Long Toes in the Hind Feet and Pain in the Gluteal Region: An Observational Study of 77 Horses

This study deals with the relationship between long toes in the hind feet and pain in the gluteal region in horses, and the remedial value of trimming/shoeing that moves the breakover point back at the toe. Seventy seven client-owned horses were studied, 67 shod riding horses retrospectively and 10 barefoot broodmares prospectively. The 10 mares were evaluated twice, and 24 of the 67 riding horses were re-evaluated at the next shoeing, for a total of 111 observations. Each horse underwent gluteal palpation and lateral radiographs of both hind feet. Toe length was quantified as breakover distance (BD), the horizontal distance between the tip of the third phalanx and the dorsalmost point at which the wall/shoe was in contact with the ground. The BD was then shortened with trimming +/− shoeing to a length of ≤15mm (shod horses) or ≤20 mm (barefoot horses). The 24 riding horses were re-evaluated 4-6 weeks later and the 10 broodmares 1 week after trimming.     

Equine Behavior Problems—Around Farriery: Foot Pain in 11 Horses

Although foot pain may clearly be the cause when a horse with foot pathology does not tolerate farriery, it may be overlooked or underappreciated as the cause of this behavioral problem when the pathology is mild and/or chronic. In this study, the records of 11 adult horses whose behavior for farriery initially warranted sedation for trimming and shoeing were reviewed. All 11 horses had a history of chronic lameness that was mild to moderate, but foot pain was the presenting complaint in only seven horses - all with chronic laminitis. The other four horses had abnormal foot conformation (long-toe, low-heel, or “club foot), but the lameness had not been attributed to the foot. All 11 horses showed improvement in gait with corrective trimming and shoeing. In each case, sedation for farriery could be discontinued after one to six visits, concurrent with the improvements in gait and foot pathology. On the basis of the survey results from 17 professional farriers, an ethogram of farriery-related undesirable horse behavior was developed.     

Hoof growth between two shoeing sessions leads to a substantial increase of the moment about the distal, but not the proximal, interphalangeal joint

REASONS FOR PERFORMING STUDY: There is little insight into the effects of routine farriery on the internal structures of the distal limb in sound horses. OBJECTIVES: To measure the effect of change in hoof conformation during a shoeing interval on the moments about the proximal and distal interphalangeal joints (PIPJ, DIPJ) and to determine whether and how the horse compensates for this change in hoof conformation. METHODS: Both front feet of 9 sound Warmblood horses were measured while standing on a pressure-force measuring system and radiographed in a lateromedial direction shortly after shoeing and 8 weeks later. From these data, ground reaction forces (GRF) and lever arms were measured in order to calculate joint moments. RESULTS: After 8 weeks, the moment about the PIPJ did not increase significantly, but the moment about the DIPJ did so, indicating a compensatory mechanism for a change in hoof conformation in the DIPJ. CONCLUSIONS: Standing horses compensate for hoof conformation change during an 8-week shoeing interval, which leads to increased DIPJ extension and consequently an increased loading of the deep digital flexor tendon. POTENTIAL RELEVANCE: This study quantifies the effect of a shoeing interval on the internal structures of the foot and helps to determine an appropriate shoeing interval for individual horses in which the hoof with the lowest hoof angle is the best indicator. The exact determination of an optimal individual shoeing interval requires further study.     

The effect of hoof trimming on radiographic measurements of the front feet of normal Warmblood horses

The understanding of the normal position of the third phalanx (P3) and the distal sesamoid bone in relation to the size and shape of the hoof capsule in sound horses is helpful in the diagnosis of equine foot lameness. Some measurements on radiographs used to define the position of the pedal bone within the hoof capsule are significantly influenced by hoof trimming and the height of the withers. In this study, the front hooves of 40 Warmblood horses were radiographed twice, eight weeks apart, both before and after their hooves were trimmed by an experienced farrier. Using the software programme Metron PX, 22 parameters on the lateromedial view and 16 parameters on the dorsopalmar view were measured and the effect of hoof trimming and height of the withers were calculated, respectively. Some of the hoof parameters showed mild positive correlation with the height of the withers. In 70% of the horses the left hoof capsule and P3 were significantly larger than the right. Hoof trimming had a remarkable influence on hoof conformation, especially for parameters in the toe region. Of all the measurements that describe the position of the third phalanx (P3) in relation to the hoof capsule, the distances between the distal tip of P3 to the solar surface of the foot, P3 to the tip of the toe and P3 to the point of break-over showed the greatest differences before and after trimming. The database of the present study can be used by farriers and veterinarians as a guideline for routine and corrective shoeing of Warmblood horses.     

