Characteristics of Hoof Landing in Sound Horses and the Influence of Trimming and Shoeing Examined With Hoof-Mounted Inertial Sensors

The aim of the current in vivo, observational study was to investigate the effects of different hoof manipulations on landing duration (LandD), location (ICloc) and angle of initial contact (ICangle) in the front feet of horses. A novel, hoof-mounted, inertial measurement unit sensor system (IMU) was used. Ten sound, crossbred horses were fitted with an IMU sensor at the dorsal hoof wall and examined barefoot and after trimming. Additionally, the application of 120 g lateral weights and 5° medial side wedges as well as steel, aluminium, egg bar, and lateral extension shoes were tested. Horses were guided in a straight line on firm ground. The use of steel shoes increased LandD compared to barefoot and enhanced the individual ICloc in trot. Application of rolled toe shoes caused a longer LandD than use of plain shoes. None of the other modifications significantly influenced the timing or spatial variables of hoof landing. Trimming and shoeing have less impact on the landing pattern of horses than assumed in practice. Still, the use of steel shoes changes sliding properties of the hooves on firm ground and increases weight causing a longer LandD and reinforcement of the individual ICloc.

Effect of age at training initiation on hoof morphology and lameness in juvenile American Quarter Horses

BACKGROUND

Lameness, discipline, training intensity, environmental variability, and shoeing are all factors demonstrated to affect hoof loading and therefore act as adaptive stimuli to alter hoof morphology.

OBJECTIVES

To evaluate the effect of age at training initiation on hoof morphology and lameness incidence and determine if specific hoof morphology measurements correlate with lameness in juvenile American Quarter Horses.

STUDY DESIGN

Prospective cohort study.

METHODS

American Quarter Horses (n = 42; 29 two-year-olds, 13 three-year-olds) entering training were monitored for hoof morphology and lameness over 6 months (months 0, 2, 4, and 6). Hoof measurements (palmar/plantar angles, frog base width/length, toe length/angle, heel length/angle, heel and foot width, wall height/angle) from radiographs and photographs were recorded. Lameness was graded subjectively and objectively (Lameness locator®). Statistical analyses were performed with Fisher's exact test and repeated measures ANOVA with p < 0.05.

RESULTS

25/42 horses developed subclinical lameness (16/42 forelimb, 19/42 hindlimb), with 3-year-olds developing lameness more frequently compared to 2-year-olds overall (p = 0.04; 84.6 vs. 48.3%) and in forelimbs (p = 0.05; 61.5% vs. 27.6%); no difference was noted between 2- versus 3-year-olds in hindlimbs (p = 0.2; 61.5% vs. 37.9%). In lame versus sound forelimbs, 3-year-olds had decreased foot width (p = 0.03; 11.48 cm [CI 10.68-12.28] vs. 12.21 cm [CI 11.99-12.42]), decreased toe length (p = 0.03; 6.02 cm [CI 5.69-6.36] vs. 6.45 cm [CI 6.32-6.58]), shorter lateral wall height (p = 0.03; 4.64 cm [CI 4.31-4.96] vs. 5.11 cm [CI 5.03-5.2]), and shorter medial wall height (p = 0.02; 4.58 cm [CI 4.06-5.10] vs. 5.15 cm [CI 4.99-5.30]). In lame versus sound hindlimbs, horses overall (p = 0.05; 3.74, CI 3.53-3.96 vs. 3.55, CI 3.48-3.61) and 3-year-olds had longer heels p = 0.01; 3.90 cm (CI 3.5-4.3) vs. 3.50 cm (CI 3.39-3.61).

MAIN LIMITATIONS

Small sample size, lack of control group not entering training.

CONCLUSIONS

Three-year-old American Quarter Horses entering training were more likely to develop forelimb lameness than 2-year-olds. This subclinical lameness was associated with specific hoof morphology characteristics (decreased foot width, toe length, heel length, and lateral/medial wall height; greater toe angle).

Mechanical Principles of the Equine Foot

A healthy foot requires a well-balanced foot capable of shock absorption, traction, and normal proprioception. Radiographs and venograms are helpful in assessing health of the external and internal structures of the foot and in early diagnosis. Other techniques to assess foot mechanics include force plate and inertial sensors. When foot pathology ensues, early recognition and emergency mechanical treatment can improve prognosis and overall outcome. Sheared heels, under-run heels, and clubfeet are common problems that need to be corrected early. Successful management and results require he veterinarians and farriers establishing a professional, collaborative, and respectful relationship.

