Electromyography in the Horse: A Useful Technology?

Behavioral and physiological responses of horses to ground-based adaptive horsemanship lessons for veterans with post-traumatic stress disorder (PTSD)

Little literature exists on horses in adaptive horsemanship (AH) despite concerns about their well-being. The study objective was to evaluate behavioral and physiological responses of horses to ground-based AH lessons for veterans with post-traumatic stress disorder (PTSD). Lessons were expected to alter horses' hormone concentrations, behavior, and muscle activity. Geldings were assigned to AH (n=6; 20.3 ± 1.9 yrs., mean ± SE) or control (CON; stall in arena, n=6; 13.8 ± 1.7 yrs.) conditions for 8-week sessions based on current occupation (AH = equine-assisted services; CON = recreational riding). Plasma cortisol, epinephrine, norepinephrine, and oxytocin concentrations from samples at 0 (start of lesson), 3, 5, 25, and 30 (end) min were determined using assays validated in horses. Surface electromyography (sEMG) (masseter and brachiocephalic; Noraxon, Scottsdale, AZ, USA) and video were recorded continuously. Average rectified values (ARV) and median frequency (MF) were calculated (100 ms) after sEMG data were normalized, rectified, and filtered. The number, number of unique, and duration of stress related behaviors (ethogram) were recorded by three trained (ĸ ≥ 0.7) observers. Data were analyzed with repeated measures ANOVAs (significance P ≤ 0.05) with fixed effects of treatment, time point, week, and their interactions as appropriate and random effect of horse. CON horses had elevated cortisol concentrations (P = 0.0023) at 25 and 30 min. AH horses displayed fewer (P ≤ 0.0491) stress related and unique behaviors. CON horses were described as more (P < 0.0001) anxious, nervous, and stressed than AH horses (calm, comfortable, patient, and relaxed) in qualitative behavior analysis (22 observers). AH horses were less stressed than CON horses.

Effect of Clenbuterol on Muscle Activity During Exercise in Standardbred Horses

Clenbuterol (β₂ agonist) is a commonly administered bronchodilator in race and performance horses. While long-term administration can alter exercise performance and muscle properties, little is known about its effects on these parameters following short-term administration. A single dose of clenbuterol (0.80µg/kg) was expected to alter muscle activity of the extensor carpi radialis, semitendinosus, and longissimus dorsi during submaximal exercise. Eight mature Standardbred horses exercised for 2min at 5 m/s on a high-speed treadmill following clenbuterol dosing (clenbuterol) or no dosing (control) in a crossover experimental design. Surface electromyography (sEMG) data were collected continuously from the muscles of interest and processed to determine average rectified value (ARV) and median frequency (MF) of the signal during peak muscle activation (100ms period) during 15 strides. ARV data were log transformed. Data were analyzed with a mixed model ANOVA with fixed effects of period and treatment and a random effect of horse. No differences (p>0.05) in amplitude (ARV) or frequency (MF) of the EMG signal were detected following clenbuterol administration. Thus, a one-time dose of clenbuterol had no statistically detectable effect on muscle activity during submaximal exercise. Further studies should be under-taken to confirm these results and examine the effects of long-term administration on muscle activity during exercise.

Laryngeal reinnervation using the spinal accessory nerve: Electromyographic study of the sternomandibularis muscle

BACKGROUND

Selective laryngeal reinnervation using the first and second cervical nerve (C1C2) is a treatment option for recurrent laryngeal neuropathy that aims to restore the function of the cricoarytenoideus dorsalis muscle (CAD). Despite the technique's satisfying success rate, it has several limitations. These triggered the search for another potential donor nerve that could reduce CAD muscle fatigue and shorten rehabilitation. The ventral branch of the spinal accessory nerve, providing motor innervation to the sternomandibularis (SM) muscle, was identified as a potentially well adapted nerve.

OBJECTIVES

To gather normative data from SM muscle activity induced by physiological spinal accessory nerve stimulation at rest and during exercise, and to determine SM muscle activity and fibre type recruitment relative to posture, gait, and respiratory cycle.

