The musculoskeletal system in horses encompasses the bones, muscles, tendons, ligaments, and joints that facilitate movement and provide structural support. This system is essential for locomotion, athletic performance, and overall health in equine species. The equine skeleton consists of approximately 205 bones, which are connected by joints and supported by a network of muscles and connective tissues. Tendons connect muscles to bones, while ligaments link bones to other bones, contributing to joint stability. The musculoskeletal system is subject to various conditions, including injuries, degenerative diseases, and developmental disorders, which can impact a horse's mobility and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, pathology, and treatment of musculoskeletal conditions in horses.
Turner AS, Mills EJ, Gabel AA.Strain gauges were successfully bonded in vivo to the cranial, caudal, medial, and lateral aspects of the equine radium and tibia and to the dorsal, palmar, or plantar, medial, the lateral aspects of the metacarpus and metatarsus--all in the mid-diaphyseal region. Various activities were investigated, including walking, trotting or pacing, and standing up from anesthesia. The strain patterns showed that each stride produced a characteristic deformation cycle. The strains were measured and the axial loads were calculated as the horse performed certain activities. The tension band side of each b...
White NA, Wheat JD.Proximal tibial epiphyseal fractures in 2 foals were reduced and stabilized by expansion and compression between 2 transversely placed Steinman pins, one on each side of the fracture. A Charnley apparatus or turnbuckles placed between the pins on each side of the fracture provided the mechanical advantage for repositioning the fracture fragments and achieving rigid fixation during healing. A light cast was applied over the fixation apparatus, keeping the limb in an extended position. The cast and fixation apparatus were removed after 4 weeks. The technique allowed rapid healing and adequate am...
Irvine CH, Evans MJ.Total tyhroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3) and free triiodothyronine (FT3) concentrations in foal umbilical cord blood were respectively 14, 5 7 and 3 times the concentrations of these hormones in adult horse blood. The TT4 levels in foals declined rapidly to reach adult concentrations by Day 16 and FT4 levels declined steadily during the first 3 months of life. Foal TT3 levels rose during the first 10 hr after birth and thereafter declined, although they were still X2-5 higher than adult levels at 3 months of age. Levels of FT3 similarly increased after birth be...
McMahon TA.Many parameters of gait and performance, including stride frequency, stride length, maximum speed, and rate of O2 uptake are experimentally found to be power-law functions of body weight in running quadrupeds. All of these parameters are reasonably easy to measure except maximum speed, where the question arises whether one means top sprinting speed or top speed for sustained running. Moreover, differences in training and motivation make comparisons of top speed difficult. The problem is circumvented by comparing animals running at the transition between trotting and galloping, a physiologicall...
Sack WO.The nerve distribution to the digit of the horse was studied with the compound microscope in serial transverse sections of fetal limbs and plotted on life-size outlines of the horse's foot. It was learned that there is much variation in the topography of the branches of the principal nerves. There is no mirror-image nerve distribution on the 2 sides of the foot. The dorsal branch of the ulnar nerve does not extend below the fetlock. The communication between the palmar metacarpal nerves and branches of the dorsal branch of the digital nerves is only a crossing of nerves without exchange of fib...
Takeuchi K, Shibata N, Senda N.Myosin was isolated from leucocytes in horse arterial blood by the same procedures used for the isolation of myosin from skeletal muscle. The Ca2+-, EDTA-, and Mg2+-ATPase [EC 3.6.1.3] activities of the protein was 0.148, 0.147, and 0.001 mumoles/min/mg, respectively, in 0.5 M KCl at pH 7.0 and 25 degrees. The Ca2+-ATPase activity decreased with decrease in the ionic strength. No difference was found between leucocyte myosin and skeletal myosin in the pH profiles of Ca2+- and EDTA-ATPases. The rate and amount of the initial burst of Pi liberation of leucocyte myosin were 0.002 mumoles/min/mg a...
Jeffcott LB, Hickman J.This paper describes the surgical treatment of 14 horses exhibiting chronic back pain attributed to impaction and overriding of the dorsal spines in the thoracolumbar region. The technique involved the resection of the summits of one or more dorsal spines following midline division of the supraspinous ligament. All the horses returned to full work after a convalescent period of at least four months, and 12 of them showed considerable improvement in their form and performance. A post-surgical complication encountered in one case was the development of new bone on the edge of a resected spine. T...
