landmarks on trunk and proximal hindlimbs are the best indicators of degree and side of hindlimb lameness. Methods: Fifteen horses (age 11–23 years, 6 nonlame and 9 unilaterally hindlimb lame horses 1/10 to 2/10 lame) were fitted with 4 inertial sensors: tuber sacrale, left and right tubera coxae and withers; 889 strides were collected from 6 trot trials per horse. Horses were assessed for lameness by a qualified equine orthopaedic surgeon from videos. Vertical displacement data for each sensor were used to calculate symmetry indices as well as published Fourier analysis based parameters. Linear discriminant analysis was used to determine the most discriminative parameters for 2 scenarios: grading of severity of lameness and identification of the affected limb. Results: Pelvic energy ratio gave the best indication for the degree of lameness. Directional symmetry index of the tubera coxae sensors yielded the highest discriminative power for identification of the lame limb. Conclusions and potential relevance: A good indication of the degree of hindlimb lameness can be obtained from vertical displacement data of the pelvic midline, collected from inertial sensors during over ground locomotion. The trunk mounted inertial sensor system allows for a time efficient collection of a representative database from horses with differing grade and site of lameness in a clinical setting. This is crucial for future work on a robust definition of the best parameters for lameness classification under practical conditions.     

Kinematics of saddle and rider in high‐level dressage horses performing collected walk on a treadmill

Reasons for performing the study: The kinematics of the saddle and rider have not been thoroughly described at the walk. Objective: To describe saddle and rider movements during collected walk in a group of high‐level dressage horses and riders. Methods: Seven high‐level dressage horses and riders were subjected to kinematic measurements while performing collected walk on a treadmill. Movements of the saddle and rider's pelvis, upper body and head were analysed in a rigid body model. Projection angles were determined for the rider's arms and legs, and the neck and trunk of the horse. Distances between selected markers were used to describe rider position in relation to the horse and saddle. Results: During the first half of each hindlimb stance the saddle rotated cranially around the transverse axis, i.e. the front part was lowered in relation to the hind part and the rider's pelvis rotated caudally, i.e. in the opposite direction. The rider's seat moved forwards while the rider's neck and feet moved backwards. During the second half of hindlimb stance these movements were reversed. Conclusion: The saddles and riders of high‐level dressage horses follow a common movement pattern at collected walk. The movements of the saddle and rider are clearly related to the movements of the horse, both within and outside the sagittal plane. Potential relevance: The literature suggests that the rider's influence on the movement pattern of the horse is the strongest at walk. For assessment of the horse‐rider interaction in dressage horses presented for unsatisfactory performance, evaluations at walk may therefore be the most rewarding. Basic knowledge about rider and saddle movements in well‐performing horses is likely to be supportive to this task.     

Regional differences in biochemical,biomechanical and histomorphological characteristics of the equine suspensory ligament

Reasons for performing study: Desmopathies of the suspensory ligament are relatively frequent and vary in prevalence over different anatomical regions. This variation may be because of regional differences in tissue characteristics. Objective: To characterise different regions of healthy forelimb suspensory ligaments (SLs) by means of biochemical, biomechanical and histomorphological techniques. Hypothesis: There is substantial topographical heterogeneity in the SL with respect to structural, compositional and functional characteristics. Methods: SLs were harvested from 38 limbs and used for biochemical (n = 20), biomechanical (n = 14) and histomorphological (n = 4) evaluation. Sulphated glycosaminoglycan (S‐GAG), DNA and collagen content, degree of lysyl hydroxylation and numbers of enzymatic and nonenzymatic cross‐links were determined in 7 regions of the SL: lateral and medial part of the origin (OM, OL), mid‐body (MB), axial and abaxial parts of the lateral and medial branches (ILAX, ILAB, IMAX and IMAB, respectively). Passive resistance to tensile loading was measured in 5 regions of the SL (all except OL and OM). Results: DNA content was lower in OL and OM than in all other parts. GAG content was also lower in OL and OM and highest in ILAB and IMAB. Collagen content was lower in OL/OM and highest in ILAX/IMAX. Pentosidine levels were highest in OL and significantly lower in the lateral insertion (ILAX/ILAB). There were no differences in hydroxylysylpyridinoline (HP) cross‐links or lysyl hydroxylation. Stiffness (P<0.01) and modulus of elasticity (P<0.01) were substantially higher in the MB region than in all other regions except for IMAB. Strain at failure was lower in the MB region (P<0.0001), resulting in a comparable force at rupture as in the other regions. Conclusions: Matrix composition differs to a relatively limited extent between different regions of the SL. The mid‐body of the ligament is stiffer than the branches, which have similar properties and relevance and mechanical differences between mid‐body and branches/origin may explain some use‐related differences in the prevalence of lesions.     

