Recent Research Reports

List of Reports

Comparison of first and second acupuncture treatments in horses with chronic laminitis

Introduction: Laminitis is a common but critical disease that causes severe pain and disability in horses. The etiology and pathogenesis of laminitis remain inconclusive and a multimodal therapeutic approach is generally indicated. Acupuncture has been used as a treatment option; however, the required number of treatments is still controversial due to the lack of objective scientific evidence. The objective of this study was to determine if the response to a second acupuncture treatment differed from the response to the first acupuncture treatment in horses with chronic laminitis.
Material and Methods: Fourteen horses with chronic laminitis were identified. Acupuncture points were determined based on the results of a diagnostic acupuncture palpation examination. The second acupuncture treatment and lameness examination were conducted one week after the first treatment. Ten minutes after each acupuncture treatment, a lameness examination was performed and included an objective examination using a body-mounted inertial sensor system called "Lameness Locator" and a routine lameness examination following the "American Association of Equine Practitioners" (AAEP) lameness scale. The level of lameness was statistically analyzed using paired t-test and Wilcoxon signed rank test with p-values <0.05 considered significant.
Results: Both objective (P=0.042) and routine lameness examinations (P=0.027) showed that the level of lameness significantly decreased after the second acupuncture treatment compared to the response to the first treatment.
Discussion: The results of this study suggest that continued acupuncture treatments will result in increasing levels of pain relief, showing the advantage of performing more than one acupuncture treatment in horses with chronic laminitis.

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Characteristics of correlational patterns between equine hoof conformation and midstance kinetics

Conformational changes may distort stress distribution within the hoof and even proximal structures, consequently leading to pathologies; however, evidence-based research is limited. This study aimed to examine the correlation between hoof anatomy and midstance kinetics in healthy horses.
Materials and Methods: Arabian Horse (n=9) were led at walk over a pressure plate. Midstance force (F), contact pressure (CP) and contact area (CA) were measured at medial, lateral, dorsal and palmar region of the hoof. A total of 55 variables of internal (radiography) and external anatomy (conformational images) of the hoof were measured. Pairwise correlations between biomechanical and anatomical measurements were investigated by Pearson’s rank correlation coefficient. P-values ≤ 0.05 and r values ≥ 0.5 were considered.
Results: Our results revealed a negative correlation between CA and toe angle (r=-0.71). The toe F was negatively with several heel height measurements (0.63 ≤ r ≤ -0.58) implying an obvious trend. Larger medial wall angle was correlated with higher F, CP and CA on the medial aspect of the hoof (-0.68 ≤ r ≤ -0.58). Measurements of the dorsal hoof wall thickness and length/width of the distal phalanx (P3) showed correlations with F and CP (0.5 ≤ r ≤ 0.72) while the height of the P3 was negatively correlated with CA (r=0.72).
Discussion: These results confirmed the relationship between hoof anatomy and regional hoof kinetics. These findings support the circumstantial evidence that regional hoof kinetics is linked to changes of the hoof anatomy e.g., therapeutic trimming/shoein

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An evaluation of the effect of routine hoof trimming on hindhoof biomechanics at midstance in horses

The health of the equine hoof is essential to both a horse’s soundness and performance. Hoof balance has been of paramount importance to veterinarians, farriers, trainers, and horse owners. Biomechanical studies of the equine hoof are limited, yet studies have been focused on the forehoof (FH). The hindhoof (HH) has received less attention. Our objective was to examine force (F), contact pressure (CP) and contact area (CA) at the medial and lateral aspects of the HH and investigate the impact of routine hoof trimming on HH biomechanics.
Materials and Methods: Horses (n=9) were led at walk on a calibrated pressure plate before and after routine hoof trimming. The biomechanical variables F, CP, and CA at the medial and lateral aspects of the left HH were recorded before and after trimming at midstance. The differences between pre and post trimming data at these regions was examined using a Paired T-test. P-values <0.05 were considered significant.
Results: Among the measured variables, medial F (P=0.007) and medial CP (P=0.032) significantly increased (25% and 13%, respectively) after trimming. Our results showed significance differences between FH and HH data as well.
Discussion: Our results showed patterns of differences between medial and lateral aspects of the HH as well as the impact of trimming. Our findings provide valuable data on force and pressure distribution at different regions of the HH and indicate that biomechanics of the FH and HH differ. The HH biomechanics is unique and the difference from FH warrants further investigation.

