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.
Richardson DW, Nunamaker DM, Sigafoos RD.Arthrodesis of the metacarpophalangeal joint was attempted in 9 adult horses, using a new external skeletal fixation device and autogenous cancellous bone graft. Four horses had excellent results, 2 horses had fair results, arthrodesis failed in 2 horses, and 1 horse fractured the third metacarpal bone. The advantages of the technique included minimal surgical trauma to the area of injury, immediate rigid fixation of the metacarpophalangeal joint, and access for treatment of soft-tissue lesions at the site of injury. Although pin loosening and pin-track infection were complications when the de...
Denny HR, Barr AR, Waterman A.A series of 25 horses with olecranon fractures are reviewed. Twenty-one cases were treated surgically by the application of a tension band plate to the caudal aspect of the ulna. Seventy six per cent of these regained full limb function. The results of treatment are compared with two other series of conservatively and surgically treated cases.
Sullins KE, McIlwraith CW.Transverse or oblique midshaft tibial osteotomies were created in 11 foals. The osteotomies were repaired during the same procedure using external skeletal fixation in either full splint or 3-dimensional (3-D) tent configurations. Four of the six foals receiving the full splint fixator recovered to full soundness; two were euthanized because of complications. The foals receiving the 3-D tent configuration would not bear weight on the limbs and consequently suffered significant secondary fracture disease. These foals were euthanized for humane reasons before the scheduled termination of the pro...
Fischer AT, Stover SM.Third carpal sagittal fractures were found to be related to racing injuries in 10 of 12 horses. These fractures occurred most commonly on the medial aspect of the bone. A dorsoproximal-dorsodistal view of the carpus was required to visualize the fracture in all cases. Healing of the fracture required periods of rest of up to one year. Conservative management of these fractures resulted in return to function in 7 of 12 horses.
Dik KJ, Merkens HW.Eleven horses with unilateral distension of the sheath are reported with emphasis on the use of plain and contrast radiography in diagnosis. Six had associated bony abnormalities of the sustentaculum tali, and two of these showed destructive or mixed destructive and proliferative lesions resulting from osteomyelitis. One horse had a fracture of the sustentaculum. In three horses proliferative changes were found. Bony changes were best demonstrated on a dorsomedial-plantarolateral oblique view. Contrast radiography of the tarsal sheath was performed in five cases without, and two horses with, a...
Bertone AL, McIlwraith CW.Arthroscopic approaches to the scapulohumeral joint were developed in four clinically normal, live horses (5 limbs) to determine their usefulness for evaluation and potential surgical treatment of intraarticular lesions. The articular surface of the entire glenoid, cranial humeral head (medial and lateral) and caudolateral humeral head, as well as the synovial membrane, could be closely examined from an arthroscopic portal cranial to the infraspinatus tendon. The caudomedial humeral head could be examined partially. Cranial and caudal instrument portals allowed good surgical access to the enti...
Cahill JI, Goulden BE.Recent research on the muscular and nervous changes which occur in idiopathic equine laryngeal hemiplegia has indicated that many of the traditional concepts of the aetiology of this disease are erroneous. In light of the new knowledge gained, the various predispositions and possible causes of laryngeal hemiplegia are discussed, and it is suggested that the underlying mechanism of axonal damage in this neuropathy of horses may be related to abnormal energy metabolism in the axon.
Manohar M, Gustafson R, Nganwa D.Effects of 1.55 minimum alveolar concentration isoflurane O2 anesthesia (2.03% end-tidal isoflurane) on blood flow in the up-(nondependent) and down-(dependent) positioned skeletal muscles were studied at 60, 120, and 180 minutes in 6 healthy isocapnic ponies in right lateral recumbency on a nonpadded hardwood floor. Measurements were made, using 15-micron diameter radionuclide-labeled microspheres injected into the left ventricle, and comparisons were made with data obtained from ponies in the conscious state. Isoflurane administration caused a sharp reduction in cardiac output and systemic p...
May SA, Wyn-Jones G.The use of markers placed over the tuber coxae on each side of a horse to aid identification of the relative movement of these structures at the trot, for teaching and research purposes, is described. In each case of hindleg lameness studied, the tuber coxae on the lame side showed a consistent increase in vertical displacement relative to that of the contralateral limb, and a characteristic pattern of movement throughout the stride irrespective of the site or cause of pain.
Leach DH, Sprigings EJ, Laverty WH.Standard univariate and bivariate statistical methods and two multivariate methods, stepwise regression and factor analyses, were used to analyze 17 stride-timing measurements of 22 racing Thoroughbreds filmed at the beginning of races. All horses were in a right-lead transverse gallop. Data were extracted from frame-by-frame analysis of 16-mm film taken with a high-speed camera. The mean stride duration was 0.405 s and the mean stride frequency was 2.47 strides/s. Stride duration had a higher correlation to the suspension-phase duration (r = 0.864) than to stride-stance-phase duration (r = 0....
Pintea V, Ganţă C.The mm. lumbricales and the mm. capsulares of the shoulder and hip joints of the horse are rich in neuromuscular spindles (NMS). The mm. interossei of the pig, but not of the horse, have NMS too. In the m. orbicularis of the eye, m.hyo-epiglotticus and the m. palatinus of the horse NMS are absent. In the vestigial muscles, as m. extensor digitorum brevis and m. of Thiernesse, NMS are absent too. A role of modulator for the proximal muscles of the limbs by the distal muscles is hypothesized, as well as the absence of NMS in striated muscles not involved in locomotion.
