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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.
Lateral patellar luxation in miniature horses. Bilateral luxation of the patella in four Miniature Horses was corrected by a lateral release incision and medial imbrication of the parapatellar fascia to the tendon of the sartorius muscle. Before surgery, the four horses had a grade 3 to 4 lateral patellar luxation bilaterally and had difficulty walking. Trochlear ridge hypoplasia was evident on radiographs in each horse. Follow-up information varied from 11 months to 4 years after surgery. Three horses had no patellar luxation or lameness. The other horse had a normal right stifle, but patellar luxation (grade 3) had recurred on the left.
Ultrasonographic appearance of ruptured peroneus tertius in a horse. Ultrasonography was a valuable diagnostic tool for examination of a ruptured peroneus tertius in a horse, because it allowed visualization of the extent of the injury and evaluation of healing prior to return of the horse to athletic activity.
Localization of xanthine dehydrogenase mRNA in horse skeletal muscle by in situ hybridization with digoxigenin-labelled probe. In situ hybridization was used to localize xanthine dehydrogenase (XDH) mRNA in horse skeletal muscle. Capillary endothelial cells were found to express XDH, but muscle cells did not give any signal. The digoxigenin-labelled probe was produced by PCR with primers based on the cDNA sequence of mouse XDH and horse lung cDNAs. A 4.3 kb mRNA was detected in a Northern blot.
[3H]ouabain binding in skeletal muscle from horses with hyperkalemic periodic paralysis. Ouabain, a cardiac glycoside, binds to the Na(+)-K(+)-adenosine triphosphatase (Na+ pump) and prevents active transport of Na+ and K+ across cell membranes. We used [3H]ouabain to quantify the number and affinity of Na+ pumps in skeletal muscle from Quarter Horses with the muscular disorder hyperkalemic periodic paralysis (HYPP). [3H]Ouabain-binding properties of gluteal muscle from clinically normal and affected horses were used to determine whether altered Na+ pump number or affinity could contribute to the pathologic features of muscle in affected horses. Foals and adult horses with HYPP we...
Clinical syndrome and diagnosis of hyperkalaemic periodic paralysis in quarter horses. Of the 16 horses studied, 14 belonged to a family previously shown to be susceptible to hyperkalaemic periodic paralysis (HPP), and 8 were shown to have HPP. Diagnosis of HPP by electromyographic detection of myotonic discharges or by oral administration of KCl to induce clinical signs and hyperkalaemia had similar reliability and gave the same result in 80% of cases. KCl had to be administered at doses up to 0.2 g/kg bodyweight to produce signs in some horses. KCl challenge testing was more time consuming than EMG and resulted in one fatality. Overall, electromyography and potassium challenge...
Ground reaction force patterns of Dutch Warmbloods at the canter. Ground reaction force (GRF) patterns from 20 clinically sound Dutch Warmbloods were recorded at the right fore-leading canter, and a standard horse was composed. These GRF data for the standard can be used for evaluation of jumping horses. The GRF patterns were asymmetric for all 4 limbs. The leading right forelimb decelerated the body. The trailing left forelimb propelled the body and decelerated it slightly. The trailing left hind limb propelled, and the leading right hind limb contributed to deceleration and propulsion. Referred to the maximal vertical load of the leading right forelimb, th...
External loads on the limbs of jumping horses at take-off and landing. Using a force plate, ground reaction force (GRF) patterns at take-off and landing between the hooves and the ground were recorded for all limbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the right-leading canter. Distribution of the GRF and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory GRF of the hind limbs were 3 to 5 times higher than at the normal canter, depending on the jumping technique of the horse. At landing, the propulsory GRF were mainly increased in the trailin...
Conservative management of femoral diaphyseal fractures in four foals. Femoral fractures in young horses can occur as a result of severe trauma and generally have a poor prognosis despite treatment. Four young horses with femoral diaphyseal fractures were managed with conservative treatment consisting of prolonged rest, analgesics, hind limb support, and corrective farriery. A favorable outcome in the form of pasture soundness with potential for limited athletic usefulness was obtained in 3 out of the 4 cases. This report supports the use of conservative treatment of selected diaphyseal femoral fractures in young horses.