STUDY DESIGN

Clinical observational study.

METHODS

Surface electromyography of the SM muscle was performed in 9 horses: trained warmbloods, Thoroughbreds and Standardbreds. Signals were recorded in different feeding postures and at exercise, which included standardised treadmill exercise tests, lungeing and ridden work.

RESULTS

Timing of the SM muscle contraction coincided with inspiration at gallop. Intra-individual mean SM muscle activity increased with exercising speed (4 times higher in Thoroughbreds at gallop compared to walk and 7 times higher in Standardbreds at high-speed trot compared to walk). Moreover, the SM muscle was strongly activated at rest when the horse was grazing (7 times more compared to when it was eating out of a hay net or stable feeder). Frequency domain analysis revealed a predominant type I muscle fibre recruitment during feeding and at exercise (Type I muscle fibre activity was at least 2.5 times higher than type II muscle fibre activity).

MAIN LIMITATIONS

Lack of reference data on equine electromyography.

CONCLUSIONS

This study confirmed the potentially advantageous properties of the spinal accessory nerve for laryngeal reinnervation.

Adverse effects of polymyxin B administration to healthy horses

BACKGROUND

Polymyxin B (PolyB) is used to treat endotoxemia in horses; neurologic and nephrogenic adverse effects occur in humans.

OBJECTIVES

To describe PolyB adverse effects in horses.

ANIMALS

Five healthy horses (ataxia 0/5), 1 horse with cervical osteoarthritis (ataxia 1/5).

METHODS

Prospective blinded randomized cross-over trial; 3-weeks wash out. Horses received PolyB (PolyB 6000 IU/kg IV, 7 doses q12h, n = 6) and PolyB/gentamicin (PolyB 6000 IU/kg IV, q12h 7 doses; gentamicin 10 mg/kg IV q24h 4 doses n = 4, or q12-24 h 5 doses because of an additional erroneous dose, n = 2). Daily neurological examinations were video recorded, and ataxia graded by 3 observers. Urine status, urinary GGT/creatinine ratio, plasma creatinine, and urea were assessed every other day, EMG daily. Mixed model analysis was used to evaluate factors associated with ataxia grade and [PolyB].

RESULTS

Median ataxia score increased from 0/5 (range 0-2/5) to 2/5 (range 1-3/5) during administration and declined to 0.5/5 (range 0-2/5) after cessation. Gentamicin co-administration (P < .01, effect size: .8), number of PolyB doses (P < .001, effect size: .6), and time since last PolyB dose (P < .001, effect size: .5) had a significant effect on ataxia grades, while horse, day, [Genta], [PolyB], and [PolyB]CSF did not. Gentamicin co-administration and [Genta] Cpeak had no effect on median [PolyB] Cpeak (4.67 and 4.89 μg/ml for PolyB and PolyB/gentamicin, respectively). Urinary GGT/creatinine ratio was elevated in 3/6 horses receiving PolyB/gentamicin. The EMG remained unchanged.

CONCLUSIONS AND CLINICAL IMPORTANCE

PolyB caused transient ataxia, worsening with cumulative PolyB doses and gentamicin co-administration. Nephrotoxicity of PolyB was only evident when gentamicin was co-administered.

Electromyography of the Multifidus Muscle in Horses Trotting During Therapeutic Exercises

