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.
Webbon PM.The normal appearance of the superficial (SFT) and deep (DFT) digital flexor tendons was described and the difference between their histological structures was emphasised. Further differences were recognised between different sites from the same tendon and between tendons in the fore and hind limbs of the same animal. Both of the tendons underwent changes with age but although a number of alterations in the histological appearance were described, a particular change, involving a patchy loss of stainable nuclei, was found at the common site of SFT injuries. While this appearance has been seen i...
Owen R, Maxie LL.Quadriplegia of 4 days' duration in a 3-week-old foal was caused by displacement of the dens of the axis due to a fracture at the dens growth plate. The displacement was reduced and was immobilized surgically. Two months after surgery, the foal was able to rise, walk, and trot without apparent neurologic deficiencies. Three years later, the only defect was a mild gait disturbance in the left hindlimb seen at a canter and a gallop.
Gunn HM.The mean fibre areas of samples from m. semitendinosus, m. diaphragma and m. pectoralis transversus of thoroughbred horses and greyhounds have been compared with those in similar samples from other members of their species. Athletes (greyhounds and thoroughbreds) have larger fibres in the semitendinosus and diaphragm than their fellows. However, the mean area of pectoralis transversus is similar in the two types of animal within each species. During growth the mean fibre areas increase to a greater extent in athletes than in non-athletes. Detraining adult greyhounds for a period of one year di...
Valdez H, Adams OR.After preliminary studies on cadavers, a surgical approach was developed for removal of the medial meniscus, offering maximal exposure and minimal trauma to the articular surfaces of the medial tibial plateau and femoral condyle. Medial meniscectomy was then performed on 10 clinically normal horses that had been given general anesthesia. Nine horses were euthanatized at intervals of 1 to 6 months, and the joints were evaluated grossly and histologically. (One horse will be examined 1 year after surgery). Medial meniscus tears were diagnosed in 5 horses; medial meniscectomy was done on 4 horses...
Wentink GH.The locomotor pattern of the hind limb of seven horses has been studied in intact animals and after transection of the following structures: the peroneus tertius tendon, the cranial tibial muscle, both cranial tibial muscle and peroneus tertius tendon, and the superficial digital flexor tendon. The investigation was carried out by high speed cinematography and electromyography. It is concluded that (1) the muscles and tendons over the cranial aspect of the tibia play an important role during the support phase; (2) the movements of the hind limb may be performed without the action of the crania...
Webbon PM.Skin temperature measurements were recorded of the legs of 13 racehorses between 2 and 5 years old. The normal limb temperature patterns are described. In over 90 per cent of the normal horses the difference between contralateral limbs was less than 1 degree C, but in the remainder differences of up to 8 degree C were recorded due to the excessive cooling of one limb. One horse had a constant temperature elevation of one foreleg, but it remained in training for 7 weeks without any obvious ill effects. Because of the small numbers of horses in the survey and their freedom from tendon injuries i...
Littlejohn A, Blackmore DJ.The occasions, position and relative concentration of LDH iso-enzymes in the blood tissues of the thoroughbred horse were determined. Locomotor muscles possess a high concentration of LDH 5 whereas non-locomotor muscles have a low concentration of this iso-enzyme.
Johnson JH, Amend JF, Franklin D, Garner HE.Ultrasonic dimension gauges were implanted in the crico-arytenoideus dorsalis muscle in a mature horse. Resting and contracted muscle length and average contraction rate were measured serially in the conscious state over a period of 25 days. Results suggest that specific laryngeal muscle function in the horse may be defined with this approach. Since man and horse are both known to suffer from laryngeal hemiplegia, this experimental preparation may help provide information of benefit to both species.
Edwards GB, Jones DG.The use of a thermoplastic linear polyester polymer orthopaedic tape in the treatment of six horses, one donkey and a bull with a variety of orthopaedic problems requiring immobilisation of a limb is described.
Ambache N, Killick SW.1 Graded motor responses were elicited in isolated, desheathed, thin strips of dog, horse, pig and sheep retractor penis (RP) muscles by field stimulation with trains of 0.2 ms pulses at 10 hertz. These twitches were shown to be neurogenic in all four species, by their prompt extinction in tetrodotoxin.2 alpha-Adrenoceptor blocking drugs abolished the contractile response to noradrenaline and to tyramine in all four species.3 Motor transmission was wholly adrenergic in the horse as in the dog RP because phentolamine rapidly abolished the electrically induced twitches in both these species; but...
