Reliability of surface electromyographic (sEMG) measures of equine axial and appendicular muscles during overground trot

The reliability of surface electromyography (sEMG) has not been adequately demonstrated in the equine literature and is an essential consideration as a methodology for application in clinical gait analysis. This observational study investigated within-session, intra-subject (stride-to-stride) and inter-subject reliability, and between-session reliability of normalised sEMG activity profiles, from triceps brachii (triceps), latissimus dorsi (latissimus), longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus muscles in n = 8 clinically non-lame horses during in-hand trot. sEMG sensors were bilaterally located on muscles to collect data during two test sessions (session 1 and 2) with a minimum 24-hour interval. Raw sEMG signals from ten trot strides per horse and session were DC-offset removed, high-pass filtered (40 Hz), full-wave rectified, and low-pass filtered (25 Hz). Signals were normalised to peak amplitude and percent stride before calculating intra- and inter-subject ensemble average sEMG profiles across strides for each muscle and session. sEMG profiles were assessed using waveform similarity statistics: the coefficient of variation (CV) to assess intra- and inter-subject reliability and the adjusted coefficient of multiple correlation (CMC) to evaluate between-session reliability. Across muscles, CV data revealed that intra-horse sEMG profiles within- and between-sessions were comparatively more reliable than inter-horse profiles. Bilateral gluteal, semitendinosus, triceps and longissimus (at T14 and L1) and right biceps showed excellent between-session reliability with group-averaged CMCs > 0.90 (range 0.90–0.97). Bilateral latissimus and left biceps showed good between-session reliability with group-averaged CMCs > 0.75 (range 0.78–0.88). sEMG profiles can reliably describe fundamental muscle activity patterns for selected equine muscles within a test session for individual horses (intra-subject). However, these profiles are more variable across horses (inter-subject) and between sessions (between-session reliability), suggesting that it is reasonable to use sEMG to objectively monitor the intra-individual activity of these muscles across multiple gait evaluation sessions at in-hand trot

Adaptations in equine axial movement and muscle activity occur during induced fore- and hindlimb lameness: a kinematic and electromyographic evaluation during in-hand trot

Background: The inter-relationship between equine thoracolumbar motion and muscle activation during normal locomotion and lameness is poorly understood. Objective: To compare thoracolumbar and pelvic kinematics and longissimus dorsi (longissimus) activity of trotting horses between baseline and induced forelimb (iFL) and hindlimb (iHL) lameness. Study design: Controlled experimental cross-over study. Methods: Three-dimensional kinematic data from the thoracolumbar vertebrae and pelvis, and bilateral surface electromyography (sEMG) data from longissimus at T14 and L1, were collected synchronously from clinically nonlame horses (n = 8) trotting overground during a baseline evaluation, and during iFL and iHL conditions (2–3/5 AAEP), induced on separate days using a lameness model (modified horseshoe). Motion asymmetry parameters, maximal thoracolumbar flexion/extension and lateral bending angles, and pelvis range of motion (ROM) were calculated from kinematic data. Normalised average rectified value (ARV) and muscle activation onset, offset and activity duration were calculated from sEMG signals. Mixed model analysis and statistical parametric mapping compared discrete and continuous variables between conditions (α = 0.05). Results: Asymmetry parameters reflected the degree of iFL and iHL. Maximal thoracolumbar flexion and pelvis pitch ROM increased significantly following iFL and iHL. During iHL, peak lateral bending increased towards the nonlame side (NLS) and decreased towards the lame side (LS). Longissimus ARV significantly increased bilaterally at T14 and L1 for iHL, but only at LS L1 for iFL. Longissimus activation was significantly delayed on the NLS and precipitated on the LS during iHL, but these clear phasic shifts were not observed in iFL. Main limitations: Findings should be confirmed in clinical cases. Conclusions: Distinctive, significant adaptations in thoracolumbar and pelvic motion and underlying longissimus activity occur during iFL and iHL and are detectable using combined motion capture and sEMG. For iFL, these adaptations occur primarily in a cranio-caudal direction, whereas for iHL, lateral bending and axial rotation are also involved