Menschik A.Mobility of the knee of the horse. The modification of medial and lateral femoral condyles by additional movement of the cruciate ligaments shown on the animal joint. Final rotation in the human knee-joint shapes the femoral condyles by additional movement of the cruciate ligaments. The roll-slide movement and final rotation lead to curving of the medial condyle of the femur in the transverse plane. The transition from the roll-slide into a tilting movement in the final phase of ultimate rotation reduces the power of the posterior ligamentous system of the knee-joint when there is a force tend...
Hördegen KM.115 horseback riders have undergone clinical and radiologic examinations of the spine. A minimum of 10 years' riding was required. Depending on intensity of training and number of riding hours, the subjects were divided into three groups: roughriders, sport riders and hobby riders. It was striking that of the bare half of cases (51) suffering from lower back, only 8 (about 15%) had had medical treatment and actually been disabled. Moreover, 47% of the riders with lower back pain were painfree in the saddle, i.e. when riding. No causal connection was found between riding and a higher incidence ...
Brown MP, MacCallum FJ.Tetracycline-labeled bones of 23 foals from 52 to 104 days old were sectioned and macroscopically examined to assess the extent of ossification or fusion of ossification centers. A grading system was devised with which to record information about the ossification centers and growth plates. The objective was to define anatomic standards which could contribute toward obtaining an accurate radiologic interpretation. Labeled limb bones of 3 neonatal foals were similarly treated, but grading of these was limited to the consideration of whether each site was still cartilaginous or had commenced to o...
Crowhurst RC.Diseases of the back of horse and man are not comparable owing to the great difference in anatomy and posture. Veterinary surgeons, particularly in the United Kingdom, are often requested to account for a poor performance due to suspected "back trouble" but a complete examination of the horse's back is most difficult and care must be taken first to exclude any limb or foot lesions. Diseases of the bones, nerves and muscles are briefly discussed. Diagnosis must be improved by new radiographic and biochemical tests before the significance of back lesions can be assessed or even treated.
Beckett SD, Walker DF, Hudson RS, Reynolds TM, Purohit RC.A needle-tipped catheter or subminiature pressure transducer was implanted in the corpus spongiosum penis (CSP) of Shetland Pony stallions to determine pressure during coitus. Electrodes for monitoring the electromyographic (EMG) activity were implanted in the ischiocavernosus (IC) and bulbospongiosus (BS) muscles. The mean peak CSP pressure recorded with the catheter was 762 mm of Hg, and with the subminiature pressure transducer, it was 994 mm of Hg. The simultaneous occurrence of the CSP pressure peaks and bursts of BS muscle activity indicated that these muscles were the likely source of e...
Jeffcott LB.A description of some of the clinical features of low back pain in the horse has been given and a number of methods for assisting diagnosis considered. As well as a complete clinical examination both at rest and during exercise, a useful diagnostic aid in some chronic cases was the injection of local anaesthetic into the interspinous spaces. A laboratory examination, including haematological and biochemical profiles, was undertaken in all cases. The serum enzymes GOT and CPK were particularly valuable as an aid to diagnosis in atypical tying-up. A technique for radiography of the vertebral col...
Frei S, Fürst AE, Sacks M, Bischofberger AS.Three horses that were presented with supraglenoid tubercle fractures were treated with open reduction and internal fixation using distal femoral locking plates (DFLP). Placing the DFLP caudal to the scapular spine in order to preserve the suprascapular nerve led to a stable fixation, however, it resulted in infraspinatus muscle atrophy and mild scapulohumeral joint instability (case 1). Placing the DFLP cranial to the scapular spine and under the suprascapular nerve resulted in a stable fixation, however, it resulted in severe atrophy of the supraspinatus and infraspinatus muscles and scapulo...