Chand N, Eyre P.Histamine, 2-methylhistamine (a specific H1-agonist), 5-HT, PGF2alpha, SRS-A, bradykinin (BK) and carbachol contract bronchial and tracheal smooth muscles of the horse. Isoprenaline, PGE1, E2, dimaprit and 4-methylhistamine (last two = specific H2-agonists) relaxed airways which were partially contracted to carbachol. Mepyramine (a specific H1-antagonist) selectively antagonized contractions to histamine. In the presence of mepyramine, histamine caused relaxation of airways partially contracted to carbachol. Metiamide and burimamide (specific H2-antagonists) specifically antagonized or reverse...
Kingsbury HB, Quddus MA, Rooney JR, Geary JE.The distal portion of the forelimb of the horse is provided with a stay apparatus composed of tendons, ligaments, and fascia. This stay apparatus provides the major resistance to joint flexion during the support phase of the stride. The laboratory test system described was shown to be able to reproduce in vitro limb motions and hoof forces measured with a running horse. These results indicated the stay apparatus operates in a largely passive mode, active muscle contraction apparently serving to provide rigidity only early in the support phase of the stride. The testing system described was des...
Cartee RE, Cowles WR.To determine the lines of maximum extensibility of the skin over the equine carpus, round puncture wounds were made 2.0 cm apart over the carpal area of 5 horses (7 carpi). The direction of elongation of the round puncture wound was observed and photographed. Lines of maximum extensibility that occurred over the surfaces of the equine carpus were determined to be proximal to distal, except in a small area over the accessory carpal bone where a state of anisotropism existed. In an immobilized carpus, direction of a surgical incision was not as important as it was in a mobile carpus, in which th...
Wentink GH.The movements of the right hind limb of horses with normal locomotion were studied using cinephotography and electromyography. A model of the cycle of a stride in the walk and the trot was constructed and the kinetic parameters of the segments of the limb were calculated. A good correlation was obtained between the kinetics and the periods of the cycle of a stride during which individual muscles display activity. The results of this study demonstrate that: at placing and lifting, i.e., when a change occurs in the direction of the movement of the limb; b) At the walk, the greatest forces operan...
Quintanar MN, Millar TP, Burd MA.The limb of the equine athlete is subjected to all types of various stressors during exercise. To ensure the health of the horse and to prevent the possibility of lameness, it has been a common practice to apply cold therapy to the distal limb of the horse pre- and post-exercise. Commercially available boots are widely available for the application of cold therapy. To test the effectiveness of the boot, 6 healthy performance level sport type horses were exercised at a walk, trot, and canter in a round-pen and then subjected to the application of the ice boot for 20 minutes on a treatment leg, ...
van der Harst MR, van de Lest CH, Degroot J, Kiers GH, Brama PA, van Weeren PR.A detailed and comprehensive insight into the normal maturation process of the different tissues that make up functional units of the locomotor system such as joints is necessary to understand the influence of early training on musculoskeletal tissues. Objective: To study simultaneously the maturation process in the entire composite structure that makes up the bearing surface of a joint (cartilage, subchondral and trabecular bone) in terms of biochemical changes in the tissues of juvenile horses at 2 differently loaded sites of the metacarpophalangeal joint, compared to a group of mature horse...
Rubio-Martínez LM, Redding WR, Bladon B, Wilderjans H, Payne RJ, Tessier C, Geffroy O, Parker R, Bell C, Collingwood FA.Fractures of the medial intercondylar eminence of the tibia (MICET) are scarcely reported in horses. Objective: To report the clinical and diagnostic findings, surgical treatment and outcome in a series of horses presented with MICET fracture and treated with arthroscopic fragment removal. Methods: Multicentre retrospective case series. Methods: Case records of horses diagnosed with MICET fractures that had undergone surgical treatment were reviewed. Follow-up information was obtained from re-examination visits and/or owners. Results: Twenty-one cases were identified at 9 equine hospitals betw...
Cartee RE, Cowles WR.To determine the lines of maximum extensibility of the skin over the equine carpus, round puncture wounds were made 2.0 cm apart over the carpal area of 5 horses (7 carpi). The direction of elongation of the round puncture wound was observed and photographed. Lines of maximum extensibility that occurred over the surfaces of the equine carpus were determined to be proximal to distal, except in a small area over the accessory carpal bone where a state of anisotropism existed. In an immobilized carpus, direction of a surgical incision was not as important as it was in a mobile carpus, in which th...