Thoracolumbar pain has been identified in both human and equine patients. Rehabilitation and conditioning programs have focused specifically on improving trunk and abdominal muscle function (1–5). Equine exercise programs routinely incorporate ground poles and training devices for the similar goals of increasing spinal and core stability and strength (6–8). The multifidus muscle has been an area of focus due to atrophy associated with disease (9). To date, there have been no reports on the activity of the multifidus muscle in horses in relation to therapeutic exercises. Our objectives were to use electromyography to determine the average work performed and peak muscle activity of the multifidus in horses trotting, trotting over ground poles, trotting while wearing a resistance band-based training device and trotting while wearing the training device over ground poles. We hypothesized that ground poles and the training device would each increase average work performed and peak multifidus muscle activity. Right and left cranial thoracic locations showed significant increased muscle work and peak activation when horses were trotted over ground poles versus without. The peak activation was significantly greater in horses trotting over poles in both lumbar regions, but there was no significant change in peak activation in either location due to the training device. When the influence of the training device was investigated without ground poles, left caudal thoracic muscle work and peak activity, and right lumbar muscle work were significantly lower when using the training device, as compared to without. When the training device was combined with trotting over ground poles, both left and right caudal thoracic regions showed significantly lower muscle work and peak activity when the device was used. There was no significant difference between with and without the device in either left or right lumbar muscle work. In conclusion, implementing ground poles can be an effective strategy to increase the activation of the multifidus muscle, however, caution should be taken when incorporating the use of a resistance band training device as muscle work and peak activation were significantly reduced in most locations. Further study should be performed in regards to the training device to determine its effects on epaxial musculature.

A Preliminary Study on the Use of HD-sEMG for the Functional Imaging of Equine Superficial Muscle Activation during Dynamic Mobilization Exercises

Superficial skeletal muscle activation is associated with an electric activity. Bidimensional High-Density Surface Electromyography (HD-sEMG) is a non-invasive technique that uses a grid of equally spaced electrodes applied on the skin surface to detect and portray superficial skeletal muscle activation. The goal of the study was to evaluate the feasibility of HD-sEMG to detect electrical activation of skeletal muscle and its application during rehabilitation exercises in horses. To fulfil this aim, activation of the superficial descending pectoral and external abdominal oblique core muscles were measured using HD-sEMG technology during dynamic mobilization exercises to induce lateral bending and flexion/extension tasks of the trunk. Masseter muscle was instrumented during mastication as a control condition. A 64 surface EMG channel wireless system was used with a single 64 electrode grid or a pair of 32 electrode grids. HD-sEMG provided unique information on the muscular activation onset, duration, and offset, along each motor task, and permitting inferences about the motor control strategy actuated by the central nervous system. Signals were further processed to obtain firing frequencies of few motor-neurons. Estimation of electromyographic amplitude and spectral parameters allowed detecting the onset of muscular fatigue during the motor tasks performed. HD-sEMG allows the assessment of muscular activation in horses performing specific motor tasks, supporting its future application in clinical and research settings.

Muscular tension as an indicator of acute stress in horses

Horses' muscular tension during acute stress remains unexplored. Our aim was to assess muscular, behavioral, cortisol, and hematocrit responses to social isolation (ISO), novel object exposure (NOV), and sham clipping (CLIP). Altered stress responses were expected. Eight mature Standardbred horses (four mares and four geldings) were exposed to acute stressors and a control period (CON) in a balanced, replicated 4×4 Latin Square experimental design with 3 min treatment periods and 10 min washout periods. Surface electromyography collected from the masseter, brachiocephalas, cervical trapezius, and longissimus dorsi was processed to derive average rectified value (ARV) and median frequency (MF) during the initial, middle, and final 30 s of treatments. ARV and MF data were log transformed then analyzed using a mixed model, repeated measures ANOVA along with plasma cortisol and hematocrit. Behavior data were analyzed using a negative binomial distribution mixed model ANOVA. CLIP resulted in greater (p < 0.05) log ARV in the masseter (1.5 + 1.5%, mean + SD) and brachiocepahlas (2.2 + 2.0%) than CON (-1.2 + 1.4%, 0.1 + 1.5%). ISO resulted in greater (p < 0.05) log ARV in the masseter (0.2 + 1.3%) and cervical trapezius (0.6 + 1.3%) than CON (-1.2 + 1.4%, -1.0 + 1.7%). ISO increased (p < 0.05) the total number of stress-related behaviors and hematocrit. No changes in cortisol were observed. We suggest that muscular tension can be used as an indicator of acute stress in horses. Incorporating muscle activity into an array of measurements may provide a more nuanced understanding of stress responses.