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Morphovolumetric analysis of the equine hoof

Historically, conformation of the limbs has been used as a predictor of injury predisposition and athletic performance. Investigations have developed from a subjective visual assessment to increasingly quantitative methods; yet, volumetric (3D) data is missing. Functional anatomy of the hoof is intricate, and thus, its impact on musculoskeletal injuries is not well understood. Recognition of pathological changes within the hoof internal anatomy necessitates understanding of such relationship in normal/healthy hooves. This work aims to quantify the 3D anatomical relationships of the normal foot.
Materials and Methods: The T1-weighted MR images from 18 Standardbred horses (5.8 ± 2.6 years) with no known hoof pathologies were examined. Two 1 cm3 spheres were placed in image field and used for calibration. All measurements were performed using Image J software. Six volumetric and nine linear variables were measured. Pairwise correlations among measurements were examined using Pearson's product moment correlation coefficient and P values <0.05 were considered significant.
Results: Patterns of pairwise correlations were found. The distal phalanx volume (DP-V) was correlated with its width (r=0.739) but not its length. However, digital cushion volume) was correlated with its length (r=0.802). Navicular bone width was correlated with distal phalanx width (r=0.710) but not deep digital flexor tendon width (r=0.541). The DP-V and Total Hoof Volume were correlated with the weight of the horse.
Discussion/Conclusion: These data provide a basis for the use of morphogeometric analysis of the equine foot in investigation of clinical lameness, prevention of predisposed injuries and predicting future performance.

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The effect of routine hoof trimming on regional hoof kinetics

With each foot step equine hoof bares extreme forces from the weight of the animal and the ground reaction forces. Hoof balance is critical to absorb and dissipate such stresses. Historically, hoof balance has been primarily evaluated by visual assessment rather than an objective evaluation.
Materials and Methods: Ten sound horses were walked on a calibrated pressure plate before and after routine hoof trimming; the distribution of the force, pressure and contact area in mediolateral and toe-heel regions of the hoof were examined before and after trimming.
Results: We found that peak contact pressure at the toe increased about 21% after trimming; however, it only slightly (5%) decreased at the heel. Significant changes were found in the contact pressure (P=0.012) and peak contact pressure (P=0.013) at the toe region before and after hoof trimming.
Discussion: The greater pressure towards the toe and medial regions may help achieve gait stability and balance by shifting pressures from the heel and lateral soles. Asymmetrical force and pressure distribution will transfer the excess to more sensitive structures either within the hoof or towards more proximal structures, causing subsequent injury. Our results provide a benchmark for kinetic data on mediolateral and to-heel regions of the equine hoof which should be considered by farriers and veterinarians to better assess the horses’ hooves balance.

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Functional properties of the equine digital cushion in horses

The structural composition of regions of the digital cushion varies; such structural variations are correlated with the manner in which the digital cushion functions to absorb impact forces. Digital cushion (DC) has a more complicated structure contributing to its role in protecting internal structures than previously thought. However, the histological and functional properties of different regions of the equine DC have not been fully studied. Our objective was to examine the regional distribution of connective, nervous and adipose tissues, and vascular components of the DC in clinically sound hooves of Quarter Horses.
Materials and Methods: The DC samples from the axial proximal, axial distal, abaxial lateral, and abaxial medial regions of twenty-four Quarter Horses cadaver forehooves were collected, processed and stained with H&E, trichrome, and elastic stains. On each slide, a 3x3mm area was assessed by light microscopy. Statistical differences investigated using Kruskal-Wallis and Mann-Whitney tests with P-values <0.05 and <0.008 considered significant.
Results: The Axial distal region was characterized by the presence of significantly higher collagen (p<0.0001) and lower elastic fibers (p<0.0001) than axial proximal and abaxial regions. Almost four times as many nerve bundles were present in the axial proximal region as compared to the axial distal region.
Discussion: The regional structural differences of the digital cushion are presumably associated with different functional properties of those regions. Inability of the DC to protect sensitive internal structures, such as the navicular bone and related structures, when excessive/repeated forces are applied may initiate pathological changes.