O'Grady SE, Dryden VC.A club foot or flexural deformity may affect a horse at any stage of life from neonate through adulthood. The emphasis of this article is on defining and recommending the appropriate farriery for flexural deformities involving the deep digital flexor tendon and the distal interphalangeal joint. Clinical management of the flexural deformity is influenced by the severity, duration, and etiology of the club foot as well as the degree and source of lameness. Also discussed is the management of mismatched hoof angles, which remains a controversial subject for both farrier and veterinarian.
Simon V, Dyson SJ.We compared the radiographic and scintigraphic findings in the third carpal bone of horses performing different work disciplines and investigated their relationship with lameness. Horses had undergone carpal radiography including acquisition of a dorsoproximal-dorsodistal oblique (DPr-DDiO) image of the distal row of carpal bones and/or scintigraphic examination of the carpi. Cause of lameness, breed, age, and work discipline were recorded. Increased opacity in the third carpal bone was graded, ratio of radiopharmaceutical uptake calculated objectively, and increased radiopharmaceutical uptake...
Grøndahl AM, Jansen JH, Teige J.Fifty-six tarsocrural joints and 94 metatarsophalangeal joints were examined, at necropsy, from horses aged < or = 2 years. Osteochondral fragments at the cranial aspect of the intermediate ridge of the distal part of the tibia were seen in six horses, and at the proximoplantar aspect of the proximal phalanx in seven horses. Defects in the proximoplantar aspect of the proximal phalanx without osteochondral fragments were seen in a further two horses. Inflammatory and degenerative changes were not observed in any of the joints examined. From the incidence and natural course of these fragment...
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...
López-Rivero JL, Diz AM, Monterde JG, Agüera E.The results from a recent study by Bruce and Schurg (1990) indicate that the gluteus medius (Gm) of the horse is a complex muscle subdivided by an internal tendinous sheet into two regions (dorsal and ventral) which may subserve different functions. In the present study, both regions were found to contain a similar proportion of histochemically-determined muscle fibre types. Fibre type composition did not generally vary over the length of the muscle at the same relative depth. In contrast, there was a significant tendency for the percentage of type I fibres to increase gradually in accordance ...
Whitton RC, McCarthy PH, Rose RJ.To describe in detail the structure of the medial palmar intercarpal ligament (MPICL), the lateral palmar intercarpal ligament (LPICL), and a dorsomedial intercarpal ligament (DMICL) of the equine midcarpal joint. Methods: Dissections of equine midcarpal joints. ANIMALS AND SAMPLE POPULATION: Ten carpal joints from eight thoroughbred horses. Methods: Detailed dissections of the midcarpal joint were performed, with particular attention paid to the MPICL, the LPICL, and the DMICL. The attachments and dimensions of these structures were recorded, as well as their behavior during joint movement. R...
Caporali EH, Kuykendall T, Stewart MC.To fully sequence and characterize equine aggrecan and confirm conservation of major aggrecanase, calpain and matrix metalloproteinase (MMP) cleavage sites. Methods: Reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends were used to generate clones that encompassed the complete equine aggrecan sequence. Clones were sequenced and compared with the equine genome database to determine intron-exon boundaries. Results: The aggrecan gene spans over 61 kb on chromosome 1 and is encoded by 17 exons. Two major variants of aggrecan were cloned; one containing 8187 bp (2728...
Nunamaker DM, Nash RA.To report development, configuration, application, and results of a tapered-sleeve transcortical pin external skeletal fixation device (TSP ESFD) for use on fractures of the distal aspect of the equine limb. Methods: Optimization analysis of a TSP ESFD was carried out with mechanical testing and review of clinical case outcomes. Methods: Cadaveric adult third metacarpal bones (MC3) for mechanical testing; horses (n=7) with severely comminuted proximal (6; P1) or second (1) phalanx fractures. Methods: Mechanical testing of methods for attachment of TSP to the sidebars were tested as well as opt...
Belloli C, Arioli F, Beretta C, Madonna M.The contractile effects of the tachykinins eledoisin, substance P and neurokinin A and B were investigated in vitro on circular and longitudinal muscle strips from horse duodenum, ileum and colon. Circular smooth muscle of the small intestine was highly responsive, large intestine circular smooth muscle less so, while longitudinal muscle from all gut segments was much less sensitive. pD2 values and intrinsic activities on small intestine circular muscle indicated differences in receptor distribution between the duodenum and ileum: NK3 and a smaller number of NK2 receptors being present in the ...
Baptiste K.The pharyngeal orifice of the equine auditory tube has not been adequately described. Its larger size and position, further rostral within the nasopharynx compared with other species, cannot be easily explained, but could be important for the proposed brain-cooling function of the guttural pouches; however, unlike other species, it may not be the sole regulator of auditory tube aeration. A 'second orifice' (representing the final entrance to the auditory tube diverticulum) deserves recognition in performing a role in air exchange between the auditory tube, diverticulum and middle ear. The resu...