Ultrasonographic observations of the flexor tendons and ligaments of the metacarpal region of horses. 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...
Hemorrhage into the guttural pouch (auditory tube diverticulum) associated with rupture of the longus capitis muscle in three horses. Three horses were determined to have hemorrhage into a guttural pouch unassociated with mycosis, empyema, neoplasia, or foreign body. The source of the hemorrhage appeared to be the rupture of the longus capitis muscle and its associated vascular supply.
Effect of constant load training on skeletal muscle histochemistry of thoroughbred horses. Skeletal muscle adaptations to training of differing intensities were examined in 10 thoroughbred horses that underwent six weeks of treadmill training followed by six weeks of detraining. The horses were randomly assigned to either a slow group exercised at 40 per cent maximum oxygen uptake (VO2max) or a fast group at 80 per cent VO2max. Resting muscle biopsies were taken before training, after six weeks of training and after six weeks of detraining, from m gluteus medius and m biceps femoris. Muscle was analysed histochemically for fibre type composition (myosin ATPase) and capillary supply ...
Ground reaction force patterns of Dutch warmblood horses at normal trot. This study was undertaken to establish limb loading patterns of sound horses at the trot, to provide a data base against which results for lame horses could be compared. Ground reaction force (GRF) data were collected from 20 clinically sound Dutch Warmblood horses. The data from at least 5 stance phases of each limb were averaged after standardisation to the animal's body mass and to the stance phase duration and resulted in 'representative' GRF data. The symmetry in the vertical GRF peak amplitudes, impulses and the stance phase duration comparing left and right limbs exceeded 97%. By averag...
Arthrodesis of the distal interphalangeal joint in two horses using three parallel 5.5-mm cortical screws. The distal interphalangeal joint was successfully arthrodesed in two horses using three parallel 5.5-mm cortical screws and an autogenous cancellous bone graft. The screws were directed from the palmar proximal border of the second phalanx dorso-distally across the joint space and into the third phalanx. The technique was first developed on a normal horse. The second horse, a clinical case, ruptured its deep digital flexor tendon with complete luxation of the distal interphalangeal joint. Bony fusion of the distal interphalangeal joint occurred in both horses, but both also had residual lamene...
The incidence and severity of intercarpal ligament damage in the equine carpus. The arthroscopic findings in 104 intercarpal joints in 76 horses were reviewed to determine the incidence and severity of changes in the medial intercarpal ligament. Damage to the intercarpal ligament was observed in 43 joints in 35 horses, ranging from mild fraying of the edges of the ligament to complete disruption of all fibres. This represented an incidence of 41% of joints being affected. In 9 joints examined arthroscopically primarily as a further diagnostic procedure, ligament damage was evident in all cases. In horses undergoing arthroscopic surgery primarily for the treatment of osteo...
Effects of short-term cast immobilization on equine articular cartilage. Hexosamine concentration (an index of proteoglycan content), DNA content (an index of cellularity), and [35S]sulfate incorporation (an index of proteoglycan synthesis) of articular cartilage were measured in biopsy specimens from medial proximal sesamoid bone, medial condyle of the third metacarpal bone, and proximal dorsal rim of the proximal phalanx in both metacarpophalangeal joints of 6 adult horses. One limb was then placed in a fiberglass cast that extended down from the proximal portion of the metacarpus and enclosed the hoof; the other limb was not casted. After 30 days of stall confin...
Mechanical implications of collagen fibre orientation in cortical bone of the equine radius. Mechanical test specimens were prepared from the cranial and caudal cortices of radii from eight horses. These were subjected to destructive tests in either tension or compression. The ultimate stress, elastic modulus and energy absorbed to failure were calculated in either mode of loading. Analysis was performed on the specimens following mechanical testing to determine their density, mineral content, mineral density distribution and histological type. A novel technique was applied to sections from each specimen to quantify the predominant collagen fibre orientation of the bone near the plane...