Effect of foot balance on the intra-articular pressure in the distal interphalangeal joint in vitro

REASONS FOR PERFORMING STUDY: Increased joint pressure has been implicated in the progression of osteoarthritis. HYPOTHESIS: That intra-articular pressure in the distal interphalangeal joint (DIP) is significantly higher in legs loaded with heel up (HU), low heel (TU), lateral side up (LU) and medial side up (MU) imbalance compared to the balanced position. METHODS: Twelve elbow down limbs were compressed in a hydraulic loading jig and DIP pressure measured. RESULTS: Elevating the heels by 5 degrees significantly increased DIP pressure. After 5 ml of contrast was injected into the joint, heel elevation caused a greater increase in DIP pressure and heel lowering decreased DIP pressure. Silicone rubber castings were taken of 20 DIP whilst under load. The articular contact area was localised on the dorsal aspect in the HU position, palmar aspect in the TU position and towards the elevated side with lateromedial imbalance. CONCLUSIONS: Altered foot orientation, which could result from trimming and shoeing, therefore influences intra-articular pressure in the DIP and the articular contact area. POTENTIAL CLINICAL RELEVANCE: The results support the view that a balanced foot is the ideal and that the elevated heels may be detrimental to long term viability of the DIP joint.     

Use of a pressure plate to analyse the toe-heel load redistribution underneath a normal shoe and a shoe with a wide toe in sound warmblood horses at the walk and trot

The objective of this study was to use a pressure plate to quantify the toe-heel load redistribution in the forelimbs of sound warmblood horses with normal shoes and shoes with a wide toe and narrow branches, used empirically in the treatment of superficial digital flexor tendon or suspensory ligament injuries. In a crossover-design study, six horses, randomly shod with normal shoes and shoes with a wide toe, were led over a dynamically calibrated pressure plate to record data from both forelimbs. There were no significant differences between both shoes in the toe-heel index of stance time, peak vertical force and vertical impulse. For the adapted shoe, the peak vertical pressure was slightly lower and was exerted slightly earlier in the stance phase, albeit not significantly. However, the significantly larger toe contact area of the adapted shoe resulted in a significantly lower total vertical pressure in the toe region. Hence, the pressure plate adequately visualised the individual loading of the toe and heel region, and clearly demonstrated the altered pressure distribution underneath the shoe with a wide toe. Although further research on a deformable surface is needed to confirm this hypothesis, the pressure redistribution from the toe to the heels could promote sinking of the heels in arena footing, thereby mimicking the biomechanical effects of a toe wedge and providing a rationale for its application in the treatment of SDFT or SL injuries. The pressure measuring equipment used in this study can offer to the clinician a diagnostic tool for the evaluation of the load distribution underneath the equine hoof and for the fine-tuning of corrective shoeing.     

The foot–surface interaction and its impact on musculoskeletal adaptation and injury risk in the horse

The equine limb has evolved for efficient locomotion and high‐speed performance, with adaptations of bone, tendon and muscle. However, the system lacks the ability seen in some species to dynamically adapt to different circumstances. The mechanical interaction of the limb and the ground is influenced by internal and external factors including fore–hind mass distribution, lead limb, moving on a curve, shoeing and surface properties. It is unclear which of the components of limb loading have the largest effect on injury and performance but peak load, impact and vibration all play a role. Factors related to the foot–ground interface that limit performance are poorly understood. Peak performance varies vastly between disciplines but at high speeds such as racing and polo, force and grip are key limits to performance.     