Effect of blindfolding on centre of pressure variables in healthy horses during quiet standing

In a standing horse the centre of pressure (COP), measured as the resultant vertical ground reaction force (GRF) of all supporting limbs, is adjusted in response to visual, vestibular and proprioceptive information. Stabilographic analysis measures balance by tracking COP movements in the horizontal plane. Loss of visual input affects stability of balance in people and has clinical implications in that instability inherent in some neurological diseases increases with the eyes closed. The objectives of this study were to evaluate the visual contribution to postural stability in horses. The hypothesis was that the magnitude and variability of postural sway variables increases when visual input is removed. Vertical GRFs were measured using two synchronized force plates and COP movements were tracked in 20 horses as they stood without visible movements of the hooves, head or neck. Three trials of 60 s duration were recorded under sighted and blindfolded conditions. Stabilographic variables (craniocaudal and mediolateral COP amplitudes, velocities and mean power frequencies and their within-trial variabilities) were calculated and compared using univariate analysis of variance.Compared with the sighted condition, blindfolding increased the magnitude and the within-trial variability of craniocaudal and mediolateral COP amplitudes and mediolateral COP velocity. The findings indicated that loss of visual input had more effect on the measured COP variables in the time domain (amplitudes, velocities) than in the frequency domain (mean power frequency). The effects of blindfolding on postural stability should be further investigated as part of a diagnostic approach to the evaluation of balance in horses with neurological impairment.     

Relationship between the forces acting on the horse's back and the movements of rider and horse while walking on a treadmill

Reasons for performing study: The exact relationship between the saddle pressure pattern during one stride cycle and the movements of horse and rider at the walk are poorly understood and have never been investigated in detail. Hypothesis: The movements of rider and horse account for the force distribution pattern under the saddle. Method: Vertical ground reaction forces (GRF), kinematics of horse and rider as well as saddle forces (FS) were measured synchronously in 7 high level dressage horses while being ridden on an instrumented treadmill at walk. Discrete values of the total saddle forces (FStot) were determined for each stride and related to kinematics and GRF. The pressure sensitive mat was divided into halves and sixths to assess the force distribution over the horse's back in more detail. Differences were tested using a one sample t test (P<0.05). Results: FStot of all the horses showed 3 peaks (P1‐P3) and 3 minima (M1‐M3) in each half‐cycle, which were systematically related to the footfall sequence of the walk. Looking at the halves of the mat, force curves were 50% phase‐shifted. The analysis of the FS of the 6 sections showed a clear association to the rider's and horse's movements. Conclusion: The saddle force distribution during an entire stride cycle has a distinct pattern although the force fluctuations of the FStot are small. The forces in the front thirds were clearly related to the movement of the front limbs, those in the mid part to the lateral flexion of the horse's spine and the loading of the hind part was mainly influenced by the axial rotation and lateral bending of the back. Potential relevance: These data can be used as a reference for comparing different types of saddle fit.     