Peli A, Roccaro M.Catastrophic injuries in racehorses mostly involve the metacarpal region. Although many studies describe fractures of equine limbs, few examine the relationship between bone morphometrics and musculoskeletal problems in racing horses. And yet, according to the regulation of some Italian traditional races, the shin circumference represents a qualifying prerequisite for horses to be admitted to races. This study aims to evaluate the conformity of the shin circumference measurement in living animals and in post‑mortem examinations, in order to evaluate the forensic reliability of these measurem...
Leach DH, Crawford WH.This paper describes the major areas that require investigation in equine locomotion and outlines a plan for such research in both the Thoroughbred and Standardbred. Fifteen topics for future investigation have been selected and given an order of priority. These topics deal with characteristics of normal locomotion, factors which influence locomotion, the epidemiology and economics of lameness and the clinical identification of lameness.
Szalay F, Back W, Barneveld A, Schamhardt H, Hajós F.A VHS video--computer-based image analysis combination is described as a low sampling rate motion analysis system. Video recordings were taken indoor without any artificial illumination at 25 fps sampling rate. The horse studied was running on a high-speed treadmill and observed at 1.6, 4 and 7 m/s velocities at walk, trot and canter, respectively. Left forelimb and hindlimb were recorded separately from lateral view. For comparison, parallel CODA-3 recordings were taken at the same time from the same position. Joint angles were expressed and compared in angle-time diagrams. Sampling of both s...
Sha DH, Mullineaux DR, Clayton HM.Surface markers are usually used to track bone movement. However, skin movement related to the bone has a large effect on the analysis of skeletal kinematics. A 2-dimensional (2D) skin displacement correction model has been successfully developed, but no 3D skin displacement model exists. Objective: To develop a 3-dimensional (3D) skin displacement model for the equine radial segment during trot. Methods: The 3D trajectories of 6 skin-based markers and a bone-fixed triad were captured at trot in 4 horses. Skin displacements in the bone-based coordinate system were calculated using a singular-v...
Giacchi A, McMaster MA.To compare biomechanical characteristics of three-loop pulley (3LP) pattern versus Bunnell technique (BT) using polydioxanone (PDS) suture; to determine the influence of polyester tape (PT) versus PDS on the BT for equine superficial digital flexor tendon (SDFT) tenorrhaphy; to compare BT with PT versus 3LP with PDS. Methods: Ex vivo biomechanical study. Methods: Forty equine forelimb SDFT. Methods: Two experiments were performed: (1) 10 SDFT pairs were repaired with 3LP or BT using PDS; (2) 10 SDFT pairs were repaired with PDS or PT using BT. Load at failure, mode of failure, load at 2 mm g...
Yudkowsky ML, Beech J, Fletcher JE.In equine hyperkalemic periodic paralysis (HyperPP), there is evidence suggesting that the primary defect in the sodium channel is associated with a secondary alteration in triacylglycerol-associated fatty acid metabolism (TAFAM) in skeletal muscle. Furthermore, TAFAM may be involved in the therapeutic action of phenytoin. The effects of phenytoin treatment on the transcript levels of three key proteins in TAFAM, hormone sensitive lipase (HSL), carnitine palmitoyltransferase (CPT), and fatty acid binding protein (FABP), were examined. These transcripts were quantitated by competitive reverse t...
White NA.Transection of the accessory ligament of the deep digital flexor muscle (distal check ligament desmotomy) was completed in 44 horses using an ultrasound-guided technique. The technique used real-time ultrasound with a 7.5 MHz transducer to observe the dissection and isolation of the check ligament through a 1 to 1.5 cm incision and to check for complete transection of the check ligament. The technique was effective in correcting flexural deformity of the distal interphalangeal joint and the metacarpophalangeal joint in all but three horses. Check ligament desmotomy at a young age (median, 6 mo...
Tucker RL, Schneider RK, Sondhof AH, Ragle CA, Tyler JW.Nuclear bone scintigraphy was used to diagnose sacroiliac injury in 12 horses presented for nonspecific rear limb lameness. The most common history was decreased performance and/or a mild chronic rear limb lameness which could not be localised by routine lameness examination. The scintigraphic patterns of the 12 affected horses were compared to 5 normal horses and 10 horses with lameness not related to the pelvic region. Subjective and quantitative evaluation of the bone scans clearly separated the 12 affected horses from the 5 normal horses and the 10 horses with lameness from causes other th...
