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Topic:Musculoskeletal System
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.
Solitary osteochondroma of the radius in three horses. Osteochondroma of the distal portion of the radius was diagnosed in 3 horses with a history of lameness and distention of the common tendon sheath of the superficial and deep digital flexor tendons at the level of the carpal canal. In 2 horses, the exostosis was removed through an incision at the caudal border of the lateral digital extensor muscle above the carpal ligament.
The gait of pacers. 1: kinematics of the racing stride. Standardbred pacers have been studied under race conditions to describe the gait of the pacer, and to determine relationships between stage of the race, finish order and selected gait kinematics. Overlap increased with the stage of the race while pacing speed decreased marginally for low order pacers and increased for high order finishers. High order finishing pacers appear to have greater stance and stride lengths than do low order finishers. Pacers could be separated into low order and high order groups on the basis of their movement patterns. High order pacers exhibited greater ranges of li...
Arthrodesis of the equine distal tarsal joints by perforated stainless steel cylinders. Perforated stainless steel cylinders filled with autogenous cancellous bone were implanted in the distal tarsal joints of four horses. Graft cell survival was poor two weeks after surgery in one horse. In two horses, at 10 months there was partial arthrodesis of the joints with incorporation of the implants into the osseous union. The implants were filled with vascularised woven bone. These two horses were sound nine months after surgery. One horse fractured its third tarsal bone and was still positive to a hock flexion test 12 months after surgery.
Non-invasive measurement of bone: a review of clinical and research applications in the horse. The current methods for non-invasive measurement of bone quality are reviewed. In the horse this has traditionally involved the use of radiography, but there are now two other modalities available for the critical evaluation of cortical bone quality and strength. These utilise single photon absorptiometry and ultrasound velocity. Photon absorptiometry gives a direct measurement of bone mineral content, by using a monoenergetic radionuclide source, and transverse ultrasound velocity in bone gives a measure of bone stiffness or elasticity. They can both be used conveniently on the metacarpus of ...
Ultrasonic transmission velocity and single photon absorptiometric measurement of metacarpal bone strength: an in vitro study in the horse. Ten pairs of third metacarpal bones from Thoroughbred horses aged two to 12 years were used to estimate bone strength. Measurements of transverse cortical ultrasound velocity, cortical cross sectional area and bone mineral content were made using ultrasonic transmission velocity and single photon absorptiometry. These data were used to determine bone mineral density, compact bone density and modulus of elasticity. The results were compared with those measured by direct means or chemical analysis and satisfactory correlations were obtained between estimated and measured values. Single photon ab...
Kinematic analysis of the instant centers of rotation of the equine metacarpophalangeal joint. A kinematic analysis of the instant centers of rotation analysis was performed on 21 metacarpophalangeal joints from 11 horses. Manual and computerized methods were used to locate the instant center of rotation on photocopies of transparent composite tracings of a series of radiographs of each joint. The instant centers of rotation of the proximal phalanx about the distal portion of the third metacarpal bone were located consistently on or near the eminence for attachment of the collateral ligaments. The instant centers of rotation of the sesamoids about the distal portion of the third metacar...
Cruciate and collateral ligament failure in the equine stifle: seven cases (1975-1985). Medical records of 7 adult horses with single or multiple ligament failure of the femorotibial ligaments were reviewed to evaluate signalment, history, diagnostic and treatment methods, outcome, and long-term follow-up information. Acute onset of lameness was recorded for most of the horses. Horses with multiple ligament injury had more severe clinical signs than did horses with single ligament injury. Horses with single ligament injury generally required manipulative tests to localize the lameness to the stifle. In all horses, radiography of the stifle assisted in the diagnosis. Horses either...
Speed, stride frequency and energy cost per stride: how do they change with body size and gait? In this study we investigate how speed and stride frequency change with body size. We use this information to define 'equivalent speeds' for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a...
Evaluation of equine locomotion during different degrees of experimentally induced lameness. II: Distribution of ground reaction force patterns of the concurrently loaded limbs. Force plate and high-speed film data from a group of six walking horses were used to study the distribution of the ground reaction forces (GRF) of the concurrently loaded limbs. Three different degrees of supporting lameness were induced in a forelimb or a hindlimb using modified horse shoes. In all experiments the alterations in the distribution in the transverse horizontal GRF (Fx) were small. During unilateral forelimb lameness, the decreased longitudinal horizontal GRF (Fy) was compensated by an increase of the Fy forces of the contralateral forelimb and the ipsilateral hindlimb. The decre...
Monitoring the effects of treadmill exercise on bone by non-invasive means during a progressive fitness programme. Six Standardbred horses underwent a 14-week training programme on a treadmill. The training schedule consisted of five weeks of slow work of six to 12 km/day at 5 m/sec. This was followed by a nine week interval programme increasing in its intensity so that for the last three weeks the horses did three to four intervals/day from 600 to 1000 m at or above maximum heart rate. Ultrasound velocity through the third metacarpus showed a significant increase as a result of training. There was also a significant increase in modulus of elasticity, but no change in bone mineral content, bone mineral den...
