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.
Becht JL, Park RD, Kraft SL, Steyn PF, Wrigley RH.Effective radiographic interpretation requires a veterinarian who is knowledgeable of equine limb anatomy and the various principles that affect the resulting image. The normal and its variations must be recognized and understood before the abnormal can be confidently identified as pathologic. Proper patient positioning and sound radiographic technique are mandatory if reliable diagnostic radiographs are to be produced. This review emphasizes equine foot radiographic variations of normal and pseudolesions that occur with commonly used radiographic views performed in equine practice.
Twardock AR.It is well known that skeletal scintigraphy is an imaging modality with high sensitivity but low specificity. Sites of IRU provide good evidence of increased bone turnover but not its specific cause. Results of lameness workups, blocks, and other imaging techniques are required to determine specific causes. Overinterpretation of causes of IRU is tempting, especially in assigning diagnoses to EIBR--adaptive or non-adaptive. Nevertheless, a quarter of a century's experience with equine skeletal scintigraphy has shown that certain patterns and locations can be fairly predictive of certain patholo...
Tucker RL, Sande RD.There is a growing interest in the use of computed tomography (CT) and magnetic resonance (MR) imaging in equine orthopedic patients. It is well established that CT and MR imaging offer superior diagnostic information in a wide variety of musculoskeletal injuries in human beings and small animals. The highly detailed cross-sectional images obtained with these two modalities can often demonstrate pathologic changes undetected with other common imaging techniques. Based on their multiple applications in human beings and small animals, CT or MR imaging may prove to be the optimal diagnostic imagi...
Reef VB.Until recently, it was difficult to critically evaluate tendon healing in vivo. Superficial digital flexor tendon injuries were considered healed when the injured tendon was cold, non-painful, adequate time had passed for tendon healing to occur, and no recurrence of the injury was detected when the horse returned to athletic work. This article discusses how ultrasonography has revolutionized the diagnosis, treatment, and management of tendon injuries.
Klomkleaw W, Kasashima Y, Kobayashi A, Fuller GA, Morimoto M, Nakade T, Muto M, Oba T, Hamlin RL, Yamaguchi M.Tubular aggregates (TAs) originate from the sarcoplasmic reticulum (SR) and form polymorphic double (or single) -walled structures in cross section. TAs are involved in various human skeletal muscle disorders including periodic paralysis, congenital myasthenic syndromes, inflammatory myopathies, and malignant hyperthermias. Horse lumbrical muscle (LM) is a slender fusiform muscle that shows varying degrees of regression due to its limited activity in the limb. Double-walled TAs were found in degenerating spindle fibers and with a range of 80-116 nm (average 92 nm, n=135) for outer layer and 50...
Sacchi L, Corona S, Gajadhar AA, Pozio E.The nurse cell-larva complex of nematodes of the genus Trichinella plays an important role in the survival of the larva in decaying muscles, frequently favouring the transmission of the parasite in extreme environmental conditions. The ultrastructure of the nurse cell-larva complex in muscles from different hosts infected with T. nativa (a walrus and a polar bear), T. spiralis (horses and humans), T. pseudospiralis (a laboratory mouse) and T. papuae (a laboratory mouse) were examined. Analysis with transmission electron microscope showed that the typical nurse cell structure was present in all...
Rodgerson DH, Spirito MA.Instability of the collateral ligaments of the carpal or metacarpophalangeal joint occurred in 2 foals. The instability was repaired using commercial suture anchors. In foals, commercial suture anchors combined with external coaptation can be used successfully to repair collateral ligament instability of the carpus or the metacarpophalangeal joint.
Meershoek LS, Roepstorff L, Schamhardt HC, Johnston C, Bobbert MF.Tendon injuries are an important problem in athletic horses and are probably caused by excessive loading of the tendons during demanding activities. As a first step towards understanding these injuries, the tendon loading was quantified during jump landings. Kinematics and ground reaction forces were collected from the leading and trailing forelimbs of 6 experienced jumping horses. Joint moments were calculated using inverse dynamic analysis. It was found that the variation of movement and loading patterns was small, both within and between horses. The peak flexor joint moments in the coffin a...
