The lipopolysaccharide model for the experimental induction of transient lameness and synovitis in Standardbred horses.

An established lipopolysaccharide (LPS) model previously described in Warmbloods, was inconsistent in Standardbred horses, where lameness was not detected despite the presence of synovitis. The present study aimed to determine the dose of LPS from E. coli O55:B5 required to induce mild to moderate lameness following middle carpal joint injection in Standardbred horses and to quantitate the induced lameness over time, with and without anti-inflammatory pre-treatment. In a baseline trial, eight healthy, clinically sound Standardbred horses were used in a rule-based dose-escalation design trial, starting at a dose of 10 endotoxin units (EU). Lameness at trot was evaluated visually and quantitatively (using an inertial-sensor system and pressure plate analysis). Synovial fluid aspirates were analysed for total nucleated cell counts, total protein and prostaglandin E2 (PGE2). Following 2 months wash-out, the effective LPS-dose determined in the baseline trial was used to evaluate the effect of anti-inflammatory treatment. A mixed model for repeated measures with horse as random effect was used for analysis. After injection of 10 EU LPS, the desired degree of lameness was observed in the baseline trial, with maximal lameness at post-injection hour (PIH) 4, followed by a rapid decline and return to baseline by PIH 48. No lameness was observed following pre-treatment with meloxicam. In synovial fluid, PGE2 was significantly higher at PIH 8 and PIH 24 in the baseline trial compared with following meloxicam pre-treatment. In conclusion, injection of the middle carpal joint with 10 EU LPS consistently induces a transient lameness and synovitis in Standardbred horses.

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 use of equine chondrogenic-induced mesenchymal stem cells as a treatment for osteoarthritis: A randomised, double-blinded, placebo-controlled proof-of-concept study.

BACKGROUND: There is a need to improve therapies for osteoarthritis in horses. OBJECTIVES: To assess the efficacy of equine allogeneic chondrogenic-induced mesenchymal stem cells combined with equine allogeneic plasma as a novel therapy for osteoarthritis in horses. STUDY DESIGN: Randomised, double-blinded, placebo-controlled experiment. METHODS: In 12 healthy horses, osteoarthritis was induced in the metacarpophalangeal joint using an osteochondral fragment-groove model. Five weeks after surgery, horses were randomly assigned to either an intra-articular injection with chondrogenic-induced mesenchymal stem cells + equine allogeneic plasma (= intervention) or with 0.9% saline solution (= control). From surgery until the study end, horses underwent a weekly joint and lameness assessment. Synovial fluid was collected for cytology and biomarker analysis before surgery and at Weeks 5, 5 + 1d, 7, 9 and 11. At Week 11, horses were subjected to euthanasia, and the metacarpophalangeal joints were evaluated macroscopically and histologically. RESULTS: No serious adverse events or suspected adverse drug reactions occurred during the study. A significant improvement in visual and objective lameness was seen with the intervention compared with the control. Synovial fluid displayed a significantly higher viscosity and a significantly lower glycosaminoglycan concentration in the intervention group. Other biomarkers or cytology parameters were not significantly different between the treatment groups. Significantly less wear lines and synovial hyperaemia were present in the intervention group. The amount of cartilage oligomeric matrix protein, collagen type II and glycosaminoglycans were significantly higher in the articular cartilage of the intervention group. MAIN LIMITATIONS: This study assessed the short-term effect of the intervention on a limited number of horses, using an osteoarthritis model. This study also included multiple statistical tests, increasing the risk of type 1 error. CONCLUSIONS: Equine allogeneic chondrogenic-induced mesenchymal stem cells combined with equine allogeneic plasma may be a promising treatment for osteoarthritis in horses. The Summary is available in Spanish - see Supporting Information.

Can the hoof be shod without limiting the heel movement? A comparative study between barefoot, shoeing with conventional shoes and a split-toe shoe.