Adaptations in equine appendicular muscle activity and movement occur during induced fore- and hindlimb lameness: An electromyographic and kinematic evaluation

The relationship between lameness-related adaptations in equine appendicular motion and muscle activation is poorly understood and has not been studied objectively. The aim of this study was to compare muscle activity of selected fore- and hindlimb muscles, and movement of the joints they act on, between baseline and induced forelimb (iFL) and hindlimb (iHL) lameness. Three-dimensional kinematic data and surface electromyography (sEMG) data from the fore- (triceps brachii, latissimus dorsi) and hindlimbs (superficial gluteal, biceps femoris, semitendinosus) were bilaterally and synchronously collected from clinically non-lame horses ( n = 8) trotting over-ground (baseline). Data collections were repeated during iFL and iHL conditions (2-3/5 AAEP), induced on separate days using a modified horseshoe. Motion asymmetry parameters and continuous joint and pro-retraction angles for each limb were calculated from kinematic data. Normalized average rectified value (ARV) and muscle activation onset, offset and activity duration were calculated from sEMG signals. Mixed model analysis and statistical parametric mapping, respectively, compared discrete and continuous variables between conditions (α= 0.05). Asymmetry parameters reflected the degree of iFL and iHL. Increased ARV occurred across muscles following iFL and iHL, except non-lame side forelimb muscles that significantly decreased following iFL. Significant, limb-specific changes in sEMG ARV, and activation timings reflected changes in joint angles and phasic shifts of the limb movement cycle following iFL and iHL. Muscular adaptations during iFL and iHL are detectable using sEMG and primarily involve increased bilateral activity and phasic activation shifts that reflect known compensatory movement patterns for reducing weightbearing on the lame limb. With further research and development, sEMG may provide a valuable diagnostic aid for quantifying the underlying neuromuscular adaptations to equine lameness, which are undetectable through human observation alone

Walking and trotting through a water track affects limb sagittal angles and stride timing in horses

Rehabilitation after musculoskeletal injury has become an essential part of veterinary care. Various forms of exercise in water have been described as an effective medium to improve function while preventing further injuries. This study evaluated kinematic changes of horses walking and trotting through a water track (WTr). Eleven Warmblood horses, equipped with IMU sensors (EquiMoves®; one on each leg) were measured overground (OG1), while going through a water track (85 m long; water height 33 cm), and once more overground (OG2). Linear mixed models were used to compare different conditions (

Computed tomographic features and surgical treatment of equine mandibular aneurysmal bone cysts with β-tricalcium phosphate in a multicenter case series

OBJECTIVE To describe clinical and imaging features and surgical treatment of equine mandibular aneurysmal bone cysts (ABCs) with β-tricalcium phosphate (TCP). ANIMALS 3 horses (cases 1, 2, and 3) and 1 pony (case 4) with histologically confirmed ABC. CLINICAL PRESENTATION All cases had mandibular swelling with intact adjacent skin. Cases 1 to 3 had a body condition score of 3/5 and case 4 had 2/5 and showed quidding during mastication and, at oral examination, large interdental spaces and loose elements adjacent to the swelling. Radiography or CT was performed in all cases. In cases 1, 3, and 4, an expansile septate cystic space-occupying lesion with mass effect on the adjacent cortices and teeth was seen without compact bone destruction. Case 2 showed a heterogeneous osteolytic mass with multifocal cortical lysis and interruption. Case 4 had severe dental abnormalities of deciduous and precursors of permanent teeth. ABCs were surgically treated and filled with only TCP (case 3) or in combination with autologous bone marrow (cases 1, 2, and 4). RESULTS Cases 1 through 3 showed an uneventful reduction in ABC size with increased opacity/attenuation. In case 4, a surgical site infection occurred. After removal of TCP remnants, the ABC healed satisfactorily, but remaining dental abnormalities necessitated dietary adjustments to maintain an acceptable body condition score. CLINICAL RELEVANCE Treatment of ABCs with TCP had a favorable outcome and good long-term prognosis. In young specimens, the expansile effect on the development and eruption of neighboring teeth can influence and determine final functionality of the diseased dental quadrant