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Quantitative analysis of the hoof in foals from birth to one year of age

The development of the foal foot has a unique pattern. Significant changes in external and internal anatomy of the foot occur at about 6 months of age which reflect transformation of the foot from a club-like, cylindrical conformation to a more angled, conical shape seen in adult horses. The juvenile foot grows rapidly with a radical change of shape, which reveals a unique developmental pattern that has not yet been fully studied. The goal of this study was to quantify external and internal anatomical characteristics of the foot throughout the first year of development.
Materials and Methods: Digital radiographs and photographs were taken bimonthly of the forefeet of 9 Arabian foals, beginning at 2 days of age until 12 months of age. Sixty-eight linear and angular variables were measured using Image J software. Statistical analyses were performed using piecewise random coefficient model and P values <0.05 were considered significant.
Results: Our findings identified distinct growth patterns in several external (conformational) measurements including hoof solar widths and lengths, palmar heel lengths, and toe and heel angles. Internal (radiographic) measurements included the widths and lengths of the phalanges and sesamoid bones as well as joint angles.
Discussion: Distinct changes in hoof development were identified at about 6 months of age. These findings describe when and how the foal foot transforms from a club-like, cylindrical conformation to a more angled, conical shape. This information is useful in discerning physiologic from pathologic changes in the foot of the growing foal.

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Fractures of the Distal Phalanx in Foals

Palmar process (PP) fractures of the distal phalanx in foals are far more common than previously reported. However, our knowledge of etiology, prevalence and predisposing factors is limited. The prevalence of distal phalanx PP fractures across 3 breeds and the relationship between hoof conformation and the incidence of fractures were evaluated.
Materials and Methods: Nineteen Thoroughbred, Quarter Horse and Arabian foals were examined from 2 to 12 months of age. Digital radiographs and photographs were obtained of the front hooves of these foals at two month intervals. Three individuals evaluated the radiographs for the presence of fractures. Measurements of the hoof and internal structures were made from the digital photographs and radiographs, respectively. Incidence of medial and lateral fractures between breeds was assessed by logistic regression. The relationship between measurements and the incidence of fractures was assessed by three-way ANOVA.  The significance was P ≤ 0.05.
Results: We found at least one fracture in 15 foals (74%) during the study period. Thoroughbred foals had the greatest number of fractures compared to the other breeds. Fracture incidence was highest in foals 6-8 months old. Dorsal distal phalanx length, hoof lateral angle and lateral palmar length were associated with a higher incidence of PP fractures.
Discussion: The results of this study showed variations in fracture prevalence between medial and lateral PPs, and across breeds. The differences might be explained by conformational variances. While most of those fractures are benign, the short and long term effects of PP fractures on horse health warrant further research.

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Evidence-Based Evaluation of Acupuncture Treatment in Chronic Equine Laminitis

Acupuncture treatment can improve the lameness and pain in horses suffering from chronic laminitis. Acupuncture can be performed along with other treatment options and should be considered in horses suffering from chronic laminitis. Severe pain and lameness are common sequel of laminitis. While acupuncture has been suggested to be effective for improving these clinical signs, the scientific evidence-based research is insufficient. The objective of this study was to compare the lameness level before and after two acupuncture treatments in horses with chronic laminitis.
Materials and Methods: Fourteen adult horses with chronic laminitis received two weekly acupuncture treatments including dry needling, hemo-acupuncture, and aqua-acupuncture. An objective lameness examination was performed using an inertial sensor-based lameness evaluation system (Lameness Locator): before, 10 minutes, one day, and one week after each acupuncture treatment. Statistical analyses were performed using paired t-test and Wilcoxon signed rank test and P values < 0.05 considered significant.
Results: The level of lameness from before the first acupuncture to one week after the second acupuncture treatment was significantly decreased (P=0.027). In addition, the lameness significantly improved (P=0.042) between 10 minutes after the first and second acupuncture treatments.
Discussion: The results of this study objectively showed the efficacy of acupuncture for improving the degree of lameness and pain associated with chronic equine laminitis. As acupuncture has minimal side effects and does not interfere with other treatments, it should be considered along with other treatment options for chronic equine laminitis.