Conventional shoeing restricts heel movement, which may have a negative effect on the orthopaedic health of the horse. A randomised crossover experimental study using noninvasive techniques was performed to compare the mediolateral heel movement in barefoot horses, horses shod with a conventional toe clipped shoe and with a new type of shoe with a split toe. In eight horses, 16 forelimbs were tested barefoot, shod with a conventional shoe and with the split-toe (ST) shoe, in random order. A displacement sensor was secured on the heels and measurements were collected continuously at a frequency of 679Hz while horses were exercised on a treadmill at the walk (1.8m/s), trot (3.5m/s) and canter (8m/s). Differences in heel movement between the conditions were analysed using a generalised estimating equations approach. The conventional shoe was associated with significantly less heel expansion compared with the ST shoe and barefoot situation in all gaits (P≤0.001). Heel expansion with the ST shoe was not significantly different from the barefoot condition. For all gaits, shoeing was associated with a significant reduction in heel contraction compared with the barefoot situation (P≤0.038), except for the heel contraction at the canter using a conventional shoe. In conclusion, the heel expansion with the ST shoe did not differ significantly from when the horse was barefoot, in contrast with the significant restriction of the heel movement when a conventional shoe was used.

Mouldable, thermoplastic, glue-on frog-supportive shoes change hoof kinetics in normal and obese Shetland ponies.

BACKGROUND: Obesity and hyperinsulinaemia are frequently encountered in the equine population and risk factors for the development of laminitis. There are many options for hoof support that claim a beneficial effect, but often the scientific evidence is scarce. OBJECTIVES: To quantify the effect of frog-supportive shoes on hoof kinetics in normal and obese ponies. STUDY DESIGN: Controlled in vivo trial. METHODS: Ten Shetland mares (n = 10) with a normal (n = 5) or obese (n = 5) body condition were led over a dynamically calibrated pressure plate before (T0), immediately after (T1) and 72 h (T2) after application of the shoes. The following locomotor variables were measured: stance duration (StDur), vertical impulse (VI), peak vertical force (PVF), time to PVF and time from PVF to lift off. The hoof print was divided into a toe and heel region and the StDur toe-heel index was calculated. The toe-heel hoof balance curves of the vertical force were plotted throughout the stance phase. RESULTS: The VI and PVF increased significantly 72 h after application of the shoes, when compared with T0 and T1. The StDur toe-heel index and toe-heel balance curves were significantly different between the normal and obese ponies. These variables became more comparable between the groups after application of the frog-supportive shoes. MAIN LIMITATIONS: It would have been interesting to measure the effect of the shoe in patients with acute laminitis. However, this would have had major welfare implications. CONCLUSIONS: The obese ponies moved more carefully than the normal group, demonstrated by a decreased loading of the toe area. The data illustrate that the ponies became more comfortable 72 h after application of the shoes, with a pronounced effect in the obese group. Thus, these results suggest that frog-supportive shoes could be beneficial, especially for obese ponies.

Evaluation of direct Etest for antimicrobial susceptibility testing of bacteria isolated from synovial fluid of horses using enrichment bottles.

This study evaluated the Etest for direct antimicrobial susceptibility testing (AST) of bacteria from equine synovial specimens, incubated in BACTEC enrichment bottles. Ninety-four culture-positive broths were inoculated onto agar to directly determine the minimum inhibitory concentrations (MICs) of 13 antimicrobials, using the Etest (direct Etest). Results were compared with those obtained with the agar dilution reference method, the standard Etest, and the disc diffusion method, after subculture and standardisation of the inoculum. For categorical comparison of AST results, MICs were translated into susceptibility categories, using clinical breakpoints. The direct Etest predicted categorical susceptibility/resistance of bacteria from equine synovial fluid with acceptable accuracy (overall categorical agreement, 91%) and was more reliable than the disc diffusion test. The direct Etest was less accurate than the standard Etest for generating MICs ± 1 log dilution relative to the reference method (overall essential agreement, 69% vs. 89%). As the Etest generated a high percentage of inaccuracies with trimethoprim and sulfadiazine, these were less suitable antimicrobial agents for inclusion. In conclusion, the direct Etest reliably predicted the susceptibility of isolates from equine synovial fluid for the tested antimicrobials, except for trimethoprim and sulfadiazine. Since it did not require subculture and preparation of a standardised inoculum, direct Etest results were available at least 24 h earlier than with other methods, which could facilitate the diagnosis of synovial infections. However, when accuracy is prioritised over speed for MIC determination, the standard Etest is preferred over the direct Etest.