Billinghurst RC, Buxton EM, Edwards MG, McGraw MS, McIlwraith CW.To develop an antibody that specifically recognizes collagenase-cleaved type-II collagen in equine articular cartilage. Methods: Cartilage specimens from horses euthanatized for problems unrelated to the musculoskeletal system. Methods: A peptide was synthesized representing the carboxy- (C-) terminus (neoepitope) of the equine type-II collagen fragment created by mammalian collagenases. This peptide was used to produce a polyclonal antibody, characterized by western analysis for reactivity to native and collagenase-cleaved equine collagens. The antibody was evaluated as an antineoepitope anti...
Brama PA, Bank RA, Tekoppele JM, Van Weeren PR.Subchondral bone provides structural support to the overlying articular cartilage and plays an important role in osteochondral diseases. There is growing insight that the mechanical features of bone are related to the biochemistry of the collagen network. In this study the effect of exercise on water, calcium and the collagen network (total collagen, lysyl-hydroxylation, hydroxylysylpyridinoline, and lysylpyridinoline crosslinks) of subchondral bone at two differently loaded sites (site 1: intermittently loaded; site 2: constantly loaded) is investigated in foals. Exercise influenced calcium c...
Brama PA, Barneveld A, Karssenberg D, Van Kampen GP, van Weeren PR.A recently developed indenter system that aims at determination of local structural properties of the cartilage surface was evaluated for suitability in the horse. To this aim, maximum indenter force was measured of the articular surface and related to biochemical characteristics of the cartilage at different sites of the distal metacarpal bone (MC). Significant topographical variation exists in structural properties of the articular surface of the MC. The dorsal margin showed a significantly lower maximum indenter force than more centrally located areas, indicating an increased compliance und...
Schnewlin M, Lischer C.This article gives a general overview on a new therapy in equine orthopedics. In human medicine extracorporal shock wave therapy (ESWT) is used for lithotripsy of stones of the urologic system and also in orthopedics. In equine medicine the therapy is almost exclusively applied for the treatment of orthopedic problems. The main indications are proximal suspensory desmitis (PSD), lesions of tendons and ligaments, osteoporotic changes and spavin. In this paper the mode of action of shock waves and the different shock wave devices are discussed. Also, some information about an ongoing clinical tr...
Bodó G, Kaposi AD, Hangody L, Tóth J, Bakos Z, Lukács Z, Péntek G.Six pieces of grafts, 6.5 mm in diameter, 20 mm in length, were taken from each of 170 cadaver hindlimbs, using the cranial surface of the medial femoral trochlea for harvesting. The age of the horses varied between 4 months and 23 years. 30 limbs under the age of 12 years were selected for transplantation. Three of six grafts were transplanted into the medial femoral condyle using different combinations of tunnel depth and dilation. With ageing, a significant decline in transplantability was detected. In general, mosaicplasty cannot be recommended in horses above 11 years. Based on a previous...
Hood DM, Taylor D, Wagner IP.To determine whether solar load distribution pattern on a solid nondeformable ground surface is the product of contact erosion and is the mirror image of load distribution on a deformable surface in horses. Methods: 30 clinically normal horses. Methods: Solar load distribution was compared among 25 clinically normal horses during quasistatic loading on a solid nondeformable surface and on a highly deformable surface. Changes in solar load distribution patterns were evaluated in 5 previously pasture-maintained horses housed on a flat nondeformable surface. Changes in solar load distribution cre...
Nash RA, Nunamaker DM, Boston R.To evaluate stiffness and bone-pin interface stress for a transcortical tapered-sleeve pin (TSP) that incorporates bilateral tapered sleeves over a transcortical pin. Methods: 14 third metacarpal bones (MCIII) collected from adult horses of various breeds. Methods: Each MCIII was cut in half to provide 2 test specimens. Pins (conventional and TSP) of 3 diameters (6.35, 7.94, and 9.50 mm) were inserted in specimens (3 specimens for each diameter and each type of pin). The test fixture simulated a typical sidebar-span skeletal fixation device for horses. Single cycle load-deflection tests were p...