The influence of equine limb conformation on the biomechanical responses of the hoof: An in vivo and finite element study

Hoof conformation plays a key role in equine locomotion. Toe-in conformation is an abnormal condition characterized by inward deviation of the limb from its frontal axis. Several studies have documented differences in hoof deformation and hoof kinematics in horses with toe-in and normal hoof conformations. However, the reason behind this has yet to be understood. The present study hypothesizes that a different center of pressure (COP) path underneath the hoof is the cause of different deformation patterns and hoof kinematics in toe-in hooves. In vivo measurements and finite element (FE) analysis were conducted to test the hypothesis. A normal and a toe-in limb were considered for in vivo strain measurements. Strains were measured at three different sites on the hoof wall, and the stride characteristics were investigated using video recording. The magnitude of the minimum principal strain measured at the medial aspect of the toe-in hoof was much lower relative to the normal hoof. Furthermore, the toe-in hoof had a different movement pattern (plaiting) compared to the normal hoof. In the second study, an entire hoof model was simulated from computed tomography (CT) scans of an equine left forelimb. The Neo-Hookean hyperelastic material model was used, and the hoof was under dynamic loading over a complete stride at the trot. Two different COP paths associated with normal and toe-in conformations were assigned to the model. The FE model produced the same in vivo minimum principal strain distributions and successfully showed the different kinematics of the toe-in and normal hooves.

Dynamic evaluation of toe-heel and medio-lateral load distribution and hoof landing patterns in sound, unshod Standardbred horses with toed-in, toed-out and normal hoof conformation

Dynamic load distribution and landing patterns play an important role in equine orthopaedics. The aim of this study was to analyse dynamic load distribution and hoof landing patterns of sound Standardbreds. Twenty-four sound, unshod Standardbreds were walked and trotted over a pressure plate to obtain the peak vertical force (PVF), vertical impulse (VI) and stance time (ST) of both forelimbs. Asymmetry indices between both forelimbs were calculated and the dynamic medio-lateral and toe-heel load distribution of the forelimbs were compared between normal, toed-in and toed-out horses. The hoof landing patterns were determined on the first loaded zone. Linear mixed models and Chi-square analysis were used for statistical analysis (α = 0.05). At walk and trot, there were no significant differences in asymmetry of PVF, VI and ST between normal (n = 9/24 horses), toed-in (n = 6/24 horses), and toed-out horses (n = 9/24 horses). In both forelimbs, a flat landing (39.6% and 70.8% at walk and trot, respectively) predominated over all hoof conformations. No significant association between hoof conformation and landing pattern was observed (P > 0.05). Toed-out horses had significantly higher loading of the medial zone at the end of the stance phase at walk than normal horses (P = 0.002). No other statistically significant differences in load distribution were observed (P > 0.05). In conclusion, flat landing was more common in Standardbred horses than previously described in Warmbloods, emphasising the need for breed-specific clinical reference data and biomechanical studies. Moreover, mild deviations in hoof conformation did not necessarily affect load distribution.

The effect of routine hoof trimming on midstance regional hoof kinetics at walk

There is a lack of objective and quality evidence-based research on the effect of trimming on hoof loading at different regions of the hoof. Our objective was to measure and compare force (F), contact area (CA), contact pressure (CP) and peak contact pressure (PCP) of the dorsal vs palmar and medial vs lateral regions of the forehooves. Nine sound equine athletes were walked across a calibrated pressure plate before and after routine hoof trimming. The F, CA, CP and PCP in medial, lateral, dorsal and palmar regions were examined pre- and post-trimming, P≤0.05 was considered significant. Dorsal CP and PCP significantly increased post-trimming (P=0.039 and P=0.019, respectively). Medial F increased about 25% after trimming, but not significantly (P=0.129). These data confirm the impact of individual hoof trimming on certain aspects of the hoof midstance biomechanics.