Ronéus N, Essén-Gustavsson B.To determine whether performance capacity in a group of young trained Standardbreds is related to skeletal muscle characteristics and metabolic response to exercise. Methods: 13 clinically normal 2-year-old Standardbreds. Methods: Venous blood and middle gluteal muscle biopsy samples were obtained from each horse within 1 to 2 minutes after trotting at high speed for 1,600 m. Results: There was a positive correlation between plasma lactate and muscle glucose-6-phosphate (G-6-P) concentrations and trotting speed. There was a negative correlation between muscle adenosine triphosphate concentrati...
Trolinger-Meadows KD, Biedrzycki AH, He H, Werpy N.The use of magnetic resonance imaging (MRI) has led to increased clinical and research applications using 3D segmentation and reconstructed volumetric data in musculoskeletal imaging. Lesions of the deep digital flexor tendon (DDFT) are a common pathology in horses undergoing MRI. Three-dimensional MRI reconstruction performed for volumetric tendon analysis in horses has not previously been documented. The aim of this proof-of-concept study was to evaluate the 3D segmentation of horses undergoing repeated MRI at several time points and to perform an analysis of the segmented DDFTs across time....
Mettenleiter E, Meier HP, Ueltschi G, Waibl H.The possibilities for imaging soft tissue structures, especially fluid-filled cavities such as articulations, bursae or tendon sheaths, have been improved markedly by sonography in recent years. Ultrasonic examinations were performed on the common tendon sheath of the musculus flexor hallucis longus and the musculus tibialis caudalis, from the medioplantar aspect of the tarsus, in 12 sound adult draft- and warm blood horses, and in 5 animals with a distended common sheath. The diagnostic precision of the sonographic examination of the tendon sheath is excellent and is superior to conventional ...
Torrent A, Kilcoyne I, Johnson A, Affolter VK, Berryhill E, Aleman M.This report describes an unusual presentation of multicentric B-cell lymphoma with central and peripheral nerve involvement in a horse that was presented with acute onset, severe, multiple limb lameness, and muscle atrophy. This case highlights the importance of including neoplasia in the differential list in horses presenting for severe limb lameness associated with muscle atrophy, muscle fasciculations, and weakness. Présentation atypique d’un lymphome à cellules B multisystémique chez un cheval. Ce rapport décrit la présentation inhabituelle d’un lymphome à cellules B multicentriq...
Wullschleger L, Weisse B, Blaser D, Fürst AE.Four radii of different horses were tested in three-point bending and in pure torsion. Detailed finite element (FE) models of these long bones were established by means of computed-tomography (CT) images and tests simulated for both load cases. For the allocation of the local isotropic material stiffness, individual exponential functions were applied whose factor and exponent were determined solely by fitting them to the measured torsional stiffness and bending stiffness of the entire bones. These stiffness functions referring directly to the CT number and having exponents between 1.5 and 2 we...
Stiglhuber A, Breit S, König HE.The equine fetlock joint cavity shows ten pouches. The dorsal recess, which is oriented to the proximal side, is separated from those three pouches, which show to the distal direction, by several capsular folds. These folds are documented by means of sagittal sections through the fetlock joint. A medial/lateral recess is covered by the deep part of the collateral ligament of the fetlock joint. The collateral ligaments as well as the sesamoidean collateral ligaments are closely connected with the joint capsule, from which two capsular folds are separated. Between the part of the sesamoidean col...
Lacitignola L, De Luca P, Imperante A, Tommasa SD, Crovace A.The aim of this study was to evaluate the use of a single-portal endoscopic desmotomy of the PAL with the use of Arthrex - Centerline™. Ten horse distal front limbs from horses free of PAL disease were prepared for tenoscopy of the digital flexor tendon sheath (DFTS). A dual-port endoscopic desmotomy with a hook knife was performed in 5 specimens (Group A) and single port Arthrex-Centerline™ Desmotomy was performed in another 5 specimens (Group B). The performing time, judgments of the surgeon, number of blade passages, and gross anatomy were evaluated. The performing time and surgeon judg...
