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Topic:Kinematics

Kinematics in horses refers to the study of motion without considering the forces that cause it. This field involves analyzing the movement patterns of horses, including gait, stride length, joint angles, and limb trajectories. Kinematic analysis is performed using technologies such as high-speed cameras and motion capture systems to collect data on equine locomotion. This information is valuable for understanding normal and abnormal movement, assessing performance, and identifying potential lameness or injury. The study of kinematics provides insights into the biomechanics of horse movement and contributes to advancements in training, rehabilitation, and veterinary care. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and applications of kinematic analysis in equine science.
Kinematics of the equine distal sesamoid (navicular) bone of the thoracic limb.
American journal of veterinary research    June 1, 2022   Volume 83, Issue 7 ajvr.21.07.0090 doi: 10.2460/ajvr.21.07.0090
Elane GL, Biedrzycki AH, McCarrel TM, Banks SA, Morton AJ.To quantify the translation and angular rotation of the distal sesamoid bone (DSB) using computed tomography (CT) and medical modeling software. Methods: 30 thoracic limbs from equine cadavers. Methods: Partial (n = 12), full (8), and matched full and subsequently transected (10) thoracic limbs were collected. Bone volume CT images were acquired in three positions: extension (200° metacarpophalangeal angle), neutral (180°), and maximal flexion (110°). Mean translation and angular rotation of each DSB were recorded. Differences were determined with two-way ANOVA and post hoc Tukey's tests fo...
Kinetic Analysis in Horses With Deep Digital Flexor Tendinopathy Within the Digit Diagnosed by Magnetic Resonance Imaging.
Frontiers in veterinary science    May 31, 2022   Volume 9 893026 doi: 10.3389/fvets.2022.893026
Madsen LM, Gutierrez-Nibeyro SD, Stewart MC, McCoy AM, Schaeffer DJ.To determine the stance duration and ground reaction forces (GRF) of horses with deep digital flexor (DDF) tendinopathy at the level of the foot and compare the stance duration and GRF to those of clinically sound horses. Unassigned: Prospective clinical study. Unassigned: Sixteen horses (seven horses with bilateral forelimb lameness, four horses with unilateral forelimb lameness, and five horses with no lameness). Unassigned: Analyses of kinetic variables were performed on both forelimbs from sound horses and horses diagnosed with chronic DDF tendinopathy. Stance duration and longitudinal and...
Determining Objective Parameters to Assess Gait Quality in Franches-Montagnes Horses for Ground Coverage and Over-Tracking – Part 1: At Walk.
Journal of equine veterinary science    May 29, 2022   Volume 115 104024 doi: 10.1016/j.jevs.2022.104024
Gmel AI, Haraldsdóttir EH, Serra Bragança FM, Cruz AM, Neuditschko M, Weishaupt MA.Ground coverage and over-tracking are two gait quality traits describing the forward movement of the front respectively the hind limbs in relation to stride length and over-tracking distance. To investigate the complex interplay of different movement patterns in ground coverage and over-tracking, limb and body kinematics of 24 Franches-Montagnes (FM) stallions were measured with 3D optical motion capture (OMC) on a treadmill during an incremental speed test at the walk (1.4-2.0 m/s). The significance and amount of explained variance of kinematic parameters on stride length and over-tracking di...
Effect of Water Depth on Limb and Back Kinematics in Horses Walking on a Water Treadmill.
Journal of equine veterinary science    May 29, 2022   Volume 115 104025 doi: 10.1016/j.jevs.2022.104025
Tranquille C, Tacey J, Walker V, Mackechnie-Guire R, Ellis J, Nankervis K, Newton R, Murray R.Water treadmill (WT) exercise is frequently used for training/rehabilitation of horses. There is limited study into the effect of water depth on limb/back kinematics warranting investigation. The objective was to determine the effect of walking in different water depths, at the same speed, on limb/back kinematics measured simultaneously in a group of horses. Six horses (age:15 ± 6.5 years) completed a standardized WT exercise session (19 minutes duration; speed:1.6 m/s; water depths: 0.0/7.5/21.0/32.0/47.0 cm). Ten waterproof light-emitting-diode tea-light-markers and reflective-spheres were ...
Effect of Ground and Raised Poles on Kinematics of the Walk.