Solar angle of the distal phalanx is associated with scintigraphic evidence of subchondral bone injury in the palmar/plantar aspect of the third metacarpal/tarsal condyles in Thoroughbred racehorses

BACKGROUND

Subchondral bone injury at the palmar/plantar aspect of the condyles of the third metacarpal/metatarsal bone (MC/MT3) commonly causes lameness and poor performance in racehorses. Injury occurs due to repetitive loading, the magnitude of which may be influenced by the position of the distal phalanx relative to the ground surface, i.e. the solar angle. The association of solar angle and injury at the palmar/plantar condyles of distal MC/MT3 therefore warrants investigation.

OBJECTIVES

Investigate the relationship between solar angle and radiopharmaceutical uptake at the palmar/plantar aspect of distal MC/MT3 on scintigraphic images of racehorses.

STUDY DESIGN

Retrospective case-controlled study.

METHODS

Scintigraphic images of Thoroughbred racehorses presented for poor performance or lameness were graded for intensity of radiopharmaceutical uptake in the palmar/plantar aspect of distal MC/MT3. Solar angle was graded (positive, neutral or negative), referring to the angle of the solar plane of the distal phalanx relative to the ground surface. Repeatability of solar angle (n = 1226 limbs) and agreement with objective radiographic evaluation (n = 52 limbs) were evaluated. Prescintigraphy performance data were collected from race records. Associations between solar angle, performance and radiopharmaceutical uptake were investigated using multivariable logistic regression.

RESULTS

Repeatability of scintigraphic solar angle grading (κ = 0.89, 95% CI 0.87-0.91) and agreement of scintigraphic and radiographic solar angle (κ = 0.88, 95% CI 0.75-0.97) were excellent. Horses that performed best prior to presentation were more likely to have both greater radiopharmaceutical uptake and a neutral/negative solar angle. When controlling for prior performance, horses with neutral/negative forelimb solar angle were twice as likely to have moderate/marked radiopharmaceutical uptake than horses with positive solar angle (P<0.02). Horses with negative hindlimb solar angle were six times more likely to have moderate/marked radiopharmaceutical uptake than horses with positive/neutral solar angle (P<0.001).

MAIN LIMITATIONS

Population bias due to preselected hospital population.

CONCLUSIONS

Both solar angle and race performance are independently associated with increased bone activity in the palmar/plantar aspect of the third metacarpal/tarsal condyles. The Summary is available in Portuguese - see Supporting Information.

The Influence of Body Mass and Height on Equine Hoof Conformation and Symmetry

Despite the likelihood that a horse's mass influences hoof morphology, empirical evidence is lacking. A clearer understanding of factors influencing hoof shape could enable prevention, or better treatment, of foot-based disorders; common causes of equine lameness. The study's aim was to investigate the relationship between horse body size, in terms of mass and height, and fore hoof dimensions. A further aim was to determine changes in the occurrence of hoof asymmetry as body size increases. Height, mass, and fore hoof dimensions; coronet band width (CBW); hoof base width (HBW); dorsal hoof wall angle (DHWA); and hoof spread (HS) of 63 riding school horses were measured within two weeks of routine shoeing. Regression analysis demonstrated positive relationships between body mass and both CBW and HBW in left and right hooves, indicating basic hoof dimensions increased as body mass increased. No relationship between horse height and hoof variables was found, suggesting mass is more influential on hoof morphology. Left and right DHWL were moderately correlated; however, paired t-test results identified a greater right than left DHWA. As left DHWA increased, left HS decreased, indicating development of a more upright hoof geometry. Both left and right HS increased as corresponding HBW increased. Both hooves tended toward a more upright conformation as horse height and body mass increased. However, asymmetries observed suggest a splayed left hoof compared to a "boxy" right hoof. Such morphological adjustments may indicate variation in horn tubule orientation in response to greater structural loading; an important consideration for hoof practitioners.