The preventive effects of two nutraceuticals on experimentally induced acute synovitis.

BACKGROUND: Nutraceuticals are often used in the management of equine osteoarthritis, but scientific evidence of their efficacy is lacking. OBJECTIVES: To study the preventive effects of two new nutraceuticals after the experimental induction of synovitis in comparison with positive and negative control treatments. STUDY DESIGN: Blinded, controlled, randomised experiment. METHODS: Twenty-four healthy Standardbred horses were randomly allocated to supplement AT (multi-ingredient, 28 days), supplement HP (collagen hydrolysate, 60 days), meloxicam (4 days) or placebo (60 days). Synovitis was induced in the right intercarpal joint by intra-articular injection of 0.5 ng lipopolysaccharide (LPS) of Escherichia coli while treatments were continued. Blood and synovial fluid were sampled before treatment, immediately prior to LPS injection, and at 8, 24 and 48 h post-injection. Synovial fluid samples were analysed for total nucleated cell count (TNCC), total protein (TP) and selected biomarkers (prostaglandin E2 [PGE2 ], interleukin-6 [IL-6], glycosaminoglycans [GAGs], type II collagen synthesis [CPII], matrix metalloproteinase [MMP]). Lameness was scored by visual examination and pressure plate analysis immediately prior to LPS injection, and at 8, 24 and 48 h post-injection. Clinical examinations were performed before treatment, immediately prior to LPS injection, at 2, 4 and 6 h post-injection, and then twice per day during the test period. RESULTS: Before treatment and intra-articular challenge, there were no statistically significant differences among the treatment groups for any of the parameters. After intra-articular challenge, the placebo group showed significantly higher synovial fluid TP, TNCC and PGE2 compared with the meloxicam group, although the model did not induce a relevant amount of lameness. Both nutraceuticals resulted in significantly lower synovial fluid TP, TNCC and PGE2 compared with placebo. No statistical differences in IL-6, GAGs, CPII or MMPs were observed among treatment groups. No adverse effects were observed. MAIN LIMITATIONS: Despite evidence of synovitis, lameness was too mild to detect. CONCLUSIONS: The preventive administration of these nutraceuticals showed anti-inflammatory effects in this validated synovitis model. Therefore, further studies of their clinical applicability are warranted.

Anatomical Description of the Presence and Variability of the Digital Manica Flexoria in the Equine Digital Flexor Tendon Sheath.

During endoscopy (tenoscopy) of the distal aspect of the equine digital flexor tendon sheath (DFTS), the digital manica flexoria can be visualized connecting the distal branches of the superficial digital flexor tendon. However, this structure has been inconsistently described and variably named in the veterinary literature. The objectives of this study were to describe the presence, configuration and variability of the digital manica flexoria in the equine distal limb. Dissection of 144 equine cadaveric limbs revealed the presence of this structure in all the feet, although different types and conformations were identified. In the forelimbs, a membranous digital manica flexoria predominated (94%; P < 0.001), in particular a synovial bridge type (83%; P < 0.001). In the hindlimbs, a tendinous digital manica flexoria predominated (93%; P < 0.001), in particular the oblique-crossing of tendinous bundles (61%; P < 0.001). Passage dorsal to the digital manica flexoria towards the distal DFTS was only possible in 22 of the 144 limbs, all forelimbs. Clinicians should be aware of the intra- and inter-individual anatomical variations of the digital manica flexoria to avoid misinterpretation during ultrasonographic and tenoscopic examinations of the DFTS.