Water and speed affect upper body kinematics and limb timing in horses walking on a water treadmill

This study aimed to describe upper body movement and limb timing in horses walking on a dry treadmill (DT) and water treadmill (WT) at incremental belt speeds. Upper body vertical range of motion (ROMz) and limb timing variables of twelve owner sound Warmblood horses were collected on a DT and WT. Water was set at the height of 30 cm and horses were measured at five different speeds (0.9-1.2 m/s) using ten IMU sensors (EquiMoves®, 200 Hz) attached to the head, withers, 15th thoracic vertebra, tuber sacrale, both tuber coxae and mid-lateral aspect of the cannon bones. Linear mixed models were used, with horses as random effect and the interaction of speed with treadmill condition (DT/WT) as fixed effects. Significance was set at

The effects of water and speed on limb kinematics in horses walking on a water treadmill

This study aimed to describe limb kinematics of horses walking on a dry treadmill (DT) and water treadmill (WT) at increasing belt speeds. Limb angle variables of twelve owner sound Warmblood horses were collected on a DT and WT (water height: 30 cm) at five different speeds (0.9-1.2 m/s), using four IMU sensors (EquiMoves®, 200 Hz) attached to the mid-lateral aspect of all metacarpal/metatarsal bones. Maximal front limb (FL) and hind limb (HL) protraction, retraction and sagittal range of motion (ROM) angles were calculated, as well as maximal FL and HL abduction, adduction and coronal ROM angles. Linear mixed-effects models were used to test the effects of water and speed. Significance was set at

Rater agreement for assessment of equine back mobility at walk and trot compared to quantitative gait analysis

Background Lameness assessment in horses is still predominantly performed using subjective methods. Visual assessment is known to have moderate to good intra-rater agreement but relatively poor inter-rater agreement. Little is known about inter- and intra-rater agreement on the evaluation of back motion, for which no objective measurement technique in a clinical setting is available thus far. Objectives To describe inter- and intra-rater agreement of visual evaluation of equine back mobility. Study design Rater reliability study using a fully crossed design in which all horses are rated by all observers. This data is compared with objective gait analysis. Methods Seventy equine professionals (veterinarians and physiotherapists) and veterinary students evaluated videos of 12 healthy horses at walk and trot on a hard, straight line. Nine parameters related to back mobility were scored: general mobility, thoracic, lumbar, lumbosacral flexion and extension and left and right thoracolumbar latero-flexion. All parameters were compared with simultaneously measured quantitative motion parameters. After 1 month, six randomly chosen horses were re-evaluated by 57 observers. Results For each parameter inter- and intra-rater agreements were calculated using intra-class correlation coefficients. For all parameters, inter-rater agreement was very poor (<0.2). The mean intra-rater agreement of all observers and for all parameters was poor (~0.4) but varied between 0.0 and 0.96 for individual observers. There was no correlation between the visual subjective scoring and objective gait analysis measurements. Main limitations Horses were scored from videos and by lack of any existing (semi-) quantitative system, a custom-made system had to be used. Conclusions The poor inter- and intra-rater agreements of visual scoring of mobility of the equine back and the disagreement between subjective and objective gait analysis data, demonstrate the need for the development and introduction of objective, quantitative and repeatable techniques to assess equine back motion

Electrode positioning in the horse: towards standardisation of surface EMG measurements