A universal approach to determine footfall timings from kinematics of a single foot marker in hoofed animals

The study of animal movement commonly requires the segmentation of continuous data streams into individual strides. The use of forceplates and foot-mounted accelerometers readily allows the detection of the foot-on and foot-off events that define a stride. However, when relying on optical methods such as motion capture, there is lack of validated robust, universally applicable stride event detection methods. To date, no method has been validated for movement on a circle, while algorithms are commonly specific to front/hind limbs or gait. In this study, we aimed to develop and validate kinematic stride segmentation methods applicable to movement on straight line and circle at walk and trot, which exclusively rely on a single, dorsal hoof marker. The advantage of such marker placement is the robustness to marker loss and occlusion. Eight horses walked and trotted on a straight line and in a circle over an array of multiple forceplates. Kinetic events were detected based on the vertical force profile and used as the reference values. Kinematic events were detected based on displacement, velocity or acceleration signals of the dorsal hoof marker depending on the algorithm using (i) defined thresholds associated with derived movement signals and (ii) specific events in the derived movement signals. Method comparison was performed by calculating limits of agreement, accuracy, between-horse precision and within-horse precision based on differences between kinetic and kinematic event. In addition, we examined the effect of force thresholds ranging from 50 to 150 N on the timings of kinetic events. The two approaches resulted in very good and comparable performance: of the 3,074 processed footfall events, 95% of individual foot on and foot off events differed by no more than 26 ms from the kinetic event, with average accuracy between −11 and 10 ms and average within- and between horse precision ≤8 ms. While the event-based method may be less likely to suffer from scaling effects, on soft ground the threshold-based method may prove more valuable. While we found that use of velocity thresholds for foot on detection results in biased event estimates for the foot on the inside of the circle at trot, adjusting thresholds for this condition negated the effect. For the final four algorithms, we found no noteworthy bias between conditions or between front- and hind-foot timings. Different force thresholds in the range of 50 to 150 N had the greatest systematic effect on foot-off estimates in the hind limbs (up to on average 16 ms per condition), being greater than the effect on foot-on estimates or foot-off estimates in the forelimbs (up to on average ±7 ms per condition).

Foot placement of the equine forelimb: Relationship between foot conformation, foot placement and movement asymmetry

REASONS FOR PERFORMING STUDY

Hoof conformation, foot placement and movement asymmetry are routinely assessed as part of the lameness examination. However, to date, few studies have described these parameters, or the interplay between them, in the general horse population.

OBJECTIVES

To assess foot conformation and foot placement in the forelimbs of a group of general purpose horses and investigate the relationships between foot placement, foot conformation and movement asymmetry.

STUDY DESIGN

Observational cross-sectional study.

METHODS

Forty-three horses were included in the study. Measurements were taken from photographs of each forelimb to assess foot conformation. Video footage was recorded simultaneously from perpendicular cameras at both walk and trot and used to categorise foot placement. Inertial sensor data were used to assess head movement asymmetry in trot.

RESULTS

There was a high degree of variation in foot placement between and within horses, but a 'lateral heel' placement was most common in walk and a 'lateral' placement most common in trot. Foot placement was associated with dorsal and palmar hoof angles but there was no relationship between foot placement and the other conformation parameters, nor with movement asymmetry. Moderate negative correlations were found between several of the conformation parameters and movement asymmetry.

CONCLUSIONS

A relationship exists between foot conformation and movement asymmetry with decreasing hoof width and hoof length related to increasing amount of movement asymmetry. In the population of horses studied here--deemed to be 'well functioning' by their owners/riders--foot placement was found to be independent of movement asymmetry and, to a large extent, independent of foot conformation.

Biometria podal de equídeos (Equus sp Linnaeus, 1758) de tração

Os equídeos têm sido largamente utilizados como meio de tração desde épocas remotas, sem que se atente às intempéries às quais as cápsulas ungueais são submetidas, principalmente pelo atrito, pelo impacto e pelas forças atuantes no momento da tração. Para a mensuração das cápsulas ungueais foi utilizado paquímetro de aproximação milimetral e, para determinar a angulação da face parietal com o solo, transferidor de 180º. Os parâmetros das cápsulas ungueais mensurados foram: o comprimento, a largura, a altura da superfície dorsal da face parietal, a largura dos tórus córneos, a altura dos tórus córneos mediais e laterais, o comprimento e a largura da cunha córnea. Para confecção do presente trabalho foram utilizados 181 animais empregados em atividade de tração no Município de Petrolina (PE), sendo 56 equinos, 97 asininos e 28 muares, dentre machos e fêmeas, com diferentes massas corporais e diferentes idades. Os resultados foram tabulados e poderão servir de subsídio para determinação do padrão anatômico destes animais na referida região. Foi possível verificar as práticas às quais os animais são submetidos, como casqueamento, ferrageamento e excesso de carga, o que pode acarretar má distribuição da carga nos membros e na própria cápsula ungueal, gerando patologias do aparelho locomotor. Frequentemente, observava-se o desequilíbrio médio-lateral das úngulas, uma vez que o tórus córneo medial era maior que o lateral, desencadeando alterações no aprumo e prejudicando as posições ortostática e ortodinâmica, as quais poderiam ser resolvidos com práticas de casqueamento e ferrageamento, reduzindo as afecções do aparelho locomotor.