Khumsap S, Clayton HM, Lanovaz JL.To measure the effect of subject velocity on hind limb ground reaction force variables at the walk and to use the data to predict the force variables at different walking velocities in horses. Methods: 5 clinically normal horses. Methods: Kinematic and force data were collected simultaneously. Each horse was led over a force plate at a range of walking velocities. Stance duration and force data were recorded for the right hind limb. To avoid the effect of horse size on the outcome variables, the 8 force variables were standardized to body mass and height at the shoulders. Velocity was standard...
Swerczek TW, Donahue JM, Hunt RJ.Scedosporium prolificans was associated with arthritis and degenerative osteomyelitis in a 6-year-old Thoroughbred racehorse. The horse was suspected to have an inflammatory lesion of the interosseous tendon, but treatment had resulted in only a minimal response. Shortly after diagnostic arthrocentesis of the left metacarpophalangeal joint was performed, the joint became severely swollen, and radiography of the area revealed lysis of the distal end of the third metacarpal bone, the proximal sesamoid bones, and the proximal end of the proximal phalanx. The horse did not respond to treatment and...
Bell RA, Nielsen BD, Waite K, Rosenstein D, Orth M.Seventeen Arabian weanlings were used to determine the influence of housing on third metacarpal bone mass. Animals were separated into three treatment groups: Pasture (n = 6), Stall (n = 5), and Partial-Pasture (n = 6). Radiographs of the left third metacarpus were taken every 28 d to determine radiographic bone aluminum equivalence (RBAE). Serum was collected every 14 d and analyzed for osteocalcin, carboxyterminal telopeptide of type I collagen (ICTP), and keratan sulfate. Hip and wither height, BW, and cannon circumference were measured every 28 d. Lateral RBAE in the pastured group increas...
Schumacher J, Schumacher J, de Graves F, Steiger R, Schramme M, Smith R, Coker M.The response of horses, with solar pain in the dorsal or palmar aspect of the foot, to 6 or 10 ml local analgesic solution administered into the distal interphalangeal (DIP) joint was examined. Lameness was induced in 7 horses by creating solar pain in the dorsal aspect of one forefoot and, at another time, the palmar aspect of the other forefoot with set-screws inserted into a custom-made shoe. Horses were videotaped trotting before and after application of set-screws and, in separate trials, after 6 or 10 ml local analgesic solution was administered into the DIP joint. Lameness scores were a...
Suwannachot P, Verkleij CB, Kocsis S, van Weeren PR, Evertst ME.The purpose of the present study was to determine whether training and detraining affect the Na+,K+-ATPase concentration in horse skeletal muscles, and whether these effects are specific for the muscles involved in the training programme. Twenty-four Dutch Warmblood foals age 7 days were assigned randomly to 3 groups: Box (box-rest without training), Training (box-rest with training: short-sprint) and Pasture (pasture without training). Exercise regimens were carried out for 5 months and were followed by 6 months of detraining. Five of the foals in each group were subjected to euthanasia at ag...
Wagner IP, Hood DM, Hogan HA.To determine whether the bending modulus and yield strength of the outer stratum medium (SM) differed from those of the SM zona alba (SMZA) and to what degree they differed. In addition, a comparison was made among our values and values reported elsewhere. Methods: 10 normal equine feet. Methods: A 3-point bending technique was used to determine the bending modulus and yield strength of the outer SM and SMZA. Efforts were made to minimize biological and technical factors that could influence the bending modulus. Results: Bending modulus of the outer SM was (mean +/- SD) 187.6 +/- 41.3 MPa, whe...