Shoeing sound warmblood horses with a rolled toe optimises hoof-unrollment and lowers peak loading during breakover

REASONS FOR PERFORMING STUDY: Overload injuries in sport horses commonly occur; shoeing techniques are believed to be important in prevention of these injuries, but there is a paucity of scientific information identifying the potential connection. OBJECTIVES: To test a horseshoe with a modified rolled toe designed to ease the process of breakover and decrease loading of lesion-prone structures of the distal limb. METHODS: Twenty clinically sound Warmblood horses trotted over a track containing a pressure/force measuring system and 6 infrared cameras. The horses were measured with 2 types of shoes, standard flat shoes and shoes with a rolled toe. The shoeing procedure was randomised and horses had 2 days between measurements to adapt to the shoes. RESULTS: Limb placement and timing characteristics, e.g. breakover duration, did not change significantly. There was an improvement in the ease of movement to roll over the toe in the shoes with a rolled toe, due mainly to a smoother hoof-unrollment pattern. The peak indicative moment decreased substantially at the onset of breakover in the shoe with the rolled toe. CONCLUSIONS: With a rolled toe the process of hoof-unrollment is smoother, which improves the coordination of this process, and lowers peak loading of the distal limb during breakover. POTENTIAL RELEVANCE: This study stresses the importance of proper shoeing in sound horses, showing that shoe modifications can optimise the loading characteristics of the distal limb and therefore might be a means to prevent sport horses from overload injuries.     

The ossification of cartilages of the distal phalanx in the horse: An anatomical, experimental, radiographic and clinical study

This paper describes some anatomical findings relatedto ossification of the distal phalanx cartilages by anatomical and computerized tomographic sections. Radiographic findings of ossification were analyzed and correlated to age and breed. Ossification was found in 10% of warmblood horses and in 80% of draft horses and was much more severe in draft horses than in warmblood horses. The expansion of the hoof was measured in the laboratory in several feet of warmblood and draft horses and was found to be minimal with no differences whether ossification was present or not. Computerized tomography was performed on a foot of a slaughtered horse before and after up to 7000N loading in the laboratory in order to study the eventual changes of the cartilages and the hoof. These structures seemed quite unaffected by the load and expansion of the horny capsule was minimal. Minor expansion seems an inevitable structural behavior of the hoof and the classical hoof mechanism is questioned. The clinical significance of ossification in its relation to lameness was individually determined during clinical examination and by comparison of groups of horses with and without ossification with groups of horses with lameness from the foot and proximal to the foot. The severity of the ossification was related to the onset of lameness and no correlation was found. It is concluded that the clinical significance of ossification is almost nil. Ossification is not painful when developing and not thereafter. There is no correlation between navicular disease and ossification of the cartilages either. Orthopedic shoeing is of no significance at all. An unfavorable advice in purchase examinations in sporting horses due to cartilage ossification is not justified in the author's opinion.     

Short-term effect of therapeutic shoeing on severity of lameness in horses with chronic laminitis

OBJECTIVE: To evaluate the short-term effects of 4 therapeutic shoeing systems on lameness and voluntary limb-load distribution in horses with chronic laminitis. ANIMALS: 10 horses with chronic laminitis. PROCEDURES: A clinical trial was conducted that used a concurrent control, crossover design to evaluate the relative effectiveness of a standard flat shoe, fullered egg-bar shoe, heart-bar shoe, and modified equine digital support system to alleviate chronic lameness in horses. Therapeutic success was assessed during a 7-day period by use of subjective (Obel grade and clinical score) and objective (force-plate data) evaluations. RESULTS: Comparison of pretreatment and intertreatment control data indicated that disease status of the horses did not change during the course of the study. None of the therapeutic shoeing treatments used resulted in a significant change in severity of lameness. CONCLUSIONS AND CLINICAL RELEVANCE: Results were interpreted to imply that substantial clinical improvement should not be expected during the first 7 days after therapeutic shoeing for the specific shoes tested in this study. On the basis of our results, we hypothesize that when used as the lone indicator of therapeutic success, severity of lameness may not be a valid indicator.     

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 162–172 cm 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.     