Journal of equine veterinary science    May 6, 2022   Volume 115 104005 doi: 10.1016/j.jevs.2022.104005
Walker VA, Tranquillle CA, MacKechnie-Guire R, Spear J, Newton R, Murray RC.Walking over poles is a commonly employed training and rehabilitation tool and it is crucial to understand its effect on equine locomotion, particularly joint range of motion (ROM). The study aimed to compare the effect of ground poles (GP) and raised poles (RP) on limb kinematics and poll, wither and pelvic ROM at walk. It was hypothesized that walking over poles would increase joint ROM but have no effect on poll, wither and pelvic ROM compared to no poles (NP). Forty-one horses were walked in-hand over NP, GP (10 cm) and RP (26 cm) in a crossover design. Limb kinematics were determine...
Morphine with or without Acepromazine in Horses: A Kinematic Evaluation.
Animals : an open access journal from MDPI    May 6, 2022   Volume 12, Issue 9 1193 doi: 10.3390/ani12091193
López-Sanromán FJ, Montes Freilich G, Gómez-Cisneros D, Izquierdo-Moreno J, Varela Del Arco M, Manso-Díaz G.The objective was to demonstrate walking locomotor pattern alterations after co-administration of acepromazine and morphine in horses. Six mature horses receiving four different treatments were used. Treatments consisted of a single dose of saline solution, 0.2 mg/kg bwt of morphine hydrochloride, 0.02 mg/kg bwt of acepromazine maleate, and a combination of 0.2 mg/kg bwt of morphine hydrochloride with 0.02 mg/kg bwt of acepromazine maleate. A three-dimensional accelerometric device was used to collect data. Walking tests were performed 10 min prior to injection, and then at 5, 10, 15, and 20 m...
Modelling fore- and hindlimb peak vertical force differences in trotting horses using upper body kinematic asymmetry variables.
Journal of biomechanics    April 15, 2022   Volume 137 111097 doi: 10.1016/j.jbiomech.2022.111097
Roepstorff C, Imogen Gmel A, Arpagaus S, Manuel Serra Bragança F, Hernlund E, Roepstorff L, Rhodin M, Andreas Weishaupt M.Differences in peak vertical ground reaction forces (dFz) between contralateral forelimbs and hindlimbs are considered the gold standard for quantifying weight-bearing lameness. However, measuring kinematics for the same purpose is more common and practical. Vertical movement asymmetries (VMA) of the horse's upper body have previously been correlated to fore- and hindlimb lameness. But the combined response of head, withers and pelvis VMA to fore- and hindlimb dFz has not yet been thoroughly investigated. Deriving the kinetic responses from kinematics would help the interpretation and understa...
Three-Dimensional Modeling and In Silico Kinematic Evaluation of Interspinous Ligament Desmotomy in Horses.
Frontiers in bioengineering and biotechnology    April 1, 2022   Volume 10 817300 doi: 10.3389/fbioe.2022.817300
Biedrzycki AH, Elane GL. Interspinous ligament desmotomy (ISLD) has been shown to improve the comfort of horses diagnosed with overriding dorsal spinous processes (DSP), but its effects on spine mobility are unknown. To objectively quantify the change in mobility of thoracic vertebrae following ISLD using CT and medical modeling software. Prospective cadaveric manipulation of seven equine thoracolumbar spines collected from T11-L1. Spines were collected from T11-L1 with the musculature intact. Flexion and extension phases were achieved with a ratchet device calibrated to 2000N. Bone volume CT scans were performed ...
Evaluating the Effect of Routine Hoof Trimming on Fore and Hind Hooves Impact Phase Kinetics.
Journal of equine veterinary science    March 18, 2022   Volume 114 103935 doi: 10.1016/j.jevs.2022.103935
Faramarzi B, Nelson S, Dong F.Imbalances and altered kinetics of the hoof result in lameness in horses. Previously, studies have focused on the midstance phase of a gait, hence, available information on the impact phase is scarce. This study aimed to investigate the effect of hoof trimming on the fore and hindhooves at the impact phase of the walk. Our objective was to compare the kinetic variables of force (N), contact area (cm), contact pressure (kPa), and peak contact pressure (kPa) before and after hoof trimming. Nine Arabian horses were walked straight over a pressure plate to collect the above kinetic variables for b...
Linear Discriminant Analysis for Investigating Differences in Upper Body Movement Symmetry in Horses before/after Diagnostic Analgesia in Relation to Expert Judgement.