Fletcher JE, Erwin K, Beech J.Previous studies have demonstrated that phenytoin decreases the levels of triacylglycerols in several tissues other than skeletal muscle. Since phenytoin is clinically effective in several skeletal muscle disorders, triacylglycerol metabolism in skeletal muscle from four normal Quarter horses and four Quarter horses with hyperkalemic periodic paralysis was examined. The horses with hyperkalemic periodic paralysis had low levels of 18:3 in the phospholipids, low levels of 16:0, 16:1 and 18:3 in the free fatty acids and low levels of 20:4 in triacylglycerols. Triacylglycerol levels were increase...
Walmsley EA, Anderson GA, Adkins AR.Determine the long-term outcome for Thoroughbreds undergoing desmotomy of the accessory ligament of the deep digital flexor tendon (DAL-DDFT) for type 1 flexural deformity of the distal interphalangeal joint (DIPJ). Methods: Retrospective matched cohort study Methods: Medical records were retrieved over a 17-year period for Thoroughbreds that underwent DAL-DDFT for type 1 flexural deformity. Long-term outcome was determined by analysis of race records and comparison with maternal siblings. Comparisons between cases and controls included 2-year-old, 3-year-old and total career performance data....
May-Davis S, Doveren A, Sweere R, Smak J, Vermeulen Z.Hereditary multiple exostoses (HME) is a condition rarely diagnosed in horses, which has not been previously reported in Dutch Warmblood horses. Its presentation resembles that diagnosed in humans, and it is predominantly active during periods of skeletal maturation. This case study reports a link between a granddam with no obvious HME lesions and its first and second generations presenting with HME, albeit with different sires. The severity in affected horses (n = 5) varied from one foreleg to the other with extensive multiple lesions of 123 of 205 bones in a half sibling in the first genera...
King N, Suleiman MS.Exercise induces significant changes in the free intracellular amino acid pool in skeletal muscle but little is known of whether such changes also occur in cardiac muscle. In this study the effect of regular exercise on the size and the constituents of the free amino acid pool in the hearts and in the plasma of thoroughbred horses was investigated. The total free intracellular amino acid pool in the hearts of control horses was 30.9 +/- 1.2 mumol/g wet weight (n = 6). Glutamine but not taurine was present at the highest concentration (13.5 +/- 0.9 and 7.7 +/- 0.69 mumol/g wet weight for glutam...
Ludwig EK, Hallowell K, Womble M, O'Neil E.A 2-day-old Cleveland Bay colt was referred to the Equine Emergency Service of the Farm Animal and Equine Veterinary Medical Center at North Carolina State University's College of Veterinary Medicine for evaluation of decreased nursing behaviour and right hindlimb lameness of 2 days' duration. When assisted to stand, the foal was unable to extend either hindlimb or bear weight on the hindlimbs, the right patella was luxated laterally and unable to be reduced, and the foal assumed a crouched position. Stifle radiographs revealed minimal, heterogeneous, ill-defined ossification of both patellae....
Hauspie S, Martens A, Declercq J, Busoni V, Vanderperren K, van Bree H, Saunders JH.To describe the radiographic appearance of the dorsoproximal aspect of the sagittal ridge of the third metacarpal/metatarsal bone in Warmblood horses. Methods: The lateromedial radiographic projections of the metacarpo-/metatarsophalangeal joints performed on horses as a part of stallion selection were used. The dorsal aspect of the distal third metacarpal/metatarsal bone was divided in two areas. The appearance of the bone surface in area I was classified as normal, irregular, notch, indentation and lucency. For area II, the categories were normal, irregular, depression or lucency and flatten...
Kirker-Head CA, Kerwin PJ, Steckel RR, Rubin CT.Liquid metal strain gauges (LMSG) were implanted surgically at three locations on the intact linea alba (LA) in eight horses. LA strain, strain rate, change in strain and stress were recorded during general anaesthesia, recovery from anaesthesia, standing, vocalisation, rectal palpation and at the walk, trot and canter. LA stress was quantitated using an in vitro tensiometric technique. Stress-strain responses differed significantly (P < 0.05) with location, but each described a characteristic relationship for viscoelastic tissues. Maximum peak stress, peak strain and change in strain occurred...