Faber M, Johnston C, Schamhardt H, van Weeren R, Roepstorff L, Barneveld A.To determine movements of the vertebral column of horses during normal locomotion. Methods: 5 young Dutch Warmblood horses that did not have signs of back problems or lameness. Methods: Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Measurements were recorded when the horses were trotting on a treadmill at a constant speed of 4.0 m/s. Results: Flexion-extension and axial rotation were characterized by a double sinusoidal pattern of motion during 1 stride cycle, whereas lateral bending was characterized by 1 pe...
McClure SR, Glickman LT, Glickman NW, Weaver CM.To determine the accuracy and precision of dual energy x-ray absorptiometry (DEXA) for measuring bone mineral density in horses in situ. Sample Population-12 randomly selected forelimbs from 12 horses. Methods: Metacarpi were scanned in 2 planes and DEXA measurements obtained for 6 regions of interest (ROI). Each ROI was isolated and bone density measured by Archimedes' principle. Linear regression analysis was used to determine the correlation between the 2 measurements at each ROI. An additional metacarpus was measured 10 times to determine the coefficient of variation for both techniques. R...
Watt BC, Edwards RB, Markel MD, McCabe R, Wilson DG.To compare the biomechanical characteristics and mode of failure of 2 parallel-screw techniques for proximal interphalangeal joint arthrodesis in horses. Methods: Randomized block design, blocking for horse (1-5), method of screw fixation (three 4.5-mm vs two 5.5-mm), side (left limb vs right limb), and end (front limb vs hind limb). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. Methods: Twenty limbs (10 limb pairs) from 5 equine cadavers. Methods: A combined aiming device was used to facilitate consistent screw placement. Three parallel 4.5-mm...
Gawrylash SK.Thyroid hyperplasia and musculoskeletal deformity, described in foals in western Canada, has not been recognized as a common cause of neonatal foal mortality in Ontario. A case is reported from Ontario, with clinical and histopathological findings consistent with the syndrome described in western Canada. Résumé — Hyperplasie thyroïdienne et déformation musculosquelettique chez une pouliche Standardbred. L’hyperplasie de la thyroïde et la déformation musculosquelettique, décrites chez les poulains dans l’ouest du Canada, n’a pas été reconnue comme cause fréquente de mortalité...
Levine DG.The first weeks of life are critical in many aspects, and the musculoskeletal system is no exception. Being able to stand and nurse within hours of life is necessary for survival. Laxity, flexural deformities, and skeletal immaturity can all make it difficult for neonates to ambulate. The increased vascularity to bones and cartilage mixed with the newly forming immune system also make neonates susceptible to infections that we rarely see in adult animals. This article concentrates on orthopedic conditions seen in the first 2 weeks of life.
Dzierzecka M, Charuta A.The bone mineral density (BMD) and the bone mineral content (BMC) in the bone tissue of the bilateral first phalanges of horses' thoracic limbs were analysed. The research material consisted of isolated pastern bones derived from 22 horses. The research was conducted with the use of a Norland model Excell Plus densitometer (Fort Atkinson WI, USA), using affinited beam X-ray technology and an animal research programme (Research Scan, 3.9.6. version) at the following parameters: scanning resolution of 1.5 x 1.5 mm, scanning speed 60 mm/s. The differences between BMC and BMD values in bilateral f...
Biggi M, Dyson S.There are no data concerning the accuracy of conventional and computed or digital radiography for evaluation of the equine foot. Objective: To compare conventional film-screen and computed radiography with magnetic resonance imaging (MRI) for detection of distal border fragments of the navicular bone; and to establish which type of fragment was more likely to be detected radiologically. Methods: Horses were included if forelimb lameness was localised to the foot and both radiography and high-field MR images had been acquired. Horses were divided into 2 groups based on acquisition of convention...
Bramlage LR, Hanes GE.A 3-year-old Thoroughbred mare was examined because of hindlimb lameness from incomplete fracture of the tibia, which became a complete diaphyseal fracture during the examination. The fracture was repaired by open reduction and internal fixation with lag screws and 2 neutralization plates. A cranial approach was used and the plates were placed craniolateral and medial on the tibia. At 18 months after surgery, there was no evidence of complications resulting from the fracture or its repair. It was concluded that a cranial approach with craniolateral and medial plate placement allows easier inse...