Photoelastic stress analysis of strain patterns in equine hooves after four-point trimming

OBJECTIVE: To evaluate changes in strain patterns in normal equine hooves following 4-point trimming, using photoelastic stress analysis. SAMPLE POPULATION: 15 equine front limbs with normal hoof configuration. PROCEDURE: Limbs were disarticulated at the carpometacarpal joint. Weight-bearing surfaces of each hoof were trimmed level to ensure 100% ground contact. Hoof walls were coated with a custom-made strain-sensitive plastic, and limbs were loaded to a third of body weight. Using a polariscope, strain distribution, magnitudes, and directions were evaluated in level hooves as well as before and after standardized 4-point trimming. Repeated-measures ANOVA was used to compare strain magnitudes and directions before and after trimming. RESULTS: In leveled specimens, strain fields were symmetrically distributed above the heels and at quarter-toe junctions along a line between the middle and distal thirds of the hoof wall. After 4-point trimming, strain epicenters localized above the contact points, whereas strain magnitudes significantly increased by approximately 50%. Decreasing contact area by 50% resulted in an additional significant increase (32%) in strain magnitude. Trimming did not have a significant effect on strain orientations. CONCLUSION AND CLINICAL RELEVANCE: This study documents that 4-point trimming results in strain concentration above the hoof contact points and that strain magnitude is dependent on contact area.     

Density and morphologic features of primary epidermal laminae in the feet of three-year-old racing Quarter Horses

OBJECTIVE: To quantify the density of primary epidermal laminae (PELs) around the solar circumference and evaluate the relationship between regional PEL density and hoof capsule morphology in horses. SAMPLE POPULATION: Forefeet from nine 3-year-old Quarter Horse cadavers. PROCEDURES: Data pertaining to gross features of hoof morphology and PEL variables, including number, density, and distribution patterns around the perimeter of the hoof wall and number of bar PELs, were collected. Tissues of the laminar junction were examined histologically. RESULTS: No significant differences were found between left and right forefeet with respect to gross hoof morphologic measurements. Mean +/- SD number of PELs, including those at the bars of the hoof, was 551 +/- 30. Primary epidermal laminar density in the toe was significantly higher, compared with that in the quarter and heel regions, and was higher on the lateral aspect of the foot, compared with the medial aspect. Feet were significantly wider on the lateral aspect of the foot, compared with the medial aspect, as measured across the widest point of the solar surface. Histologic examination revealed atypical laminar morphology at the toe. CONCLUSIONS AND CLINICAL RELEVANCE: Variations were detected in PEL density and morphology around the solar circumference of hooves from 3-year-old racing Quarter Horses. A better understanding of relationships between laminar density, laminar morphology, and gross morphology of the hoof capsule in different populations of horses may aid practitioners in diagnosis and treatment of disease involving the hoof wall in horses.     

The force and contact stress on the navicular bone during trot locomotion in sound horses and horses with navicular disease

Mechanical overload due to poor conformation or shoeing has been suggested to contribute to the development of navicular disease. While studies have determined the compressive force exerted on the navicular bone in normal horses, this has not been reported for horses with navicular disease. Also, the force has not been converted to stress by correction for contact area. In this study we developed a technique for the determination of the contact area between the deep digital flexor tendon and the navicular bone in vivo, and used a forceplate system to determine the force and stress on the bone at trot in 6 normal and eight diseased horses. The mean +/- s.d. peak force and peak stress were 5.62+/-1.45 N/kg and 2.74+/-0.76 MPa for the normal group and 6.97+/-1.50 N/kg and 3.07+/-0.55 MPa for the navicular disease group. The peak force and peak stress were similar for both groups but the force and stress in the horses with navicular disease were approximately double control group values early in the stance phase. This was due to a higher force in the deep digital flexor tendon, which was attributed to a contraction of the deep digital flexor muscle in early stance in an attempt to unload the heels.     

Evaluation of the hoof and foot relevant to purchase.