[The laterocranial fascia structures in the upper and forearm and the differences in the insertion of the M. biceps brachii in domestic mammals]. The laterocranial fascia of the upper arm and forearm, as well as aponeurotic relationships of the Musculus biceps brachii were investigated on each of ten forelimbs from horses, cattle and swine. Ten canine biceps were also investigated. Equine and bovine fascia contain elastic components. An as-yet undescribed ligament-like aponeuroses of the laterocranial forearm fascia to the Fossa radialis humeri was seen in all three species studied. The laterocranial fascia of the upper and forearm form a common passage for the Musculi brachialis et extensor carpi radialis. In the case of the horse, the...
Dissipation of metabolic heat in the horse during exercise. Horses were exercised at 40, 65, and 90% of their maximum O2 uptake (VO2max) until moderately fatigued (approximately 38, 15, and 9 min, respectively) to assess heat loss through different routes. Approximately 4,232, 3,195, and 2,333 kcal of heat were generated in response to exercise at these intensities. Of this, approximately 7, 16, and 20% remained as stored heat 30 min postexercise. Respiratory heat loss, estimated from the temperature difference between blood in the pulmonary and carotid arteries and the cardiac output, was estimated to be 30, 19, and 23% of the heat produced during exe...
Skeletal muscle histochemistry in male and female Andalusian and Arabian horses of different ages. Muscle biopsies were taken from the middle gluteal muscle of 143 untrained horses (83 Andalusians [AN] and 60 Arabians [AR]) ranging from 10 days to 24 years old. The horses were separated according to breed and sex and allotted to five age groups: A, 0 to three months; B, yearlings; C, two to three years; D, five to 10 years; and E, 11 to 24 years. There was an increase in the percentage of type I fibres (about 100 per cent) as well as a decrease in the percentage of type IIB fibres (AN, 50 per cent; AR, 40 per cent) over the five age groups. The percentage of type IIA fibres rose significant...
Generalized medullary infarction of the long bones in a horse. Generalized medullary infarction of the long bones was diagnosed in a 12-year-old Tennessee Walking Horse mare. The mare was referred after a 6-week course of shifting weight on her hind limbs, and kicking. Physical examination revealed mild stifle joint distention and withdrawal reactions to digital pressure over the long bones. Radiography revealed patchy areas of medullary sclerosis in the distal portion of each femur and proximal portion of each tibia. A full-thickness cortical and cancellous tibial biopsy revealed infarcted bone marrow, with cortical and periosteal osteonecrosis. The caus...
Pathological analysis of bone fractures in race horses. Pathomorphological analysis was performed on fractured bones of 470 race horses. The most common fracture site was the limb (98% of cases), and the majority of fractures were intra-articular. Focal osteochondral lesions consisting of osteochondrosis, osteonecrosis and osteosclerosis were observed frequently in fractured and non-fractured bones. In the fractured bones, the lesions frequently appeared in the vicinity of the fractured site. Under the influence of antecedent osteochondrosis from the young stage, osteosclerotic and osteonecrotic lesions may have been induced by immoderate exercise ...
Relationship between locomotor forces, hoof position and joint motion during the support phase of the stride of galloping horses. Three methods were used simultaneously to determine the relationships between the vertical forces exerted on the hooves and the positions of the limbs and hooves at the times of peak vertical forces from 2 horses galloping on a track straightaway. Vertical forces were recorded from an instrumented shoe, fetlock joint motion was measured with an electrogoniometer and the angles of the carpus, fetlock and hoof were determined from slow-motion films. At hoof contact, the mean angles of the carpus and fetlock were 181-182 degrees and 199-206 degrees, respectively. Peak vertical forces on the heel ...
Surface strain on the dorsal metacarpus of thoroughbreds at different speeds and gaits. Stacked rectangular rosette strain gages were used to measure surface bone strain on the dorsomedial cortex of the third metacarpal bones in 6 adult Thoroughbred horses during treadmill exercise. The peak principal compressive and tensile strains, angle of the peak strains and strain rate during loading were calculated and compared with speed and gait. At speeds from 4 to 14 m/s loading on the metacarpus resulted in compression of the dorsomedial cortex. Tension only occurred consistently in 1 forelimb of 1 horse at the walk (2 m/s). The angle of peak compression was within 10 degrees of the l...