Kelso TB, Hodgson DR, Visscher AR, Gollnick PD.Several biochemical components of the white portion of the gastrocnemius (WGM), plantaris (PM), and soleus (SM) muscles of the rat and middle gluteal (MGM) muscle of the horse were compared based on wet and dry weight, protein, and total creatine concentrations ([TCr]). The water content was similar for the rat hindlimb muscles, however, the concentrations of protein, ATP, phosphocreatine (PCr), creatine, and glycogen ranked as SM less than PM less than WGM for all reference bases except total creatine. In contrast, concentrations of ATP, creatine, and PCr were similar in all muscles studied w...
Bukowiecki CF, Bramlage LR, Gabel AA.Forty-eight limbs of 12 freshly euthanized horses were used to generate data on the strength of the equine suspensory apparatus. The point of failure of the suspensory apparatus of each limb was determined. Immediately before euthanasia, 6 of the 12 horses (thoroughbreds and standardbreds) had been engaged in active training or racing, and six horses in stall and/or pasture activity. In the actively training or racing horses, the point of acute failure of the suspensory apparatus was within the proximal sesamoid bones in 20 (83%) limbs (resulting in 17 apical fractures, 2 basilar fractures, an...
Moll HD, Slone DE, Humburg JM, Jagar JE.Three horses and three ponies were treated for traumatic luxation of the proximal intertarsal or tarsometatarsal joint. In each case, there were fractures of one or more tarsal bones. Three of the animals had disruption of one of the collateral ligaments. Five animals were treated by closed reduction and external coaptation. One pony was treated by open curettage, a cancellous bone graft, and cast immobilization. No internal fixation was used in any of these animals. From this series of cases, it would appear that closed reduction and external coaption alone is adequate treatment for most case...
Schamhardt HC, Merkens HW.A method was developed to quantify the ground reaction force pattern of the horse. A number of selected force amplitudes and peak-time positions in the normalized stance phase of left and right contralateral limbs were used to calculate symmetry indices. Data from each limb were compared with those of a 'standard horse' resulting in limb indices. The combination of amplitude and peak-time symmetry and limb indices yielded one H(orse)INDEX. These indices were useful for comparison of different horses and for the evaluation of lameness and treatment.
van Gurp M, Schamhardt HC, Crowe A.A model consisting of a spring loaded by a time-dependent mass is presented simulating the vertical and longitudinal horizontal ground reaction force patterns obtained from the hindlimb of a walking horse.
Bristol DG, Fubini SL.Lipomas involving the musculoskeletal system were seen in 3 horses. The lipomas were on the thorax of 2 horses and the stifle of the third horse. The thoracic lipomas were surgically removed. No recurrence has been noted by 8 months in either case. The lipoma on the stifle had invaded the surrounding tissue and the horse was euthanatized. Unlike mesenteric lipomas, which occur in older horses, these lipomas all occurred in horses less than 2 years of age.
Zamos DT, Hunt RJ, Allen D.Fractures of the distal radius in two horses were repaired by open reduction and interfragmentary compression using screws placed in a lag fashion. One horse had a complete oblique fracture of the medial aspect of the epiphysis of the distal radius and was sound for riding 32 months after surgery. The other horse had an open spiral comminuted fracture with medial displacement of the distal radial fragment. Laminitis developed in the contralateral limb and this horse was euthanatized 5 weeks after surgery.
Meijer AE, van den Hoven R, Wensing T, Breukink HJ.In this communication, the results of an enzyme histochemical study on m. gluteus medius of horses, sensitive to exertional myopathy, during attacks of rhabdomyolysis are presented. The activity and location of about 25 enzymes were examined. In the present report, the early metabolic changes are discussed. Within 6 min after an attack, some large rounded fibres (approximately 2%) were seen, which showed an intense red staining in the haematoxylin and eosin sections. These hypercontracted fibres showed an increase in activity of mitochondrial adenosine triphosphatase, indicating the presence o...
Kakas R, Stockdale S, Carr A.The research article discusses a case study of a young boxer diagnosed with septic physitis of the humerus, and the MRI findings observed which assisted in identifying the condition. Introduction […]
Nicoll RG, Wood AK, Martin IC.Observations were made in dorsal and sagittal planes of the ultrasonographic mean gray scale of the flexor tendons and ligaments of the metacarpal regions of 5 Thoroughbred geldings, during weight bearing and nonweight bearing. In images made when the horses were nonweight bearing, the mean gray scale of the superficial and deep digital flexor tendons and accessory ligament was significantly reduced, but that of the interosseous medius muscle (suspensory ligament) was not. When relaxed, collagen fiber bundles in the tendons and ligaments acted as diffuse, rather than specular, reflectors of ul...
Tew WP, Hackett RP.Synovial fluids from 72 equine joints were examined for the presence of cartilage debris, and these findings were compared to findings from visual inspection of the articular cartilage surfaces at necropsy. Synovial fluids from 25 joints with visual cartilage damage contained one or more large particles of articular cartilage. Cartilage fragments were not found in synovial fluids from 42 of the 47 apparently normal joints; thus, a correlation may exist between cartilage debris in the synovial fluid and lesions of the articular surfaces.