The equine hoof and foot are the most commonly affected anatomic sites of lameness encountered during purchase examination of the performance horse. This article presents a thorough, systematic approach to the clinical evaluation of the hoof and foot relevant to the pre-purchase examination. Normal and abnormal conditions are discussed with reference to their potential effects on future performance and soundness. Proper trimming, balancing, and shoeing principles are emphasized.     

Hoof Size and Symmetry in Young Catalan Pyrenean Horses Reared Under Semi-Extensive Conditions

Hoof balance and conformation have been researched extensively in performance horses. The aim of this study was to describe the solar length, width, area, and symmetry of fore and hind hooves of young Catalan Pyrenean horses (Cavall Pirinenc Català) reared under semi-extensive conditions and lacking any hoof care, trimming, or shoeing. Measurements were performed on the isolated limbs. Solar length, width, and surface area of 128 distal limbs obtained from 32 yearlings demonstrated no significant differences between left and right forelimbs or hind limbs for any variable (P = .413, .975, and .486, respectively). There were no significant differences between fore and hind limbs for length (P = .831), whereas the forehoof width and area were significantly larger than those of the hind limb (P < .001). Interindividual variability was low for hoof width and length (coefficient of variation, <10%) and slightly larger for solar area (coefficient of variation, <15%). All variables had very high left-right symmetry (≥98%). No relevant laterality could be identified (directional asymmetry indices <2%). Notwithstanding the absence of regular hoof care, young Catalan Pyrenean horses reared under semi-extensive conditions present homogenous hoof sizes and a high level of symmetry for hoof length, width, and solar area.     

Voluntary limb-load distribution in horses with acute and chronic laminitis

OBJECTIVES: To compare limb-load distribution between horses with and without acute or chronic laminitis. ANIMALS: 10 horses with carbohydrate-induced acute laminitis, 20 horses with naturally occurring chronic laminitis, and 20 horses without foot abnormalities (controls). PROCEDURES: Limb-load distribution was determined, using a custom-designed system that allowed simultaneous quantification of the mean percentage of body weight voluntarily placed on each limb (ie, mean limb load) and the SD of the mean load over a 5-minute period (ie, load distribution profile [LDP]). Load distribution profile was used as an index of frequency of load redistribution. RESULTS: Mean loads on fore- and hind limbs in control horses were 58 and 42%, respectively, and loads were equally and normally distributed between left and right limbs. In addition, forelimb LDP was greater, compared with hind limbs, and was affected by head and neck movement. In comparison, limb-load distribution in horses with chronic laminitis was characterized by an increase in the preferential loading of a forelimb, a decrease in total forelimb load, and an increase in LDP that was correlated with severity of lameness. In horses with carbohydrate-induced acute laminitis, mean limb loads after onset of lameness were not different from those prior to lameness; however, LDP was significantly decreased after onset of lameness. CONCLUSION AND CLINICAL RELEVANCE: Quantification of limb-load distribution may be an applicable screening method for detecting acute laminitis, grading severity of lameness, and monitoring rehabilitation of horses with chronic laminitis.     

Changes in location of centre of pressure and hoof-unrollment pattern in relation to an 8-week shoeing interval in the horse

REASONS FOR PERFORNING STUDY: In order to optimise shoeing and shoeing conditions, it is essential to know how the horse adapts to a common shoeing interval. OBJECTIVES: To measure changes in location of the centre of pressure (CoP) and hoof-unrollment pattern during a shoeing interval and to assess whether these changes in CoP result directly from changes in hoof conformation or are also influenced by compensatory mechanisms. METHODS: Eighteen horses were trotted over a pressure-force measurement system shortly after shoeing and 8 weeks later. The position of the CoP was measured and also predicted using calculations based on changes in hoof conformation. RESULTS: The measured shift in CoP was less than calculated. This difference was largest in the hind feet. The hoof-unrollment pattern stayed basically the same in the front feet, but in the hind feet there was a substantial lateral shift of the trajectory of the CoP. CONCLUSIONS: Horses can compensate, to a certain extent, for changes in hoof conformation that develop during 8 weeks on shoes. As the capacity to compensate is less in the forelimbs, the relative increase in loading of these limbs during a shoeing interval is larger than in the hindlimbs. Potential relevance: This study provides essential basic data for the development of science-based shoeing techniques.     