Pressure plate analysis of toe-heel and medio-lateral hoof balance at the walk and trot in sound sport horses

Empirically, equine distal limb lameness is often linked to hoof imbalance. To objectively quantify dynamic toe-heel and medio-lateral hoof balance of the vertical ground reaction force in sound sport horses, seven Royal Dutch Sport Horses were led at the walk and trot over a dynamically calibrated pressure plate. Forelimb hoof prints were divided into a toe and heel region and a medial and lateral zone. Toe-heel and medio-lateral hoof balance of the vertical ground reaction force were calculated throughout the stance. Toe-heel balance was highly symmetrical between contralateral limbs at both gaits. At the walk, medio-lateral balance of both forelimbs presented higher loading in the lateral part of the hoof throughout the stance. However, at the trot, left medio-lateral balance presented higher loading of the medial part of the hoof at impact, whereas the right limb showed higher loading of the lateral part of the hoof in all horses, and both limbs presented increased lateral loading at the end of the stance. This study provides objective data for toe-heel and medio-lateral hoof balance in sound sport horses.

Farriery for the hoof with low or underrun heels

Underrun heels are common and involve hoof capsule distortion in which the horn tubules of the heels undergo bending and lengthening, resulting in decreased strength and functionality. The syndrome varies in clinical presentation, depending on duration, severity of distortion, presence of secondary problems, and presence of lameness. Primary treatment goals are to maintain soundness and functional integrity of the foot and to establish a normal hoof capsule. Resolution of the problem is generally not achieved in horses in a heavy work schedule, and realistic goals in this situation are to maintain function, alleviate lameness, and arrest progression of the distortion.

Forces applied with a hoof tester to cadaver feet vary widely between users

Hoof testers are commonly used in equine practice. In this study, we determined the intraoperator and interoperator reliability of force application with hoof testers for different groups: experienced veterinarians, novices and farriers. For this purpose, we have developed and validated an instrumented hoof tester. Forces varied significantly between the different regions of the foot for experienced operators applying the highest forces to the heels, then the frog, then the toe, and the lowest forces to the quarters. Novices applied significantly more force to the toe versus the frog. Intraoperator reliability varied significantly between regions and operators. Novices had the narrowest width of limits of agreement for the frog and heel, but the widest for the toe and the quarters, whereas farriers had the narrowest width of agreement for the toe and quarter. Force application differed significantly between groups for the frog and heel regions, but not the toe and quarters. Veterinarians applied higher forces to the frog compared with farriers and novices, and higher forces to the heel compared with novices. This study showed that hoof tester forces vary widely within and between operators, and standardisation of hoof tester use is needed to make this diagnostic test more reliable.

Relationship of foot conformation and force applied to the navicular bone of sound horses at the trot

REASONS FOR PERFORMING STUDY

Collapsed heels conformation has been implicated as causing radical biomechanical alterations, predisposing horses to navicular disease. However, the correlation between hoof conformation and the forces exerted on the navicular bone has not been documented.

HYPOTHESIS

The angle of the distal phalanx in relation to the ground is correlated to the degree of heel collapse and foot conformation is correlated to the compressive force exerted by the deep digital flexor tendon on the navicular bone.

METHODS

Thirty-one shod Irish Draught-cross type horses in routine work and farriery care were trotted over a forceplate, with 3-dimensional (3D) motion analysis system. A lateromedial radiograph of the right fore foot was obtained for each horse, and various measurements taken. Correlation coefficients were determined between hoof conformation measurements and between each of these and the force parameters at the beginning (15%) of stance phase, the middle of stance (50%) and at the beginning of breakover (86% of stance phase). Significance was defined as P<0.05.