Selection of Image Texture Analysis and Color Model in the Advanced Image Processing of Thermal Images of Horses following Exercise

Simple Summary

Detecting horse state after exercise is critical for maximizing athletic performance. The horse’s response to fatigue includes exercise termination or exercise continuation at a lower intensity, which significantly limit the results achieved in races and equestrian competition. As conventional methods of detecting and quantifying exercise effort have shown some limitations, infrared thermography was proposed as a method of contactless detection of exercise effect. The promising correlation between body surface temperature and exercise-dependent blood biomarkers has been demonstrated. As the application of conventional thermography is limited by low specificity, advanced thermal image analysis was proposed here to visualize the link between blood biomarkers and texture of thermal images. Twelve horses underwent standardized exercise tests for six consecutive days, and both thermal images and blood samples were collected before and after each test. The images were analyzed using four color models (RGB, red-green-blue; YUV, brightness-UV-components; YIQ, brightness-IQ-components; HSB, hue-saturation-brightness) and eight texture-features approaches, including 88 features in total. In contrast to conventional temperature measures, as many as twelve texture features in two color models (RGB, YIQ) were linked with blood biomarker levels as part of the horse’s response to exercise.

Abstract

As the detection of horse state after exercise is constantly developing, a link between blood biomarkers and infrared thermography (IRT) was investigated using advanced image texture analysis. The aim of the study was to determine which combinations of RGB (red-green-blue), YUI (brightness-UV-components), YIQ (brightness-IQ-components), and HSB (hue-saturation-brightness) color models, components, and texture features are related to the blood biomarkers of exercise effect. Twelve Polish warmblood horses underwent standardized exercise tests for six consecutive days. Both thermal images and blood samples were collected before and after each test. All 144 obtained IRT images were analyzed independently for 12 color components in four color models using eight texture-feature approaches, including 88 features. The similarity between blood biomarker levels and texture features was determined using linear regression models. In the horses’ thoracolumbar region, 12 texture features (nine in RGB, one in YIQ, and two in HSB) were related to blood biomarkers. Variance, sum of squares, and sum of variance in the RGB were highly repeatable between image processing protocols. The combination of two approaches of image texture (histogram statistics and gray-level co-occurrence matrix) and two color models (RGB, YIQ), should be considered in the application of digital image processing of equine IRT.

An initial investigation into the effects of the equine transeva technique (pulsating current electrotherapy) on the equine Gluteus superficialis

The equine transeva technique (ETT), is a novel electrotherapy, which utilises pulsating current electrotherapy to target sensory and motor neurons. The technique may facilitate increased circulation and correction of musculoskeletal issues and injuries, such as tendon and ligament tears and muscle atrophy. Despite the importance of understanding the impact of ETT on horses, no current scientific research exists in this area. This preliminary study investigated the effects of ETT on the musculoskeletal system of the horse, specifically within the Gluteus superficialis (GS). Using surface electromyography, muscle workload was measured in 11 sound and healthy horses of varying breeds and disciplines within the inclusion criteria. Integrated electromyography (iEMG) calculated the percentage change in maximal contractions before and after ETT treatment during one minute trials at 30 s intervals. An ANCOVA determined if these constituted significant changes (Bonferroni adjusted alpha: P≤0.02). Significant differences in muscle workload were found on the left side between pre- and post-treatment readings across trials (P≤0.02), however no significant changes occurred for the right side. The majority of horses (82%; n=9) experienced bilateral changes, with 78% of these (n=7) exhibiting a negative change in muscle workload recorded from the pretreatment condition, which may indicate muscular relaxation. The results suggest ETT may have some effect on muscle workload in the athletic horse, however further research is needed to confirm the effects observed. Future studies should include randomising the side which is treated first, a larger sample size, expansion of temporal variables and consideration of a longitudinal study to determine if these trends accrue over multiple maintenance-purposed treatments.