Animals : an open access journal from MDPI    March 17, 2022   Volume 12, Issue 6 doi: 10.3390/ani12060762
Pfau T, Bolt DM, Fiske-Jackson A, Gerdes C, Hoenecke K, Lynch L, Perrier M, Smith RKW.Diagnostic analgesia and lunging are parts of the equine lameness examination, aiding veterinarians in localizing the anatomical region(s) causing pain-related movement deficits. Expectation bias of visual assessment and complex movement asymmetry changes in lame horses on the lunge highlight the need to investigate data-driven approaches for optimally integrating quantitative gait data into veterinary decision-making to remove bias. A retrospective analysis was conducted with inertial sensor movement symmetry data before/after diagnostic analgesia relative to subjective judgement of efficacy ...
A Scoping Review of Equine Biomechanics Revisited.
Journal of equine veterinary science    March 4, 2022   Volume 113 103920 doi: 10.1016/j.jevs.2022.103920
Egenvall A, Byström A, Lindsten A, Clayton HM.As techniques for equine biomechanical research have become more accessible and affordable, the literature published in this area has exploded. Literature reviews have become more popular of late and, more specifically, several literature reviews in areas related to equine biomechanics have been published. A scoping review is a relatively new approach, where a general aim is to map the body of literature on a topic area, accounting for criteria for inclusion and exclusion. However, problems can arise both in performing the review and in critiquing the findings. In this manuscript, the authors ...
Center of Mass Offset Enhances the Selection of Transverse Gallop in High-Speed Running by Horses: A Modeling Study.
Frontiers in bioengineering and biotechnology    February 28, 2022   Volume 10 825157 doi: 10.3389/fbioe.2022.825157
Yamada T, Aoi S, Adachi M, Kamimura T, Higurashi Y, Wada N, Tsuchiya K, Matsuno F.Horses use the transverse gallop in high-speed running. However, different animals use different gaits, and the gait preference of horses remains largely unclear. Horses have fore-aft asymmetry in their body structure and their center of mass (CoM) is anteriorly located far from the center of the body. Since such a CoM offset affects the running dynamics, we hypothesize that the CoM offset of horses is important in gait selection. In order to verify our hypothesis and clarify the gait selection mechanisms by horses from a dynamic viewpoint, we developed a simple model with CoM offset and inves...
Upper Body Movement Symmetry in Reining Quarter Horses during Trot In-Hand, on the Lunge and during Ridden Exercise.
Animals : an open access journal from MDPI    February 27, 2022   Volume 12, Issue 5 doi: 10.3390/ani12050596
Pfau T, Scott WM, Sternberg Allen T.Veterinary lameness examinations often comprise assessing ridden horses. Quantitative movement symmetry measurements can aid evidence-based decision making. While these are available for ‘English’ style riding, they are not for ‘Western’ style riding. This quantitative observational study quantified movement symmetry in reining Quarter Horses (QHs). Movement symmetry of the head, withers and sacrum (differences between minima, maxima and upward amplitudes) were quantified with inertial sensors in N = 30 medium/high level reining QHs during trot in-hand, on the lunge and ridden by one e...
Response of the Thoroughbred Forelimb to Perturbations Caused by a Change in Ground Surface.
Journal of equine veterinary science    February 10, 2022   Volume 112 103897 doi: 10.1016/j.jevs.2022.103897
Bardin AL, Taylor NC, Robert Colborne G.Thoroughbred racehorses are often affected by musculoskeletal injuries, leading to involuntary rest, early retirement or death. Hardness and consistency of the track surface have been implicated as major risk factors for limb injury. The purpose was to test the utility of a preliminary AnyBody musculoskeletal model of the equine forelimb for its responses on two perturbing surfaces. A musculoskeletal model was developed using CT, muscle, tendon and ligament properties, and kinematic data were applied from ridden trials using five Thoroughbred horses. Horses were ridden at trot and canter on a ...
Influence of 8-Week Horseback Riding Activity on Balance and Pelvic Movements in an Older Adult Population.