ULTRASONOGRAPHY OF THE SOLAR ASPECT OF THE DISTAL PHALANX IN THE HORSE

Ultrasonographic examinations were performed on the solar aspect of the distal phalanx of 10 feet of five normal live horses (Group 1), 22 feet of seven normal cadavers (Group 2), and nine feet of five horses with pathology of the dorsal solar aspect of the distal phalanx (Group 3). Lateromedial radiographs of the distal phalanx were made in all groups, and in Group 2, digits were sagitally sectioned after imaging. The ultrasonographic and radiographic appearance of the sagittal solar aspect of the distal phalanx was described. Measurements of the distance between the sole and the distal tip of the distal phalanx (A), the solar aspect of the apex of the frog and the distal phalanx (B), and the body of the frog's surface and flexor surface of the distal sesamoid bone (C) were made ultrasonographically, radiographically, and on the sectioned cadaver specimens. There was no statistical difference between the radiographic, ultrasonographic, and direct cadaver measurements in A and C. In B, there was a statistical difference between the radiographic, ultrasonographic, and cadaver measurements-most likely as a result of the difference in trimming of the frog apex. Ultrasonographic and radiographic examination of the nine feet of the five horses in Group 3 were performed and the abnormalities described. Color flow and power Doppler ultrasonography were performed on the normal sagittal solar distal phalanx, on the impar distal sesamoidean ligament, and at the insertion of the deep digital flexor tendon on the facies flexoria of the distal phalanx. Power Doppler in these horses showed blood flow at 0.16-0.48 kHz at the tip of the distal phalanx and at 0.16 kHz at the deep digital flexor tendon insertion and in the impar distal sesamoidean ligament. Using color flow Doppler in normal horses mean blood flows ranged from 1.8 to 5.4 cm/s at the tip of the distal phalanx and 1.8-2.0 cm/s at the deep digital flexor tendon insertion and in the impar distal sesamoidean ligament.     

A Cross-Sectional Survey of Forelimb Hoof Conformation and the Prevalence of Flat Feet in a Cohort of Thoroughbred Racehorses in New Zealand

Racehorses in New Zealand predominantly train counter clockwise. This training pattern has been associated with between forelimb differences in bone mineral density profile and asymmetrical limb loading after training. At present, there is limited data on the hoof conformation of these racehorses. Distal forelimb and digital hoof conformation data were collected from 75 Thoroughbred racehorses (2–5 years old) from two training yards. Digital conformation was subjectively graded, and multiple hoof measurements were made with a modified tire gauge (sole and sulci depth) and from digital photographs. All the horses were shod by two registered master farriers within a median of 15 (interquartile range [IQR], 1–25) days before measurement. There were few distal limb conformation abnormalities scored. Most (62/75) horses presented with some deviation from normal hoof parameters, with 2 (IQR, 1–3) abnormalities reported per horse. The most common hoof abnormality was uneven sulci, which was identified in 43 horses and 59 affected hooves, followed by higher medial hoof wall height in 38 horses and 53 affected hooves. Many of the linear and hoof angle measurements and their ratios were within the bounds reported within the literature and indicative of a balanced foot. The length and width measurements increased with horse age. The dorsal hoof wall (DHW) length:heel length ratios were consistently less than 3:1, and the absolute difference between toe and heel angle was generally greater than 5°. Between limb hoof variation was identified for a number of the morphologic measurements including frog length and sole length and the ratio of sole width:sole length. Flat feet (lack of concave solar surface) were identified in 21/75 (28%) horses and in 28/150 (19%) forelimb hoofs. More horses had a flat left foot (10/75) than right foot (4/75), but seven horses had both feet classified as being flat. Flat feet had 2.4 (1.1–5.6, P = .036) greater odds of presenting with uneven sulci. These data indicate that uneven sulci depth and flatter hooves with may be a typical presentation of Thoroughbred feet. Asymmetry in measurements between limb may reflect the greater loading of the left forelimb when race training counter clockwise.