Campos Schweitzer A, Mespoulhès-Rivière C, Möller D, Ducharme N, Genton M, Farfan M, Rossignol F.Selective laryngeal reinnervation using the first and second cervical nerve (C1C2) is a treatment option for recurrent laryngeal neuropathy that aims to restore the function of the cricoarytenoideus dorsalis (CAD) muscle. Despite the technique's satisfying success rate, it has several limitations. These triggered the search for another potential donor nerve that could reduce CAD muscle fatigue and shorten rehabilitation. The ventral branch of the spinal accessory nerve, providing motor innervation to the sternomandibularis (SM) muscle, was identified as a potentially well-adapted nerve. Object...
DiGiovanni DL, Rademacher N, Riggs LM, Baumruck RA, Gaschen L.Palmar/plantar annular desmitis is a common disease that may be associated with adhesions and structures affecting the flexor tendons, which requires tenoscopy to diagnose. The purpose of this descriptive study was to develop a dynamic sonographic technique for evaluating the motion of normal equine flexor tendons in relation to the palmar/plantar annular ligament and to compare findings with horses previously diagnosed with palmar/plantar annular desmitis. Ten healthy adult horses were examined prospectively and the images of four horses diagnosed with palmar/plantar annular desmitis were ret...
Palmer SE.Five horses with apical and abaxial fractures of the proximal sesamoid bones were treated arthroscopically. Ipsilateral and contralateral triangulation were used to remove abaxial fragments; apical fragments were removed by ipsilateral triangulation. Excellent visibility of the fracture fragments was obtained with each method. Dissection and removal of fragments was accomplished with standard arthroscopic instruments, tendon-splitting knives, and curved scissors. Excellent functional and cosmetic results were achieved in all cases.
Ott EA, Asquith RL.Three experiments using 63 Thoroughbred and Quarter Horse yearlings were conducted to evaluate the influence of level of feeding, and protein and calculated energy content of pelleted concentrates on growth and bone development. Animals were housed in drylot paddocks and individually fed concentrates twice daily. Coastal bermudagrass (Cynodon dyctylon) hay was group-fed. Yearlings offered a corn-based concentrate (3.56 Mcal digestible energy [DE]/kg) consumed levels of dry matter similar to yearlings fed a mixed-grain concentrate (3.32 Mcal DE/kg but consumed slightly more digestible energy. N...
Spurlock GH.This article deals with the diagnosis and treatment of tendon lacerations. Tendon healing, with its implications relative to treatment, is discussed. The various pros and cons of suturing severed tendons are addressed as well as methods of immobilizing the injured limb. The need for prompt diagnosis and aggressive treatment of tendon sheath injuries is also discussed.
Gill KK, Kroeger EA.Equine airway smooth muscle is innervated by vagal efferents and, in addition, displays spontaneous mechanical activity. The preparation thus appears to contain at least two discrete excitable components, the cholinergic neural elements and the smooth muscle membrane. Indomethacin (INDO), a cyclooxygenase (CO) inhibitor, exerts a considerable potentiation of function in this preparation. The latter may be effected indirectly, through loss of the inhibitory effect of endogenous prostaglandin E2 (PGE2) on neural acetylcholine release and through direct effects on smooth muscle of the generally a...
Butcher MT, Bertram JE, Syme DA, Hermanson JW, Chase PB.The digital flexors of horses must produce high force to support the body weight during running, and a need for these muscles to generate power is likely limited during locomotion over level ground. Measurements of power output from horse muscle fibers close to physiological temperatures, and when cyclic strain is imposed, will help to better understand the in vivo performance of the muscles as power absorbers and generators. Skinned fibers from the deep (DDF) and superficial (SDF) digital flexors, and the soleus (SOL) underwent sinusoidal oscillations in length over a range of frequencies (0....
Bowman SG, Marshall JF, Blikslager AT.To determine demographic characteristics of horses donated to the North Carolina State University Equine Health Center (EHC) between 1996 and 2008. Methods: Retrospective cohort study. Methods: 122 horses donated to the EHC between January 1996 and December 2008, and 246 horses offered for donation to the EHC between January 2007 and December 2008. Methods: Telephone and medical records were examined. Data were collected in 5 categories: age, sex, breed, reason for donation, and use prior to donation. Results: From January 1996 through December 2008, 122 horses were donated to the EHC (median,...
Dik KJ.Common soft tissue disorders of the equine carpus are fluctuating or firm soft tissue swellings, wounds and draining tracts. Survey radiography may show the size, position and origin of the swellings and reveals soft tissue calcification, accumulation of air and radiopaque foreign material. Contrast radiography enables accurate visualization of the size, shape, position and origin of fluctuating soft tissue swellings, demonstrates abnormal intersynovial communication and allows precise demonstration of the extent of puncture wounds and draining tracts. Ultrasonography allows differentiation be...