Diffusion of mepivacaine to adjacent synovial structures after intrasynovial analgesia of the digital flexor tendon sheath.

REASONS FOR PERFORMING STUDY: Controversy exists about the specificity of diagnostic analgesia of the digital flexor tendon sheath (DFTS) in horses. OBJECTIVES: To evaluate the degree of diffusion of mepivacaine from the equine DFTS to adjacent synovial structures. STUDY DESIGN: Crossover experiment. METHODS: Under general anaesthesia, the DFTS of one front and one hindlimb of 8 horses were injected simultaneously with mepivacaine. Synovial fluid samples of the injected DFTS, the adjacent metacarpo-/metatarsophalangeal (MCP/MTP) joint, proximal interphalangeal joint, distal interphalangeal joint, navicular bursa and contralateral MCP/MTP joint were collected 15 min post injection (T15) from one of the injected limbs and 60 min post injection (T60) from the other limb. Venous blood samples were obtained at T0, T15 and T60 to evaluate systemic distribution of mepivacaine. After a 2-week washout period, the procedure was repeated using the same limbs but reversing the time of sampling (front vs. hindlimbs). The concentration of mepivacaine in samples was measured with a commercial ELISA kit. RESULTS: Mepivacaine concentrations in the DFTS samples, at both T15 (5077 mg/l) and T60 (3503 mg/l), exceeded those estimated sufficient to produce synovial analgesia (100 mg/l or 300 mg/l). Mepivacaine was found in all synovial structures adjacent to the injected DFTS and in the contralateral MCP/MTP joints, but concentrations were low, with a maximum value of only 3.2 mg/l. With the exception of the navicular bursa samples, the mepivacaine concentrations in the adjacent synovial structures were significantly higher at T60 than at T15 (P<0.03). Significantly higher mepivacaine concentrations were found in the ipsilateral than the contralateral MCP/MTP joints at T60 (P<0.001). Blood samples had significantly higher mepivacaine concentrations at T15 and T60 than at T0 (P<0.001). CONCLUSIONS: Mepivacaine injected into the DFTS of horses diffuses towards adjacent synovial structures without achieving clinically relevant concentrations.

The effect of perineural anaesthesia and handler position on limb loading and hoof balance of the vertical ground reaction force in sound horses.

REASONS FOR PERFORMING STUDY: The effects of handler position and perineural anaesthesia in sound horses need investigation to facilitate interpretation of pressure plate analysis in lame horses. OBJECTIVES: To evaluate the effect of handler position and perineural anaesthesia on limb loading and particularly hoof balance in sound horses. STUDY DESIGN: Nonrandomised crossover study. METHODS: Six sound horses were walked and trotted over a pressure plate, with the handler on the left and subsequently on the right side, and finally after a bilateral low palmar digital nerve block. One week later this procedure was repeated before and after a bilateral abaxial sesamoidean nerve block. Peak vertical force, vertical impulse and stance time of 5 hoof prints of both forelimbs were obtained (126 Hz), and toe-heel and mediolateral hoof balance curves of the vertical force were plotted throughout stance. Limb-loading and timing data and hoof balance data (beginning, middle and end of the stance phase) were statistically compared (handler left compared with right; before compared with after low palmar digital nerve block and abaxial sesamoidean nerve block; baseline at first measurement session compared with second). RESULTS: There were no significant effects of handler position and perineural anaesthesia on peak vertical force, vertical impulse and stance time. Hoof balance curves were not affected by handler position or perineural anaesthesia. The limb loading data and hoof balance curves were comparable for each horse over the one-week interval. CONCLUSIONS: Handler position and perineural anaesthesia do not have an effect on limb loading and toe-heel and mediolateral hoof balance in sound horses, which is of fundamental importance before embarking on pressure plate analysis for lameness diagnosis.