RESULTS

The force exerted on the navicular bone was negatively correlated (P<0.05) to the angle of the distal phalanx to the ground and to the ratio between heel and toe height. This was attributed to a smaller extending moment at the distal interphalangeal joint. There was not a significant correlation between the angle of the distal phalanx and the degree of heel collapse, and heel collapse was not significantly correlated to any of the force parameters.

CONCLUSIONS

Hoof conformation has a marked correlation to the forces applied to the equine foot. Heel collapse, as defined by the change in heel angle in relation to toe angle, appears to be an inaccurate parameter. The forces applied on the foot are well correlated to the changes in the ratio of heel to toe heights and the angles of the distal phalanx.

POTENTIAL RELEVANCE

Assessment of hoof conformation should be judged based on these parameters, as they may have clinical significance, whereas parallelism of the heel and toe is of less importance.

Comparison of the trimming procedure of six different farriers by quantitative evaluation of hoof radiographs

Hoof preparation and shoe fit are integral to the long term soundness and athletic ability of horses. The farrier influences the balance of the hoof by both the trimming and the shoeing procedure. The goal of this study was to investigate and quantify the influence of the farrier on hoof parameters by trimming. Forty Warmblood horses ranging in age from 6-12 years and withers height 162-172cm were included. They were divided into six groups consisting of six or seven horses each, shod by one of six different farriers. The hoofs of the horses were radiographed twice using a standardised method before and after trimming. Measurements were taken from digitalised radiographs using a software program. Significant differences were identified between farriers for almost all parameters on the lateromedial radiographic views after two consecutive trimming procedures. Comparing the results of both trimming procedures, significant differences for several farriers were found in the lateromedial and dorsopalmar views. There were significant differences for most of the measured hoof parameters between the six farriers and between consecutive trimmings of the same farrier. The results underline the individual influence of the farrier on hoof shape and balance.

Evaluation of changes in architecture of the stratum internum of the hoof wall from fetal, newborn, and yearling horses

OBJECTIVE

To evaluate morphologic changes of the stratum internum of hooves from near-term fetal, newborn, and yearling horses.

ANIMALS

Feet from 27 near-term equine fetuses, 19 newborn foals, and 8 yearlings.

PROCEDURES

Primary epidermal laminae (PEL) of the stratum internum were examined for evidence of architectural changes.

RESULTS

In near-term fetuses, the PEL had a homogeneous appearance and symmetric distribution around the hoof wall with no significant differences in PEL density between the toe and quarters. However after birth, branched laminae at the toe formed within the first few weeks, which significantly increased PEL density at the toe, compared with the quarters. In yearlings, morphology of the PEL differed from that in younger foals and the PEL density was significantly greater at the toe than the quarters. The PEL density at the toe and medial and lateral quarters was significantly different from each other, as these PEL densities appeared to have been associated with conformation. No significant differences in PEL densities between forefeet and hind feet were detected in any group.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings indicate that the stratum internum of the inner hoof wall undergoes several morphologic changes shortly after birth. The PEL become branched with a greater PEL density at the toe than the quarters. In an asymmetric foot, more PEL were associated with the sloping side than the steep side of the foot. Findings suggested that PEL growth may also occur by bifurcation as well as by mitosis from the coronet and that wall stress may be associated with increased PEL density.

Dynamic pressure measurements for the detailed study of hoof balance: the effect of trimming

REASONS FOR PERFORMING STUDY

Studies on hoof balance have, so far, only assessed the effects of strong and relatively unrealistic interventions due to technical limitations of measuring equipment. For the assessment of more subtle interventions, other techniques are necessary.

OBJECTIVES

To test a sensitive pressure measurement system during locomotion and to set a standard for further studies by using the system to evaluate the effects of trimming.

METHODS

Eighteen horses were measured before and after trimming with an interval of 4 weeks. Trimming was standardised to a straight hoof-pastern axis. The horses trotted over a pressure/force measuring system, with a temporal resolution of 240 Hz and a spatial resolution of 0.39 cm2.