Clinical, radiographic, and scintigraphic findings associated with enthesitis of the lateral collateral ligaments of the tarsocrural joint in standardbred racehorses. Injury of the lateral collateral ligaments of the tarsocrural joints was diagnosed in nine Standardbred pacers. The average age was 4.9 years. The severity of the lameness varied from severe to subtle and joint effusion was seen in eight of 10 tarsocrural joints. A positive hindlimb flexion test was seen in four of six cases in which results were recorded. The identification of the site of involvement was based on a focal intense 'hot spot' seen on scintigraphy, and new bone formation seen radiographically at the anatomical sites of insertion of the long lateral collateral ligament of the tars...
Atypical myoglobinuria: an acute myopathy in grazing horses. Four out of 12 horses grazing a field in Berkshire, England, suffered a prostrating illness and died within 12 to 72 h. Serum biochemical abnormalities, including markedly elevated muscle enzymes, were demonstrated and at post mortem widespread myodegeneration was found in both skeletal muscle and myocardium. Urine analysis revealed myoglobinuria, and renal changes were seen histologically. Although similar pathologically, the clinical syndrome and circumstances of the outbreak were not typical of equine exertional rhabdomyolysis (EER). The outbreak bore a striking resemblance to other reporte...
Curettage of subchondral bone cysts in medial femoral condyles of the horse. Fifty-one horses and unilateral or bilateral femorotibial arthrotomy with medial condyle bone cyst curettage. A total of 60 cyst were treated. Treated horses responded to the surgery three to 12 months postoperatively. In 42 horses lameness was reduced or eliminated, enabling them to return to an remain in their intended function. Of these 42 horses 35 are sound, four of which have not started training, and seven showed partial improvement, two of which had no long term follow up. Of the remaining nine horses, two showed no reduction in lameness and seven were not followed up. Arthrotomy was s...
A clinical perspective on lameness originating in the carpus. Clinical experience continues to expand our understanding of the pathophysiology of pain and injury within the carpal joints. The anatomical and physiological capacity of the equine carpus to neutralise loading stress plays a significant role in the prevention of carpal injury. The ability of joint surfaces to dissipate axial force by transfer to the interosseous ligaments is the principal means by which carpal injury is avoided. In the medial aspect of the intercarpal joint and the dorsal aspect of the radial carpal joint, however, the effects of chronic maximal stress and isolated acute supr...
Kinetics and kinematics of the equine hind limb: in vivo tendon strain and joint kinematics. Strains of the suspensory ligament and deep digital flexor, superficial digital flexor, and long digital extensor tendons in the equine (pony) hind limb were recorded in vivo, using implanted strain gauges consisting of silicone rubber tubes filled with mercury. The relationship between strain gauge signals and tendon strains was obtained from tension-strain tests performed on isolated tendons after death of the ponies. During normal walking, maximal tendon strain (elongation over initial length, relative to the length of the structures at first ground contact) was 3.1% in the suspensory ligam...
Equine post anaesthetic myositis: muscular post ischaemic hyperaemia measured by laser Doppler flowmetry. Measurements of muscular microcirculation in horses anaesthetised with halothane were performed by laser Doppler flowmetry. Variations of microcirculation in the compressed and uncompressed triceps brachii were measured when horses were positioned in dorsal recumbency after a prolonged period in lateral recumbency. A significant post ischaemic hyperaemia was recorded in horses which developed a post anaesthetic myositis.
Oxidative capacity of skeletal muscle fibres in racehorses: histochemical versus biochemical analysis. The oxidative capacity of skeletal muscle fibre types was evaluated histochemically using the nicotinamide dinucleotide diaphorase (NADH-D) staining, and biochemically by measuring the activity of citrate synthase (CS) in both whole muscle samples and in pools of fibres of identified type. Duplicate determinations of the NADH-D staining pattern resulted in standard deviations (sd) between duplicates of 6 and 11 per cent for two observers. The NADH-D pattern was found to differ between observers. Duplicate determinations of CS activity in the same fibre pools resulted in an sd value of 2.9 mumo...
Postanesthetic hind limb adductor myopathy in five horses. Five horses that underwent prolonged anesthesia (greater than 3 hours) in dorsal recumbency for a surgical procedure were unable to stand after recovery and were euthanatized. A provisional diagnosis of postanesthetic myopathy was confirmed at necropsy in all 5 horses. However, distribution of affected muscles in these horses was atypical, because there was bilateral hind limb adductor muscle involvement.