Genetic parameters for chronic progressive lymphedema in Belgian Draught Horses.

Genetic parameters for chronic progressive lymphedema (CPL)-associated traits in Belgian Draught Horses were estimated, using a multitrait animal model. Clinical scores of CPL in the four limbs/horse (CPLclin ), skinfold thickness and hair samples (hair diameter) were studied. Due to CPLclin uncertainty in younger horses (progressive CPL character), a restricted data set (D_3+) was formed, excluding records from horses under 3 years from the complete data set (D_full). Age, gender, coat colour and limb hair pigmentation were included as fixed, permanent environment and date of recording as random effects. Higher CPLclin certainty (D_3+) increased heritability coefficients of, and genetic correlations between traits, with CPLclin heritabilities (SE) for the respective data sets: 0.11 (0.06) and 0.26 (0.05). A large proportion of the CPLclin variance was attributed to the permanent environmental effect in D_full, but less in D_3+. Date of recording explained a proportion of variance from 0.09 ± 0.03 to 0.61 ± 0.08. Additive genetic correlations between CPLclin and both skinfold thickness and hair diameter showed the latter two traits cannot be used as a direct diagnostic aid for CPL. Due to the relatively low heritability of CPLclin , selection should focus on estimated breeding values (from repeated clinical examinations) to reduce CPL occurrence in the Belgian Draught Horse.

A preliminary study on pressure-plate evaluation of forelimb toe-heel and mediolateral hoof balance on a hard vs. a soft surface in sound ponies at the walk and trot.

REASONS FOR PERFORMING STUDY: Thus far, pressure-plate analysis has been limited to measurements on a hard surface, whereas equine athletes routinely perform on a deformable substrate. OBJECTIVES: To explore pressure-plate analysis on arena footing. STUDY DESIGN: Nonrandomised crossover study using noninvasive techniques. METHODS: Five sound, unshod ponies were walked and trotted over a pressure plate in 2 different conditions. In the first session, the plate was covered with only a 5 mm rubber mat, and in the second session, with an additional 50 mm layer of sand and synthetic fibres. Limb loading and timing variables (peak vertical force, vertical impulse, peak vertical pressure, hoof contact area and stance phase duration) were obtained. Toe-heel and mediolateral hoof balance of the vertical force were calculated throughout stance (126 Hz). RESULTS: Peak vertical force, vertical impulse, peak vertical pressure and stance phase duration were decreased on the soft substrate, while hoof contact area increased. At impact, there was more even load distribution between the toe and heel region on the soft vs. hard surface. At mid-stance, there was more loading of the toe region on the soft compared with the hard surface. At impact, there was more even load distribution between lateral and medial on the soft vs. hard surface at walk, but not at trot. CONCLUSIONS: Comparison of observed vs. expected impulse indicated that the main factor involved in the lower loading on the soft surface is the dampening effect of the soft substrate, although definitive conclusions require concurrent force-plate analysis. The pressure plate permitted quantitative evaluation of hoof balance of the vertical force on a deformable surface at the walk and trot and proved that there is more even load distribution on arena footing.

Distal limb desensitisation following analgesia of the digital flexor tendon sheath in horses using four different techniques.