Journal of aging and physical activity    February 7, 2022   Volume 30, Issue 5 906-915 doi: 10.1123/japa.2021-0237
Severyn AMH, Luzum NR, Vernon KL, Van Puymbroeck M, DesJardins JD.The biomechanical relationship between horse and rider in equine-assisted activities and therapies has been largely unexplored. The three-dimensional stimulation of the horse's gait has potential to improve rider musculature and coordination, especially in an older adult population. This study utilized dual-axis goniometers and video motion capture tracking to simultaneously track horse and rider hip flexion and extension. Ten older adult riders participated in 8 weeks of horseback riding lessons, where pelvis kinematics and balance assessments were compared between Weeks 1 and 8. Pelvic roll ...
Kinematic Analysis During Straight Line Free Swimming in Horses: Part 2 – Hindlimbs.
Frontiers in veterinary science    January 31, 2022   Volume 8 761500 doi: 10.3389/fvets.2021.761500
Santosuosso E, Leguillette R, Vinardell T, Filho S, Massie S, McCrae P, Johnson S, Rolian C, David F.Swimming is used for rehabilitation and conditioning purposes in equine sports medicine. We described the swimming kinematics of the equine forelimbs in Part 1. The aim of Part 2 is to assess stifle, tarsus, and hind fetlock joints kinematics in swimming horses. The objectives were 1- to calculate and compare joint angles during swimming against passive mobilizations (PM), 2- to determine joints angular velocities during a swimming stride cycle. Methods: Eleven elite endurance horses were used to swim in a 100-meter straight pool. Underwater (swimming) and overground PM videos were recorded fr...
Effects of a Bio-Electromagnetic Energy Regulation Blanket on Thoracolumbar Epaxial Muscle Pain in Horses.
Journal of equine veterinary science    January 23, 2022   Volume 111 103867 doi: 10.1016/j.jevs.2022.103867
King MR, Seabaugh KA, Frisbie DD.Back pain and inflammation of the epaxial musculature is a significant problem in all equine athletes. Treatment of back pain can be challenging and often requires a multimodal approach. In humans, bio-electromagnetic energy regulation therapy (BEMER) has been reported to be effective in pain modulation. With its increased use in people comes a similar robust application in veterinary medicine unfortunately, there is unsubstantiated evidence for this type of therapy in horses. Objectives of this study were to assess analgesic responses and biomechanical outcome variables using a bio-electromag...
The Effects of the EquiAmiTM Training Aid on the Kinematics of the Horse at the Walk and Trot In-Hand.
Journal of equine veterinary science    January 22, 2022   Volume 111 103868 doi: 10.1016/j.jevs.2022.103868
Calzone S, Wilkins C, Deckers I, Nankervis K.The EquiAmi Training Aid (ETA) is a popular training and rehabilitation tool, however knowledge about its effect on the equine gait is lacking. Understanding of its effects on equine kinematics, and the clinical relevance of these effects is vital to promote optimal use of training aids within training and rehabilitation programmes. Therefore, this study aimed to determine how the ETA influences horses' gait kinematics at walk and trot. Eight horses walked and trotted in-hand with and without the ETA. Optical motion capture was used to measure forelimb and hindlimb pro- and retraction angles, ...
Visual lameness assessment in comparison to quantitative gait analysis data in horses.
Equine veterinary journal    January 10, 2022   Volume 54, Issue 6 1076-1085 doi: 10.1111/evj.13545
Hardeman AM, Egenvall A, Serra Bragança FM, Swagemakers JH, Koene MHW, Roepstorff L, van Weeren R, Byström A.Quantitative gait analysis offers objective information to support clinical decision-making during lameness workups including advantages in terms of documentation, communication, education, and avoidance of expectation bias. Nevertheless, hardly any data exist comparing outcome of subjective scoring with the output of objective gait analysis systems. Objective: To investigate between- and within-veterinarian agreement on primary lame limb and lameness grade, and to determine relationships between subjective lameness grade and quantitative data, focusing on differences between (1) veterinarians...
Impact of Gait and Diameter during Circular Exercise on Front Hoof Area, Vertical Force, and Pressure in Mature Horses.
Animals : an open access journal from MDPI    December 17, 2021   Volume 11, Issue 12 doi: 10.3390/ani11123581
Logan AA, Nielsen BD, Robison CI, Hallock DB, Manfredi JM, Hiney KM, Buskirk DD, Popovich JM.Circular exercise can be used at varying gaits and diameters to exercise horses, with repeated use anecdotally relating to increased lameness. This work sought to characterize mean area, mean vertical force, and mean pressure of the front hooves while exercising in a straight line at the walk and trot, and small (10-m diameter) and large circles (15-m diameter) at the walk, trot, and canter. Nine mature horses wore TekscanTM Hoof Sensors on their forelimbs adhered with a glue-on shoe. Statistical analysis was performed in SAS 9.4 with fixed effects of leg, gait, and exercise type (PROC GLIMMIX...