Interstitial pH and pressure in the dependent biceps femoris muscle of laterally recumbent anesthetized horses. Interstitial pressure and pH in the dependent biceps femoris muscle were measured in anesthetized, laterally recumbent horses. The mean (+/- standard deviation) interstitial pressure in 10 horses was 19.70 +/- 0.15 mmHg in the 30 to 180 minute interval after induction of anesthesia. Pressures of this order have been associated with reduction in muscle perfusion. Mean (+/- standard deviation) interstitial pH in six horses decreased from 7.07 +/- 0.30 to 6.73 +/- 0.21 between 45 and 150 minutes of anesthesia. These results indicated the presence of circulatory compromise to intracompartmental st...
Neuromuscular and cardiovascular effects of atracurium administered to healthy horses anesthetized with halothane. Neuromuscular and cardiovascular effects of atracurium, a nondepolarizing neuromuscular blocking agent, were evaluated in 10 halothane-anesthetized adult horses. Hind limb digital extensor tension (hoof twitch) was measured with a strain gauge to quantitate the muscle relaxant effects of atracurium. Response of facial muscles was compared with hoof twitch. Five injections of atracurium were given. Initial mean (+/- SEM) dosage of 0.07 +/- 0.01 mg of atracurium/kg of body weight caused 98.6 +/- 0.8% reduction of the preinjection hoof twitch. Subsequent dosages of 0.04 +/- 0.003 mg/kg induced a ...
The similarity of mitochondrial distribution in equine skeletal muscles of differing oxidative capacity. A morphometric analysis was performed on horse muscle tissue to quantify mitochondrial distribution relative to capillaries. Samples of M. vastus medialis, M. semitendinosus, M. masseter and M. cutaneus thoracicus were preserved in a glutaraldehyde fixative for electron microscopy, or frozen for biochemical and histochemical analysis. These four muscles varied from highly oxidative in type, consisting nearly completely of type I fibres, in masseter, to highly glycolytic, primarily type IIb fibres, in cutaneus. In all four muscles, mitochondria were found in highest volume density near capillar...
The influence of supplemental feed on growth and bone development of nursing foals. Thirty foals of mixed breeding, from two consecutive years, were used in two 120-d experiments to evaluate the effects of supplemental feeding (creep feed) on growth in nursing foals. At 10 d postpartum, foals were randomly assigned either to a creep-fed group (CF) or an unsupplemented group (NCF). Initial measurements of body weight (BW), height at the withers (WH), third metatarsal length (MtIII) and third metacarpal length (McIII) were made at 10 d of age and at 30-d intervals thereafter. Medial and lateral cortical peak values for radiographic bone density, cortical width and cortical area...
The arrangement of the muscle layers at the equine ileocaecal junction. The muscle layers of the ileocaecal junctions of horses (n = 18), plains zebras (Equus burchelli antiquorum) (n = 3), mountain zebras (Equus zebra zebra) (n = 2), and a donkey were examined macroscopically and microscopically. The muscular tunic of the ileocaecal papilla was made up of 3 layers: an innermost circular layer which was a continuation of the circular muscle of the ileum, a central longitudinal layer which was a continuation of one part of the longitudinal layer of the ileum and an outermost layer, composed of two collateral semicircular lips, formed by the circular layer of the ca...
Quantification of skin displacement near the carpal, tarsal and fetlock joints of the walking horse. A technique enabling simultaneous visualisation of skin and underlying bony structures in the walking horse was used to quantify skin displacements on the lateral surface of carpal, tarsal and fetlock joints. The technique employed implanted light-emitting-diodes (LEDs) for marking the bone, and self adhesive spot labels for marking the overlying skin. Photographic recordings were made. Skin displacement was measured in six Dutch Warmblood horses. Mean total displacements and mean displacement per degree of change of joint angle were calculated. Displacements at the level of the fetlock joints...
A modified Cloward’s technique for arthrodesis of the normal metacarpophalangeal joint in the horse. A modified Cloward's technique was performed for arthrodesis of one metacarpophalangeal (MCP) joint in eight horses. Dorsal arthrotomies were performed medial and lateral to the common digital extensor tendon and two 16 mm holes were drilled through the joint. A perforated cylindrical stainless steel basket filled with cancellous bone was impacted into each hole. The limbs were supported in casts for 8 weeks. The joints were examined and radiographed at 4 weeks, 8 weeks, 6 months, and 10 months. One horse was euthanatized at week 14 to assess the progress of the arthrodesis. In the other seven...
Distribution of ground reaction forces of the concurrently loaded limbs of the Dutch Warmblood horse at the normal walk. The distribution of the ground reaction forces (GRF) over the concurrently loaded limbs of the normally walking horse was determined from 'representative' GRF patterns of all limbs, which were plotted in correct time order after analysis of simultaneously taken high-speed film. This procedure visualises the GRF patterns of each of the four limbs in relation to the GRF pattern(s) of the one or two concurrently loaded limb(s) during a complete stride. In 15 clinically sound horses the mean averaged GRF data and temporal stride parameters showed an almost complete symmetry between both the foreli...