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Changes in hoof kinetics and kinematics in response to regular hoof trimming

Proper hoof preparation and preserving hoof balance are integral to horses’ soundness and performance. Thus far, hoof balance is mainly assessed by visual examination which is not flawless. Modern Pressure plates (PP) can provide an objective evaluation of hoof biomechanics. The objective of this study was to assess the effect of hoof trimming on hoof biomechanics using a pressure plate.
Materials and Methods: Nine clinically sound Arabian horses were used in this study. Each horse was led across the PP by an experienced horse handler. A digital camera was positioned alongside the PP and foot strike and gait was recorded. For both hooves mid-stance, vertical force (N), contact pressure (Kpa), contact area (cm2), stance phase duration (s), swing phase duration (s), gait cycle duration (s), duty factor and swing phase were calculated. Kinetic and kinematic Data were analyzed using appropriate statistical test and P-value of ≤ 0.05 was considered significant.
Results: Among kinetic parameters vertical force increased from 1291 to 1508 N and contact pressure increased 115 to 134 kPa after trimming. Left and right hooves were not statistically different except for contact pressure. Among kinematics variables stance phase duration, swing phase duration and gait cycle duration decreased significantly.
Discussion/Conclusion: The observed changes in kinetic and kinematic parameters are related to hoof trimming. A better understanding of changes in post trim loading patterns requires further research.

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Use of Force Plate to investigate force distribution in foals with and without palmar processes fractures of the distal phalanx

Fractures of the palmar processes (PP) of the distal phalanx in foals are more common than previously thought. Clinical signs are often subtle and many fractures are missed using routine radiography. The goal of this study was to investigate the differences in force distribution in the front limbs of foals with without a history of PP fractures.
Material and Methods: Four foals were used in this study. Two foals had a history of bilateral and biaxial forelimb PP fractures and two foals were not diagnosed with PP fractures. Fractures were diagnosed using digital radiography. Foals were walked across a force plate and data were collected at impact, mid-stance and break-over phases. Peak vertical, transverse and longitudinal forces, as well as loading and unloading rates were recorded.
Results: In the foals with PP fractures, significantly higher peak vertical forces were found both at impact (P=0.002) and mid-stance (P=0.031) when compared to foals without fractures. Loading and unloading rates were significantly lower in foals with PP fractures (P=0.021 and P=0.0002, respectively).
Discussion/Conclusion: This study used a small sample size to, for the first time, examine force distribution in foals with confirmed forelimb PP fracture. Peak vertical force was greater in the foals with a PP fracture history. Faster loading and unloading rates in those foals implies shorter mid-stance phase. Assessment of PP fractures in foals with foot lameness is recommended for proper management and rehabilitation. The results of this study warrant further research using a larger sample size.

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Acupuncture Treatment in Horses with Chronic Laminitis: Comparing the First and Second Treatments