The effect of horseshoes and surfaces on horse and jockey centre of mass displacements at gallop.
PloS one    November 23, 2021   Volume 16, Issue 11 e0257820 doi: 10.1371/journal.pone.0257820
Horan K, Kourdache K, Coburn J, Day P, Carnall H, Harborne D, Brinkley L, Hammond L, Millard S, Lancaster B, Pfau T.Horseshoes influence how horses' hooves interact with different ground surfaces, during the impact, loading and push-off phases of a stride cycle. Consequently, they impact on the biomechanics of horses' proximal limb segments and upper body. By implication, different shoe and surface combinations could drive changes in the magnitude and stability of movement patterns in horse-jockey dyads. This study aimed to quantify centre of mass (COM) displacements in horse-jockey dyads galloping on turf and artificial tracks in four shoeing conditions: 1) aluminium; 2) barefoot; 3) GluShu; and 4) steel. ...
Rider Skill Affects Time and Frequency Domain Postural Variables When Performing Shoulder-in.
Journal of equine veterinary science    November 6, 2021   Volume 109 103805 doi: 10.1016/j.jevs.2021.103805
Baxter J, Hobbs SJ, Alexander J, George LS, Sinclair J, Chohan A, Clayton HM.In equestrian sports the novice rider learns first to follow the movements of the horse's back and then how to influence the horse's performance. One of the rider's challenges is to overcome inherent horse and/or rider asymmetry patterns when riding in straight lines, mirroring the movements on the left, and right sides when turning. This study compares the performance of novice and advanced riders when riding in sitting trot on straight lines and when riding shoulder-in to the left and right sides. Eight novice and eight advanced horse-rider combinations performed sitting trot in a straight l...
Roll And Pitch of the Rider’s Pelvis During Horseback Riding at Walk on a Circle.
Journal of equine veterinary science    October 29, 2021   Volume 109 103798 doi: 10.1016/j.jevs.2021.103798
Egenvall A, Clayton H, Engell MT, Roepstorff C, Engström H, Byström A.The study investigated between-rider differences in pelvic roll and pitch motion during horseback riding as the horse walked around circles without rein contact (walk on long reins), with rein contact, and with moderate collection. Ten horses were ridden by five riders on left and right 10 m circles, in a partly crossed design, yielding 14 trials. Each trial included each of the three walk variations in both directions. Riders wore an inertial measurement unit (IMU), logging at 100 Hz, dorsally on the pelvis. Pelvic roll and pitch data were split into strides based on data from IMU-sensors on ...
Kinematic Analysis During Straight Line Free Swimming in Horses: Part 1 – Forelimbs.
Frontiers in veterinary science    October 14, 2021   Volume 8 752375 doi: 10.3389/fvets.2021.752375
Santosuosso E, Leguillette R, Vinardell T, Filho S, Massie S, McCrae P, Johnson S, Rolian C, David F.Background: Swimming is used for rehabilitation and conditioning purposes in equine sports medicine despite the lack of understanding of equine swimming kinematics. The aim of this study was to assess forelimb joints kinematics (elbow, carpus, and fetlock) in swimming horses. The specific objectives were 1- to calculate and compare joint angles in swimming vs. passive mobilizations (PM), 2- to determine joint angular velocities during a swimming stride cycle. Methods: Eleven elite endurance horses swam in a 100-m straight pool. Underwater (swimming) and overground (PM) videos were recorded fro...
Kinematic Patterns in Horses Sedated With Low Doses of Detomidine: An Accelerometric Evaluation.
Journal of equine veterinary science    October 2, 2021   Volume 107 103777 doi: 10.1016/j.jevs.2021.103777
Calvo-Santesmases A, Manso-Díaz G, Fores P, López-Sanromán J.Alpha-2-adrenergic drugs, such as detomidine, are commonly used to sedate lame horses during examination. However, the use of these drugs should be minimized, as they have numerous side-effects, like ataxia. Therefore, we wanted to test the effects, on the locomotor pattern, of low doses of detomidine (0.003 mg/kg). Six horses were sedated with 0.003 mg/kg of detomidine and compared with the same horses administered a saline solution. Using a triaxial accelerometer, data of kinetic, coordination and energetic locomotor parameters and the degree of sedation were collected. The effects were moni...