Blikslager AT, Bristol DG.A 3-month-old foal was examined because of lameness and fracture of the left lateral trochlear ridge of the femur. Arthroscopy of the left femoropatellar joint was elected. After induction of general anesthesia and placement of the foal in dorsal recumbency, it was noticed that the left hind limb was extended at the tibiotarsal joint and flexed at the femorotibial joint. Avulsion fracture at the origin of the peroneus tertius tendon was diagnosed. Fracture fragments were excised. The horse had mild left hind limb lameness at the time of follow-up evaluation 1 year after discharge.
Crawford KL, Finnane A, Greer RM, Phillips CJC, Bishop EL, Woldeyohannes SM, Perkins NR, Ahern BJ.Worldwide, musculoskeletal injuries remain a major problem for the Thoroughbred racing industry. There is a strong interest in developing training and management strategies to reduce the impact of musculoskeletal injuries, however, progress has been limited by studies reporting conflicting findings, and a limited understanding of the role of different training methods in preventing injury. There is little data on patterns of rest periods and exercise data and how these vary between trainers. This prospective study of two-year-old racehorses was conducted in Queensland, Australia and involved w...
Snow DH, Munro CD, Nimmo MA.The effects of 7 weekly injections of the anabolic steroid nandrolone phenylpropionate (400 mg) were investigated in 4 healthy, mature geldings. Measurement of body weight, nitrogen retention and plasma urea failed to demonstrate a consistent anabolic effects. Examination of biopsies from the semitendinosus and biceps femoris muscles showed no alteration in water content or glycogen concentration with treatment. Similarly no changes were found in the activities of 6 muscle enzymes. However, a significant increase in the proportion of fast twitch low oxidative fibres of the biceps femoris was o...
Haupt JL, Caron JP.To compare the proportion of the proximal recess of the navicular bursa that could be examined through a single endoscopic portal and the severity of iatrogenic lesions between conventional and modified approaches. Methods: Descriptive study. Methods: Equine cadaver forelimbs (n=16). Methods: Arthroscopic access to the navicular bursa in 1 limb of each pair was by a conventional approach and in the other limb, by a modified approach using sharp dissection through the distal digital flexor sheath, immediately palmar to the T ligament. The time required to access the bursa and the estimated prop...
Lin YL, Brama PA, Kiers GH, van Weeren PR, DeGroot J.The objectives of the present study were to test the hypotheses that: (1) the composition of the extracellular matrix of the equine superficial digital flexor tendon (SDFT) shows great functional similarities with articular cartilage, i.e. that significant differences exist in biochemical composition of differently loaded areas (which in the case of tendons may be more apparent as tendon shows more obvious differences than cartilage); and (2) that, as in articular cartilage, no substantial alterations in biochemical composition take place during ageing once adulthood has been attained. Tendon ...
Ramsay WN.The non-haem iron concentration was estimated in post-mortem liver samples from 51 horses (age range 1-25 years). Two were normal and 49 had been suffering from conditions that were not expected to have had long-term effects on iron metabolism. Muscle samples (splenius and biceps femoris) from 23 of these horses were also analysed. There was a highly significant age-related increase in the non-haem iron concentration in the liver (r = 0.635, p < 0.001), but not in the muscles, in which the iron concentration was much lower than in the liver.
Gerard MP.This article provides an overview of foot anatomy and physiology, with a focus on fundamental knowledge. The foot is defined as the epidermal hoof capsule and all structures enveloped by the capsule. The anatomy is described using terminology published in Nomina Anatomica Veterinaria.
Scott EA, Thrall DE, Sandler GA.Vascular supply of the equine forelimb was partially disrupted by ligation of the medial palmar and medial palmar digital arteries. Vascular architecture was evaluated before and after ligation by angiography. It was apparent from the present study that existing collaterals or newly formed collaterals, or both, were sufficient to maintain limb viability.