Laminitis is a common but critical disease that causes severe pain and disability in horses. The etiology and pathogenesis of laminitis remain inconclusive and multimodal treatment is generally indicated. The improvement of lameness by controlling the pain is a major concern for the owners and veterinarians. Acupuncture has been used as a treatment option; however, the efficacy of acupuncture and required number of treatments are still controversial due to the lack of objective scientific evidence. The objective of the present study was to examine if the response to the second acupuncture treatment differ from the response to the first treatment in horses with chronic laminitis.
Materials and Methods: Fourteen horses with chronic laminitis were selected within Southern California region. Age, breeds, gender, initial degree of lameness, and period of suffering varied. Laminitis was diagnosed by presence of definitive radiographic signs in addition to the clinical signs. For consistency, hemo-acupuncture: TH-1, SI-1, LI-1, Qian-ti-tou, and Qian-ti-tou mirror points and dry needling: LU-11, PC-9, HT-9, and Qian-ti-men were used as the treatment formula for these cases. Based on the results of diagnostic acupuncture palpation examination, additional points were selected for dry needling, hemo-acupuncture, and aqua-acupuncture for individual horses. For all horses, objective lameness examination using a body-mounted inertial sensor system called the “Lameness Locator” was performed 10 minutes after each acupuncture treatment. The second acupuncture and lameness evaluation were conducted likewise one week after the first acupuncture. The level of lameness was statistically analyzed via calculation of paired t-test and Wilcoxon signed rank test and p values < 0.05 were considered statistically significant.
Results: The degree of lameness after the first and second acupuncture treatments were evaluated. The level of lameness significantly decreased after second acupuncture treatment (P=0.042).
Discussion: The management of lameness and pain control in horses with chronic laminitis is a critical factor for rehabilitation and determining prognosis. The results of present study suggest that the addition of the second acupuncture treatment significantly diminished the level of lameness. Our data support performing more than one acupuncture treatment in horses with chronic laminitis; nonetheless, determining the number and frequency of acupuncture treatments warrant further research.

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Response to acupuncture treatment in horses: comparing the effect over time

Acupuncture (ACP) has been shown to be effective for alleviating pain of laminitic horses. However, little is known about the required time for the acupuncture treatment (ACPT) to be most effective. The objective of the present study was to determine if the alleviation of the pain and lameness differed when measured immediately, one day or one week after the ACPT in horses with chronic laminitis.
Materials and Methods: Following an initial ACP examination each of the enrolled fourteen laminitic horses received ACPT including: dry needling, bleeding, and aqua-acupuncture; depending on the nature of the problem and the location of the ACP points treated. Objective lameness examination (LE) using a body-mounted inertial sensor system (Lameness Locator) was performed immediately (within 10 minutes) (LE 1), one day (LE 2) and one week (LE 3) after the ACPT. The lameness level among LE1, LE2, and LE3 were compared using paired t-test and Wilcoxon signed rank test and P values <0.1 considered significant.
Results:The lameness level was significantly reduced (P=0.067) at LE2; nevertheless, it did not significantly vary between the LE 2 and LE 3 (P=0.857). We also found that the reduction in lameness levels were even more significant in horses with severe lameness (P=0.043).
Discussion: Our results showed that the lameness level significantly decreased one day after the ACPT but not immediately after the treatment; the lameness level did not further improve after one week. This suggests that it may take a while for the ACPT to be most effective.

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Detection of Fractures of the Palmar Processes of the Distal Phalanx in Young Foals

Without oblique radiographs 35% of palmar process fractures in foals will be missed. Cross sectional imaging and histopathology has confirmed a high incidence of palmar process (PP) fractures in foals. Obtaining good quality radiographs of foal hooves under field conditions is challenging. The availability of digital radiography has improved radiographic quality.
Materials and Methods: The fore feet of nineteen 6-8 months old foals were radiographed under field condition using a standard portable x-ray machine and a digital image acquisition system. Lateral, horizontal beam dorso-plamar and three oblique projections were made of each foot.
Results: Ten of nineteen foals were diagnosed with at last one fracture. Three foals had one or more fractures in each foot. Four foals had fractures of both the medial and lateral PP. If only the lateral and DP projections were evaluated, only 65% of the fractures were identified. The remaining 35% were identified only on one or more of the Dr60Pr-PaDiO and the two complex oblique projections.
Discussion: Fractures were identified in 53% of the subjects. Digital radiography has significantly improved radiographic quality in equine ambulatory practice, allowing immediate review of the images so that positioning abnormalities can be corrected and suspicious areas can be re-evaluated as necessary. Using proper diagnostic technique and good quality radiographs are critical in diagnosing PP fractures in foals as clinical signs can be easily missed. It has been reported that PP fractures may be associated with conformational abnormalities such as club footed conformation; however, the assessment of long term effect of PP fractures warrant further research.

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