Equine spinal kinematics derived from different riding positions during asymmetrical bareback riding.
Journal of equine science    September 6, 2021   Volume 32, Issue 3 81-89 doi: 10.1294/jes.32.81
Nuchprayoon N, Ritruechai P, Watchararat K, Limroongruengrat W, Wongtawan T, Arya N.Hippotherapy in patients with neuromuscular dysfunction creates high focal pressure on the pony's back due to bareback riding and an asymmetrical riding position. This study aimed to investigate the acute effect of asymmetrical bareback riding on the pony's spinal kinematics, blood lactate, serum creatine kinase, heart rate, and temperament score. Eight ponies were selected, and they were walked on a treadmill for 45 min on each experimental day, including warm-up (5 min), weight-loading by mannequin (30 min), and cool-down (10 min) sessions. During the weight-loading session, three different ...
Physical therapy treatments incorporating equine movement: a pilot study exploring interactions between children with cerebral palsy and the horse.
Journal of neuroengineering and rehabilitation    September 6, 2021   Volume 18, Issue 1 132 doi: 10.1186/s12984-021-00929-w
Lightsey P, Lee Y, Krenek N, Hur P.Physical therapy treatments incorporating equine movement are recognized as an effective tool to treat functional mobility and balance in children with cerebral palsy (CP). To date, only a few studies examined kinematic outputs of the horses and children when mounted. In this pilot study, to better understand the effectiveness of this type of treatment, we examined the interaction between the horses and children with CP during physical therapy sessions where equine movement was utilized. Four children with CP participated in eight physical therapy sessions incorporating hippotherapy as a treat...
The influence of equine limb conformation on the biomechanical responses of the hoof: An in vivo and finite element study.
Journal of biomechanics    August 28, 2021   Volume 128 110715 doi: 10.1016/j.jbiomech.2021.110715
Akbari Shahkhosravi N, C R Bellenzani M, M S Davies H, Komeili A.Hoof conformation plays a key role in equine locomotion. Toe-in conformation is an abnormal condition characterized by inward deviation of the limb from its frontal axis. Several studies have documented differences in hoof deformation and hoof kinematics in horses with toe-in and normal hoof conformations. However, the reason behind this has yet to be understood. The present study hypothesizes that a different center of pressure (COP) path underneath the hoof is the cause of different deformation patterns and hoof kinematics in toe-in hooves. In vivo measurements and finite element (FE) analys...
3D kinematic of the thoracolumbar spine in Mangalarga Marchador horses performing the marcha batida gait and being led by hand-A preliminary report.
PloS one    July 6, 2021   Volume 16, Issue 7 e0253697 doi: 10.1371/journal.pone.0253697
Simonato SP, Bernardina GRD, Ferreira LCR, Silvatti AP, Barcelos KMC, da Fonseca BPA.This study aimed to provide a preliminary description of the sagittal and transverse plane kinematics of the thoracolumbar spine of Mangalarga Marchador (MM) horses performing the marcha batida gait, led in-hand. We evaluated the pattern of angular movement and the mean amplitude of six specific angles. An optoelectronic system was used for 3D kinematic analysis (19 cameras, 250 Hz). They were positioned around the horses and an acquisition volume of 16 × 4.8 × 3 meters was used. Eight retroreflective markers were fixed on the spine of the animals over thoracic vertebrae 8 (T8), 12 (T12), 15...
Accelerometric Evaluation of the Locomotor Pattern After Administration of Morphine in Conscious Healthy Horses.
Journal of equine veterinary science    July 2, 2021   Volume 104 103701 doi: 10.1016/j.jevs.2021.103701
López-Sanromán FJ, Freilich GM, Gomez-Cisneros D, Varela M, Santiago I, Manso-Díaz G.The objective of the present study was to compare, using accelerometry, the gait changes produced after administration of a dose of 0.2 mg/kg of morphine at the walk in healthy horses. Six mature horses were used, and all animals received two different treatments with, at least, two weeks interval in between. Treatments administered consisted of a single dose of 10 ml of saline solution or a total of 0.2 mg/kg of morphine diluted in 10 ml of saline solution. A three-dimensional accelerometric device was used to collect data continuously while horses were walking. The walking test was performed...