规模化养牛场地上式青贮池设计问题探讨

青贮池建设是规模化养牛场必备并且投资较大的工程。在分析青贮工艺对青贮池建筑要求的基础上,提出了地上式青贮池建筑设计的要点,并提出牛场建设环境影响评价中应评价青贮饲料流出液对环境影响的建议。     

The effect of hoof angle variations on dorsal lamellar load in the equine hoof

Reasons for performing study: In the treatment of laminitis it is believed that reducing tension in the deep digital flexor tendon by raising the palmar angle of the hoof can reduce the load on the dorsal lamellae, allowing them to heal or prevent further damage. Objective: To determine the effect of alterations in hoof angle on the load in the dorsal laminar junction. Methods: Biomechanical finite element models of equine hooves were created with palmar angles of the distal phalanx varying from 0–15°. Tissue material relations accounting for anisotropy and the effect of moisture were used. Loading conditions simulating the stages in the stance where the vertical ground reaction force, midstance joint moment and breakover joint moment were maximal, were applied to the models. The loads were adjusted to account for the reduction in joint moment caused by increasing the palmar angle. Models were compared using the stored elastic energy, an indication of load, which was sampled in the dorsal laminar junction. Results: For all loading cases, increasing the palmar angle increased the stored elastic energy in the dorsal laminar junction. The stored elastic energy near the proximal laminar junction border for a palmar angle of 15° was between 1.3 and 3.8 times that for a palmar angle of 0°. Stored elastic energy at the distal laminar junction border was small in all cases. For the breakover case, stored elastic energy at the proximal border also increased with increasing palmar angle. Conclusions and potential relevance: The models in this study predict that raising the palmar angle increases the load on the dorsal laminar junction. Therefore, hoof care interventions that raise the palmar angle in order to reduce the dorsal lamellae load may not achieve this outcome. See also correspondence by Redden See also correspondence by Curtis     

Effect of topical atropine on intraocular pressure and pupil diameter in the normal horse eye

The objective was to determine whether topically administered 1% atropine would alter intraocular pressure. The animals studied were four healthy adult horses. Intraocular pressure and pupil diameter were measured prior to and during a 2-day period of treatment with 1% atropine sulfate. No significant changes in intraocular pressure occurred as a result of the treatment with atropine. Pupil diameter increased significantly after atropine was applied. Available information on the outflow of aqueous humor from the horse eye suggests that atropine might reduce intraocular pressure in the horse by increasing uveoscleral outflow. This could prove beneficial in the treatment of equine glaucoma. We could not confirm a significant pressure-lowering effect of atropine. It is possible, however, that a longer treatment period may be required or that atropine may have a more profound effect on glaucomatous globes.     

The difference in kinematics of horses walking, trotting and cantering on a flat and banked 10 m circle

Reasons for performing study: Locomotion adaptation mechanisms have been observed in horses, but little information is available in relation to banked and nonbanked curve locomotion, which might be important to optimise training environments. Objectives: To determine if adaptation mechanisms in horses existed when moving on a banked compared to a flat curve and whether adaptation was similar in different gaits. Methods: Eight infrared cameras were positioned on the outside of a 10 m lungeing circle and calibrated. Retroreflective markers were used to define left and right metacarpus (McIII) and proximal phalanges (P1), metatarsus (MtIII), head and sacrum. Data were recorded at 308 Hz from 6 horses lunged at walk, trot and canter on a flat and 10° banked circle in a crossover design. Measurements extracted were speed, stride length, McIII inclination, MtIII inclination, relative body inclination and duty factor. Data were smoothed with a fourth order Butterworth filter with 30 Hz cut‐off. ANOVA was used to determine differences between conditions and limbs. Results: Adaptation mechanisms were influenced by gait. At canter inside forelimb duty factor was significantly longer (P<0.05) on a flat curve compared to a banked curve; at walk this was reversed. McIII inclination, MtIII inclination and relative body inclination were significantly greater (P<0.05) at trot and canter on a flat curve, so more inward tilt was found relative to the bearing surface. Conclusion: Adaptation to curved motion is gait specific. At faster gaits it appears that horses negotiate a banked curve with limb posture closer to body posture and probably with demands on the musculoskeletal system more similar to straight canter.