REASONS FOR PERFORMING STUDY: Controversy exists about the desensitisation obtained after diagnostic analgesia of the digital flexor tendon sheath (DFTS) during lameness examinations. OBJECTIVES: To determine whether DFTS analgesia results in inadvertent desensitisation of the palmar/plantar digital nerves and whether this depends on the injection technique used. STUDY DESIGN: Crossover experimental study. METHODS: The DFTS of 9 horses were injected with local anaesthetic solution and radiodense contrast medium using one of the following techniques: Proximal (at lateral proximal recess of the DFTS), Axial (axial to the lateral proximal sesamoid bone), Base (at base of the lateral proximal sesamoid bone), and Distal (at palmar/plantar mid-pastern). In total, 72 injections were performed. Skin desensitisation at the heel bulbs was tested with a dynamometer before and at 15, 30, 90 and 120 min after injection. RESULTS: Overall, complete desensitisation of a heel bulb at one or more time points after injection occurred in 22 limbs (30.6%). An additional 7 limbs were partially desensitised. Complete skin desensitisation occurred in 10, 3, 4 and 5 limbs using the Proximal, Axial, Base and Distal techniques respectively. Significant differences between techniques were only found at T30. The probability of skin desensitisation at the heel bulbs was 4 times higher when using the Proximal compared with the Axial and Base techniques in the forelimbs, and 3 times higher compared with the Axial and Distal techniques in the hindlimbs. Skin desensitisation nearly always occurred exclusively on the lateral heel bulb. Bilateral desensitisation only occurred in 5 limbs. CONCLUSIONS: Anaesthesia of the palmar/plantar digital nerves with distal limb desensitisation often occurs after DFTS analgesia. A higher chance of desensitisation exists when injecting the proximal DFTS recess. It is advisable to verify skin sensitivity at the heel bulbs after DFTS analgesia to avoid false interpretations about the origin of pain causing lameness.

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.

Comparison of four techniques for synoviocentesis of the equine digital flexor tendon sheath: a cadaveric study.

OBJECTIVE: To compare four different techniques for synoviocentesis of the equine digital flexor tendon sheath (DFTS). METHODS: Fifteen inexperienced operators performed each of the following injection techniques on two cadaveric limbs: Proximal (at the proximal recess of the DFTS), Axial (axial to the proximal sesamoid bone), Base (at the base of the proximal sesamoid bone), and Distal (at the pastern). The number of attempts needed before the needle was assumed to be correctly positioned into the DFTS was recorded and 10 ml of methylene blue was injected. The limbs were dissected to determine the presence of methylene blue in the DFTS, the distance between the needle entrance point and the lateral palmar or plantar (digital) nerve, the degree of subcutaneous leakage and the distance between the border of the leakage zone and the lateral digital nerve. RESULTS: The Axial (29/30) and Distal (25/30) approaches had the highest numbers of successful injections. The median number of attempts was highest for the Axial approach. The distances from the injection point and from the border of the leakage zone to the lateral digital nerve were longer for Distal and Axial approaches. CLINICAL RELEVANCE: In the hands of inexperienced operators, the Axial approach was the most successful technique for injection of the equine DFTS. Sparse subcutaneous leakage and larger distance to the nerve when using this technique might decrease the risk of in-advertent palmar or plantar digital nerve desensitisation when performing DFTS analgesia.

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.

A pressure plate study on fore and hindlimb loading and the association with hoof contact area in sound ponies at the walk and trot.

The aim of this study was to evaluate the association between fore- and hind-hoof contact area and limb loading. Data from a previous study on forelimb loading and symmetry were compared with data on hindlimb kinetics, and the fore- and hind-hoof contact area at the walk and trot was evaluated. Five sound ponies, selected for symmetrical feet, were walked and trotted over a pressure plate embedded in a custom-made runway. The hindlimb peak vertical force (PVF) and vertical impulse (VI) were found to be significantly lower than in the forelimb, whereas their high symmetry ratios (>95%) did not show a significant difference from forelimb data. Hindlimb PVF in ponies was found to be slightly higher when compared to data reported for horses even though the ponies moved at a similar or lower relative velocity. The contact area had low intra-individual variability and was significantly smaller in the hind- than in the fore-hooves. A larger contact area was significantly associated with lower peak vertical pressure (PVP) but higher PVF and VI. No significant differences between left and right sides were found for contact area or loading variables. Pressure plate measurements demonstrated a significant association between hoof contact area and limb loading, in addition to intrinsic differences between fore and hindlimb locomotor function. The pressure plate provides the clinician with a tool to quantify simultaneously contralateral differences in hoof contact area and limb loading.