The Effect of Ground Poles and Elastic Resistance Bands on Longissimus Dorsi and Rectus Abdominus Muscle Activity During Equine Walk and Trot

Core strengthening and postural stability are desired outcomes of certain therapeutic exercises performed in horses. This study aimed to quantify changes in muscle activation at a walk and trot in horses traveling over eight consecutive ground poles evenly spaced (at 30 inches for walk and 48 inches for trot) in parallel fashion in a straight line, and with hindquarter and abdominal elastic resistance bands applied at 25% stretch. Surface electromyography (sEMG) data were collected for the longissimus dorsi and rectus abdominus muscles in six horses. A 2 × 2 repeated measures ANOVA was performed for each muscle to test for significant differences in differences in normalized average rectified values and maximum low pass signals. Within subject effects were reported, followed by post-hoc pairwise comparisons to evaluate differences between the conditions of with or without ground poles or elastic resistance bands. The use of ground poles at a walk resulted in a significant (p < .05) increase in the maximum low pass value bilaterally in the longissimus dorsi and rectus abdominus muscles, with an increase in the average rectified value bilaterally in the rectus abdominus muscles and right longissimus dorsi muscle. The use of ground poles at a trot resulted in a significant increase in the maximum low pass value bilaterally in the rectus abdominus muscles. The hindquarter and abdominal elastic resistance bands resulted in a respective 27% and 27.2% increase in the mean average rectified value of the left and right RA muscles; however this only reached statistical significance in the left RA (p < .05). These findings provide support regarding changes in muscle activation when using ground poles to increase core and epaxial muscle engagement. While a significant effect on core muscle activation was identified with the elastic resistance bands at a trot, further research is needed in this area to further characterize their effects on muscle activation.

Horse Jumping and Dressage Training Activity Detection Using Accelerometer Data

Equine training activity detection will help to track and enhance the performance and fitness level of riders and their horses. Currently, the equestrian world is eager for a simple solution that goes beyond detecting basic gaits, yet current technologies fall short on the level of user friendliness and detection of main horse training activities. To this end, we collected leg accelerometer data of 14 well-trained horses during jumping and dressage trainings. For the first time, 6 jumping training and 25 advanced horse dressage activities are classified using specifically developed models based on a neural network. A jumping training could be classified with a high accuracy of 100 %, while a dressage training could be classified with an accuracy of 96.29%. Assigning the dressage movements to 11, 6 or 4 superclasses results in higher accuracies of 98.87%, 99.10% and 100%, respectively. Furthermore, during dressage training, the side of movement could be identified with an accuracy of 97.08%. In addition, a velocity estimation model was developed based on the measured velocities of seven horses performing the collected, working, and extended gaits during a dressage training. For the walk, trot, and canter paces, the velocities could be estimated accurately with a low root mean square error of 0.07 m/s, 0.14 m/s, and 0.42 m/s, respectively.

β-Hydroxy β-methylbutyrate supplementation to adult Thoroughbred geldings increases type IIA fiber content in the gluteus medius

Consumption of β-hydroxy β-methylbutyrate (HMB) alters muscle composition and metabolism leading to strength and agility improvements in human athletes. To determine if HMB affects athletic performance and muscle function in horses, Thoroughbred geldings were fed a control (CON; n = 5) or HMB (n = 6) supplement for 6 wk prior to completing a standardized exercise test (SET). Gluteus medius (GM) muscle biopsies were obtained before the SET for fiber typing. Heart rate, biceps femoris (BF) and semitendinosus (ST) surface electromyograms (EMG), and fore and hind limbs metacarpophalangeal joint angles were captured at the gallop of the SET. Results demonstrate that HMB supplementation increased (P < 0.05) the percentage of type IIA and IIA/X muscle fibers in the GM with a corresponding decrease (P < 0.05) in type IIX fibers. The percentage of type I fibers was unaffected by diet. Supplementation with HMB did not result in any measurable effects on performance or biomechanical properties by comparison to CON. Supplementation with HMB resulted in an increase (P < 0.05) in ST median frequency at speeds of 10 m/s and greater. Increasing treadmill speed resulted in an increase (P < 0.05) in stride length and the maximal proximal forelimb fetlock angle, and a decrease (P < 0.05) in stance phase time of the gait cycle. Integrated EMG (iEMG) increased (P < 0.05) with increasing treadmill speeds for both the BF and ST with the BF exhibiting greater (P < 0.05) iEMG values than the ST. In summary, HMB increased the percentage of type IIA GM fibers, which did not translate into improved performance.