RESULTS

The preferred way of landing was lateral, asymmetrical in both front and hind feet. The duration of landing was shorter in forelimbs than in hindlimbs with an equal decreasing trimming effect. Horses had a fixed hoof-unrollment pattern; the centre of pressure (CoP) travelled towards a maximum lateral deviation and returned towards the dorsopalmar/plantar axis of the hoof. Trimming decreased the intra-individual left/right difference in maximum lateral displacement.

CONCLUSIONS

The technique used provided easily accurate data to quantify hoof balance characteristics and to measure short-term trimming effects.

POTENTIAL RELEVANCE

Determination of CoP patterns has added value in gait analysis and can improve our understanding of the effects of different interventions on hoof balance.

Relationship between velocity and temporal variables of the flat shod running walk

The running walk of the Tennessee Walking Horse is often described as a faster variation of the walk, indicating the importance of velocity on the mechanics of the gait. Variations in gait variables create difficulties in clearly identifying the normal and abnormal running walk in a clinical evaluation. The objectives of this study were, therefore, to describe the flat shod running walk and to determine the relationship between velocity and the running walk. From frame-by-frame analysis of 60 Hz film, temporal variables were averaged for 6 strides from 6 horses performing an 'easy' (slow) and 'strong' (fast) running walk during a flat shod, easy-rider Tennessee Walking Horse show class. The running walk at both velocities was a 4-beat, symmetrical stepping gait with a lateral footfall sequence and lateral couplets. The velocity ranged from mean +/- s.d. 2.66 +/- 0.34 to 3.80 +/- 0.18 m/s. For both velocities (slow, fast), hind stance as a percentage of stride duration (58 +/- 3%, 56 +/- 2%) was significantly longer than fore (51 +/- 5%, 48 +/- 1%); diagonal advanced placement (29 +/- 2%, 37 +/- 4%) and lift-off (35 +/- 5%, 39 +/- 2%) were significantly longer than lateral (advanced placement: 22 +/- 2%, 12 +/- 3%; lift-off: 18 +/- 4%, 10 +/- 2); and lateral bipedal support (50 +/- 9%, 67 +/- 7%) was significantly longer than diagonal (27 +/- 6%, 16 +/- 4%). Strong correlations were found between velocity and diagonal advanced placement (0.640), lateral lift-off (-0.924) and diagonal (-0.648) and lateral (0.904) bipedal support. Understanding the running walk and the gait variations due to velocity may be important to both the performance and soundness of the Tennessee Walking Horse.

In-shoe foot force sensor to assess hoof balance determined by radiographic method in ponies trotting on a treadmill

Adaptation of an in-foot shoe force sensor and the gait analysis system 'Fscan' makes it possible to monitor the distribution of the vertical forces under the equine foot in motion. The aim of this study is to investigate the effects of two different trimmings on forces under the foot during the trot. The first one increased the height of the lateral hoof wall and the second one restored the mediolateral balance of the foot. These two trimmings were examined by using a radiographical method that quantifies the interphalangeal articular asymmetries due to asymmetrical bearing. The location of the centre of force of the weight-bearing foot and the distribution of the forces applied to the lateral and medial solar surfaces during a stride were analyzed. After optimal trimming, the centre of force of the weight-bearing foot tended to approach the centre of the palmar figure, perpendicular to the distal interphalangeal joint centre. The sum of the forces recorded under the lateral and medial parts respectively of the foot during one stride tended to balance out after corrective trimming.

Tubule density of the stratum medium of horse hoof

The number of tubules/mm2 (tubule density) of horse hoof horn was quantified in samples taken from the left forefeet of 8 randomly selected slaughterhouse horses in order to establish the normal tubule density characteristics at the midline dead centre (MDC) for the stratum medium of horse hoof. In the past the measurement of tubule distribution within the hoof has lacked objectivity. The horse hoof tubule density results are compared to a recent objective study carried out on pony hoof. A similar 4 zone pattern of tubule density was observed, although the precise zonal boundaries and tubule density values differed to those found for pony hoof. There were significant differences in tubule density between zones. Comparison with pony hoof revealed significant tubule density differences in zones 1, 2 and 4; however, there was no significant difference in zone 3. The existence of a 4 zoned pattern of tubule density for horse hoof, as for pony hoof, has been confirmed.