Surface electromyography (sEMG) is a well-established method in human gait analysis, and its application has extended towards the equine field in the past decades. However, methodological consensus regarding electrode positioning is lacking, resulting in different user methodologies, hampering study comparison and repeatability. This study investigated the standardisation of bipolar electrode positioning to measure muscle activity in horses during dynamic contractions. Ultrasound scans were made of three muscles (Triceps Brachii caput longum (TB), Longissimus Dorsi (LD), and Semitendinosus (ST)) of six horses to determine the muscle borders and fibre direction. Linear arrays of approximately ten electrodes (4 mm diameter, 20 mm inter-electrode distance) were placed on the clipped and cleaned skin, parallel to the muscle fibre direction. The middle of the array was always placed at 50% between two anatomical landmarks chosen near (one of ) the origins and insertions of the respective muscle. Data were collected (SAGA® TMSi, 4,000 Hz) for one minute at trot on a treadmill. The root mean square (RMS) values, innervation zone (IZ) location and presence of crosstalk were determined to evaluate electrode positions. The optimal positions were at 40-49 and 32-45% between the used anatomical landmarks for TB and ST respectively. Electrodes positioned within the thoracic region of the LD recorded higher, i.e. better, RMS values compared to electrodes in the lumbar region, though results were similar regarding IZ location and presence of crosstalk. The proposed positions may serve as a standardised reference for bipolar electrode placement to measure sEMG in horses during dynamic contractions.Effect of body position on a 3-dimensional scanning assessment of muscle massA. Borer-Matsui1, G.C. Donnelly2 and S. Valberg11Michigan State University, Large Animal Clinical Sciences, 736 Wilson Rd, 48824, East Lansing MI, USA, 2University of California, Davis, Department of Population Health and Reproduction, One Shields Drive, 95616, Davis CA, USA; [email protected] performance relies on well-developed musculature which has been difficult to accurately measure. We recently devised a 3-dimensional photonic scan to capture body volume (V) as a proxy for muscle mass validated in horses with 4 hooves square, a difficult stance to achieve. The purpose of this study was to determine the effect of modest differences in body position on measurement of body V. Anatomic markers were placed on 8 horses positioned with; 4 hooves square; neck turned ⌁25°; head raised mean 17 cm; one hind hoof (HH) anterior offset ⌁15 cm; a front and opposite HH ⌁15 cm offset (n=7); one HH resting. A handheld Occipital Structure Sensor scanner connected to an iPad and Skanect and Materialise 3-Matic programs were used to capture V in specific body sectors delineated by anatomic markers. Volume of back and hindquarter sectors standing square were compared to various positions using ANOVA (

A comparative study of breed differences in the anatomical configuration of the equine vertebral column

The importance of the equine thoracolumbar vertebral column in orthopaedic disorders is well recognized and diagnostic imaging becomes more feasible, but little is known about variations in the anatomical configuration within breeds. In this descriptive post-mortem study, anatomical variations in three widely differing breeds: Warmblood horses, Shetland ponies and semi-feral Konik horses are described. The caudal cervical (C), thoracic (T), lumbar (L) and sacral (S) regions of the vertebral column of 30 Warmblood horses, 29 Shetland ponies and 18 Konik horses were examined using computed tomography and visualized by volume rendering. Homologous/morphologic variations in the caudal cervical area were frequently seen in Warmblood horses (43%), which was significantly more than in the other breeds (p < 0.001). The as standard described equine formula of 18 T, 6 L and 5 S vertebrae was seen in 78% of Konik horses, but only in 53% Warmblood horses and 38% Shetland ponies, which was significantly different (p < 0.05). Overall, Shetland ponies showed a higher tendency of thoracoization, lumbarization and more variations in the number of vertebrae and pairs of ribs. Ankylosed intertransverse joints (ITJs) between transverse processes of the lumbar vertebrae were most common between the second last and last lumbar vertebra and prevalence was significantly higher in Shetland ponies (61%), than in Warmblood horses (38%) and Konik horses (7%) (p < 0.0001). Cranial to the second last lumbar vertebra there were fewer ITJs ankylosed (14%) in Warmblood horses (p < 0.0095), and this decrease in number of ankylosed ITJs was different compared to the change in ankylosed ITJs in Shetland ponies (p < 0.005). ITJs occurred asymmetrically in 15% (12/77) of the cases. A limitation of the study was that clinical data of the horses were only incompletely available, precluding any conclusions about the potential clinical implications of anatomical variations. Knowledge of variation in osseous anatomy of the equine thoracolumbar vertebral column is important for the interpretation of diagnostic imaging. To assess the functional importance and clinical relevance of this variation, follow-up studies are necessary