Driftage: a multi-agent system framework for concept drift detection

BACKGROUND

The amount of data and behavior changes in society happens at a swift pace in this interconnected world. Consequently, machine learning algorithms lose accuracy because they do not know these new patterns. This change in the data pattern is known as concept drift. There exist many approaches for dealing with these drifts. Usually, these methods are costly to implement because they require (i) knowledge of drift detection algorithms, (ii) software engineering strategies, and (iii) continuous maintenance concerning new drifts.

RESULTS

This article proposes to create Driftage: a new framework using multi-agent systems to simplify the implementation of concept drift detectors considerably and divide concept drift detection responsibilities between agents, enhancing explainability of each part of drift detection. As a case study, we illustrate our strategy using a muscle activity monitor of electromyography. We show a reduction in the number of false-positive drifts detected, improving detection interpretability, and enabling concept drift detectors' interactivity with other knowledge bases.

CONCLUSION

We conclude that using Driftage, arises a new paradigm to implement concept drift algorithms with multi-agent architecture that contributes to split drift detection responsability, algorithms interpretability and more dynamic algorithms adaptation.

Measuring Farm Animal Emotions-Sensor-Based Approaches

Understanding animal emotions is a key to unlocking methods for improving animal welfare. Currently there are no 'benchmarks' or any scientific assessments available for measuring and quantifying the emotional responses of farm animals. Using sensors to collect biometric data as a means of measuring animal emotions is a topic of growing interest in agricultural technology. Here we reviewed several aspects of the use of sensor-based approaches in monitoring animal emotions, beginning with an introduction on animal emotions. Then we reviewed some of the available technological systems for analyzing animal emotions. These systems include a variety of sensors, the algorithms used to process biometric data taken from these sensors, facial expression, and sound analysis. We conclude that a single emotional expression measurement based on either the facial feature of animals or the physiological functions cannot show accurately the farm animal's emotional changes, and hence compound expression recognition measurement is required. We propose some novel ways to combine sensor technologies through sensor fusion into efficient systems for monitoring and measuring the animals' compound expression of emotions. Finally, we explore future perspectives in the field, including challenges and opportunities.

Do Muscle Activities of M. Splenius and M. Brachiocephalicus Decrease Because of Exercise-Induced Fatigue in Thoroughbred Horses?

Muscle activities of the major hindlimb muscles have been reported to decrease with fatigue in horses. However, those in other muscles have been scarcely reported. We aimed to quantify fatigue-induced electromyographic changes in head and neck muscles and muscles around the shoulder joints in horses. Surface electromyographic recording of the splenius, brachiocephalicus, infraspinatus, and deltoid muscles was performed on a total of nine healthy Thoroughbred horses. Horses galloped on a treadmill inclined to 3% at a constant speed (12.7-14.6 m/second) to make them fatigued after approximately 5 minutes. They trotted at 3.5 m/second before and after this exercise. Stride frequency, integrated electromyographic values for a stride, and median frequency of the muscle discharge were calculated every 30 seconds. These parameters were compared at the start and end of the gallop exercise for the lead and trailing limbs and while trotting before and after the exercise using a paired t-test. The stride frequency significantly decreased at the end of the gallop (P < .001), whereas it did not change while trotting. Integrated electromyographic values of the splenius and brachiocephalicus muscles in both lead and trailing limbs at the gallop and those of both left and right sides at the trot significantly decreased with fatigue (P < .05), whereas those of infraspinatus and deltoid muscles did not change at either gallop or trot. No changes were observed in median frequency in any muscles with fatigue. These results suggest that splenius and brachiocephalicus muscle activities can be associated with stride frequency and speed.