Zamos DT, Honnas CM, Hoffman AG.Arthroscopic examination of structures within the plantar pouch of the tarsocrural joint was accomplished via portals in both the plantaromedial and plantarolateral aspects of the joint. Flexion and extension of the tarsus while examining the joint through either portal allowed observation of the proximal and plantar aspects of the lateral and medial trochlear ridges, the trochlear groove, the caudal aspect of the distal tibia, and the deep digital flexor tendon (DDFT) in its sheath. From a plantarolateral portal, the plantar talocalcaneal ligament and the plantar aspect of the lateral malleol...
Karlström K, Essén-Gustavsson B, Hoppeler H, Straub R, Weishaupt M.In order to investigate possible differences in variables defining capillary supply of skeletal muscle derived from two methods, the electron-microscopical and the amylase-PAS histochemical methods were applied in a study of horse and steer muscles. Samples from several locomoter muscles were taken at slaughter from one horse and one steer, divided into two and prepared separately for the two techniques. It was found that there was no difference between the two methods in the values for the capillary-to-fibre ratio. Values for mean fibre area, on the other hand, were significantly higher in th...
Barrett EJ, Munsterman AS, Hanson RR, Jackson RL.To compare in vitro strength and failure characteristics of a tendon implant against a 3 loop pulley suture pattern for equine superficial digital flexor tendon (SDFT) laceration repair. Methods: Experimental. Methods: Cadaveric equine forelimb SDFT (n = 16). Methods: One tendon of each of 8 pair of SDFT was randomly selected for repair with either the 3-loop pulley (3LP) suture pattern using 2 polydioxanone or with 4 stainless steel suture and anchor implants (SA). Ultimate load to failure, mode of failure, gap at failure, and load to 2 mm gap were obtained using a materials testing sys...
Woodie JB, Ruggles AJ, Litsky AS.To evaluate 2 methods of midbody proximal sesamoid bone repair--fixation by a screw placed in lag fashion and circumferential wire fixation--by comparing yield load and the adjacent soft-tissue strain during monotonic loading. Methods: Experimental study. Methods: 10 paired equine cadaver forelimbs from race-trained horses. Methods: A transverse midbody osteotomy of the medial proximal sesamoid bone (PSB) was created. The osteotomy was repaired with a 4.5-mm cortex bone screw placed in lag fashion or a 1.25-mm circumferential wire. The limbs were instrumented with differential variable relucta...
Palmer SE.Lameness of the Standardbred racehorse is a function of rigorous training programs, year-round racing schedules, hard racetrack surfaces, and the draft load. In this article, principles of lameness diagnosis and treatment are reviewed, with emphasis upon common or unique problems of the trotter and pacer. The role of physical therapy as an adjunct to medical and surgical treatment of lameness is described. Options for management of chronic pain are discussed, and a limited glossary of descriptive terms that are unique to harness racing is provided.
Salinger A, Mochal-King C, Clinton K, Priddy LB, Elder S, Fontenot R, Eddy A, Wills R, Jaffe M.Frontal plane slab fractures account for the majority of third carpal bone (C3) fractures in racing and performance horses. Recommended treatment is stabilization with a lagged AO cortical screw. Associated complications are fragment splitting, fragment spinning, and irritation of dorsal soft tissue structures. A novel, headless, cannulated screw with interlocking threads the Headless Compression Screw Fastener (HCSF) has been developed to resist multidirectional forces and bending moments; however, it has not been applied in the horse. Simulated C3 frontal plane slab fractures were created in...
Seeherman HJ, Morris E, O'Callaghan MW.Discovering the cause of poor performance in racehorses can often represent a considerable challenge eluding the more common diagnostic techniques available at the racetrack. Application of sports medicine techniques to these problem cases can aid in the diagnosis of poor performance. Central to the development of this capability has been the use of highspeed treadmills, allowing the racehorse to be evaluated in the controlled laboratory setting, at exercise intensities equivalent to those of racing. Video and cinematographic gait analysis can be used in the diagnosis of subtle lameness condit...