State-of-the-Art Diagnostic Methods to Diagnose Equine Spinal Disorders, With Special Reference to Transcranial Magnetic Stimulation and Transcranial Electrical Stimulation

Spinal cord disorders are a common problem in equine medicine. However, finding the site of the lesion is challenging for veterinarians because of a lack of sensitive diagnostic methods that can assess neuronal functional integrity in horses. Although medical imaging is frequently applied to help diagnose corticospinal disorders, this approach does not reveal functional information. For the latter, transcranial magnetic stimulation (TMS) and more recently transcranial electrical stimulation (TES) can be useful. These are brain stimulation techniques that create either magnetic or electrical fields passing through the motor cortex, inducing muscular responses, which can be recorded either intramuscularly or extramuscularly by needle or surface electrodes. This permits the evaluation of the functional integrity of the spinal motor tracts and the nerve conduction pathways. The interest in TES in human medicine emerged these last years because unlike TMS, TES tends to bypass the motor cortex of the brain and predominantly relies on direct activation of corticospinal and extrapyramidal axons. Results from human medicine have indicated that TMS and TES recordings are mildly if not at all affected by sedation. Therefore, this technique can be reliably used in human patients under either sedation or full anesthesia to assess functional integrity of the corticospinal and adjunct motor tracts. This opens important new avenues in equine medicine.

Effect of water depth on muscle activity of dogs when walking on a water treadmill

Evidence-informed practice is currently lacking in canine hydrotherapy. This study aimed to investigate if the estimated workload of the gluteus medius (GM) and longissimus dorsi (LD) increased in dogs at different water depths when walking on a water treadmill. Seven dogs were walked for 2 min continuously on a water treadmill at depths of no submersion (depth 1), mid-tarsal (depth 2), between lateral malleolus and lateral epicondyle (depth 3) and between the lateral epicondyle and greater trochanter (depth 4). Continuous electromyographic data from the right and left sides of GM and LD were collected simultaneously during exercise. Friedman’s analyses with post-hoc Wilcoxon tests established if significant differences in GM and LD muscle activity occurred between the water depths for mean estimated-workload. Significant differences occurred in estimated-workload in GM and LD between water depths (P<0.05). Mean estimated-workload decreased in the right and left GM between depths 2 (mid-tarsal) and 3 (between lateral malleolus and epicondyle) (P<0.007) and depths 2 and 4 (between lateral epicondyle and greater trochanter) (P<0.001), a pattern which was repeated for left and right LD (P<0.007). Right GM mean estimated-workload increased between depth 1 (no submersion) and depth 2 only (P<0.013). Water depth influences GM and LD activity in dogs walking on a water treadmill. Increasing knowledge of canine locomotion in water treadmills could be used to inform individualised rehabilitation regimes for dogs undertaking hydrotherapy.

The Efficacy of Intermittent Long-term Bell Boot Application for the Correction of Muscle Asymmetry in Equine Subjects

It has been proposed that manipulating proprioceptive signals of the equine distal limb as part of a rehabilitation process in cases of musculoskeletal pain or neurologic deficits can be used to correct postural control and restore normal motor programs. This trial has examined the effect of treatment with a light-weight and loose-fitting bell boot (82 g) on an imbalance of muscle gluteus superficialis function in horses as measured using acoustic myography (AMG). Eight horses were trained over a 60-minute period every 3 days for 6 weeks, a protocol based on preliminary findings. Acoustic myography measurements, recording the coordination, spatial and temporal summation of muscle contractions, were made at the start (baseline) and at the finish (week 6) after a warmup period and following a set procedure of physical activity. Walking, trotting, and cantering during a left-hand circle at the start of the trial revealed a slight but significant asymmetry between the left and right hind limb muscle, which improved successfully after 6 weeks of proprioception training. Data for the right-hand circle, which revealed no significant asymmetry, during walk, trot, and canter at the start, showed no change after 6 weeks of training at the walk and trot but developed an imbalance during cantering, the result of overcompensation. This study demonstrates that functional musculoskeletal asymmetry measured during periods of activity can not only be accurately detected using AMG but it also reveals an association between the program of proprioceptive training adopted and an improvement in muscular imbalance.