Mendoza L, Franck T, Lejeune JP, Caudron I, Detilleux J, Deliège B, Serteyn D.Osteochondrosis (OC) disease appears to be multifactorial in origin, including skeletal growth rates, nutrition, endocrinological factors, exercise, biomechanics, and other environmental factors. Endocrinological and metabolic factors seem to have an important role in the pathogeny of OC like the Wnt signaling pathway. One of the regulators in the Wnt signaling pathway is the sclerostin glycoprotein. The aim of this study was to investigate the sclerostin blood concentration according to the evolution of the disease, the environment, and the age but also its use as a possible biomarker for OC ...
Wheat JD, Pascoe JR.Problems involving the management of acute traumatic rupture of the equine suspensory apparatus include loss of blood flow to the foot, proper immobilization, and pressure sores from casts. A technique utilizing a board splinting device attached to the affected limb at the toe and subsequent corrective shoe support provides immobilization, prevents dropping of the fetlock, can be applied to the standing animal, and allows frequent changing of the bandages, if necessary.
Bo Minelli L, Acone F, Zedda M, Sanna L.The retractor penis muscle originates from the vertebrae in pigs, horses, cattle and goats; it arises from the rectum in sheep. In all the species considered, sensitive innervation was found. This was represented by encapsulated receptors. Nervous vegetative supply, made up of isolated or assembled ganglion cells, was also present. Among the numerous sensory nerve endings found in pigs, goats and sheep were Pacinian, Pacinian-like, Golgi-Mazzoni corpuscles and Krause's end bulbs (genital corpuscles). Few Pacinian and Pacinian-like corpuscles were found in cattle and horses. A hypothesis on the...
Ivancic PC.We reported two cases of jockeys who sustained fracture/dislocation of the mid-thoracic spine due to traumatic falls during horse racing. We examined the injury mechanism based upon the patients' diagnostic images and video footage of races, in which the accidents occurred. Admission imaging of patient 1 (a 42 years old male) revealed T5 burst fracture with bony retropulsion of 7 mm causing complete paralysis below T5/6. There existed 22° focal kyphosis at T5/6, anterolisthesis of T5 relative to T6, T5/6 disc herniation, cord edema and epidural hemorrhage from T4 through T6, and cord injury f...
Whitton RC, Rose RJ.Medial palmar intercarpal ligaments (MPICL) and dorsomedial intercarpal ligaments (DMICL) from the midcarpal joints of 11 adult horses in training were examined histopathologically. These were compared with ligaments from seven horses less than 12 months of age, and 10 grossly enlarged DMICLs of adult horses. Tearing of the MPICL was observed in 15 of 22 joints from adult horses. Collagen fibre bundles of the MPICLs generally were disorganized and poorly aligned, and there were large areas of loose connective tissue. In young horses there was more parallel alignment of collagen bundles and les...
Legg KA, Colborne GR, Gee EK, Rogers CW.To evaluate the elastic modulus of various ligaments of the forelimbs of cadaveric horses. Methods: 408 ligaments from 37 forelimbs of 10 Thoroughbred cadavers and cadavers of 9 other horse breeds. Methods: Collateral ligaments and straight and oblique sesamoid ligaments were harvested from the proximal interphalangeal, metacarpophalangeal, carpal, and elbow joints of both forelimbs of all 19 horses. Ligament dimensions were measured, and the elastic modulus was determined by tensile testing the ligaments with a strain rate of 1 mm•s. Results: Elastic modulus of the ligaments differed signif...
Pugliese BR, Brisbois AL, Size KJ, St George LB, Hobbs SJ, Kirker-Head CA.To evaluate the ability of novel legwear designed to limit extension of the metacarpophalangeal joint (MCPJ) to redirect loading forces from the flexor apparatus during walk, trot, and canter on a treadmill and during unrestrained and restrained activity in a stall. Methods: 6 adult horses without musculoskeletal disease. Methods: Legwear-derived force data were recorded under 4 conditions: inactive state (unlimited legwear extension) and 3 active (restrictive) states (mild, 30° extension; moderate, 20° extension; or maximum, 10° extension). Associations between peak legwear loads and torqu...
