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.
Rose PL, Hightower D, Auer JA, Hulse D, Schenk RK.In the present study, radionuclide scintigraphy and radiography were used to evaluate the rate and degree of healing that occurred in surgically created subchondral bone defects in horses. Following radionuclide scintigraphy and radiography the horses were killed, and histomorphometric analysis was performed on the defect sites. The histomorphometric results were compared to the radionuclide scintigraphic and radiographic results to determine which noninvasive technique provided the most accurate information concerning healing of the bone defects. It was concluded that radionuclide scintigraph...
Koterba AM, Kosch PC.Breathing pattern, respiratory muscle activation pattern, lung volumes and volume-pressure characteristics of the respiratory system of normal, term, neonatal foals on Days 2 and 7 of age were determined to test the hypothesis that the foal actively maintains end-expiratory lung volume (EEV) greater than the relaxation volume of the respiratory system (Vrx) because of a highly compliant chest wall. Breathing pattern was measured in the awake, unsedated foal during quiet breathing in lateral and standing positions. The typical neonatal foal breathing pattern was characterized by a monophasic in...
Frewein J, Buff E.In the anatomical literature there are inconsistencies in the description of the levatores costarum muscles in man and in the domestic animals, and their innervation either by the dorsal or the ventral branches of the thoracic nerves. Therefore we studied the form, structure and, with the aid of the dissecting microscope, the innervation of these muscles in 7 dogs, 8 cats, 5 horses and 12 pigs. In the dog, cat and horse, mm. levatores costarum are present from the second to the last rib. In the pig, these muscles are present from the second to the 15th rib, even in individuals with 16 pairs of...
Firth EC, Greydanus Y.The talus and proximal and distal epiphysis of the humerus, radius, femur, tibia and distal metacarpus of 20 foals aged 0 to 150 days were obtained at necropsy and sawn sagittally into slabs 4 to 8 mm thick. The thickness of the cartilage (articular cartilage and unossified epiphyseal cartilage) was measured in three to five places in each slab, using a sliding calliper. In most epiphyses, the site, or sites, of thickest cartilage was constant in all foals examined. The difference between thickest and thinnest cartilage within one epiphysis was greatest in distal femora and least in distal met...
Duncan ID, Schneider RK, Hammang JP.The suprascapular nerve from 14 horses, which had no clinical evidence of spinatus muscle atrophy, were obtained to determine whether the nerve was sub-clinically compressed at the scapular edge. The nerves were divided into three portions, proximal and distal to the scapular edge and as it reflected around it. In nine horses there was evidence of a chronic neuropathy which varied in severity and which was most severe at the site of reflection, where the nerve appeared constricted by a tendinous band. At this site the predominant change was that of chronic demyelination and remyelination, with...
Deuel NR, Lawrence LM.Bilateral asymmetry in gallop stride limb contact patterns of four Quarter Horse fillies was documented by high-speed cinematography. Horses were filmed with rider by two cameras simultaneously while galloping along a straightaway. Even though signaled for each gallop lead an equivalent number of times, horses frequently switched leads, selecting the left lead nearly twice as often as the right. Velocities and stride lengths were greater for the left lead than the right, but stride frequencies did not differ between leads. Velocity effects were partitioned out in limb contact data analysis to ...
Voorhout G, Klein WR, Meutstege FJ.An avulsion fracture of the tendon of origin of the extensor digitorum longus muscle is reported in a horse and a cat. This avulsion fracture was due to injury in both animals. There was a striking similarity of radiographic findings in these animals, with involvement of the lateral trochlear ridge and lateral condyle of the femur. The horse was slaughtered because of a poor prognosis as a riding-horse. Fixation of the avulsed fragment with two Kirschner wires resulted in complete recovery in the cat.
Schamhardt HC, Merkens HW, Lammertink JL.Software for analysis of force plate recordings of the horse at normal walk is described. The data of a number of stance phases are averaged to obtain a representative tracing of that horse. The amplitudes of a number of characteristic peaks in the force-time curves are used to compare left and right front limbs and left and right hind limbs. The averaged tracings are plotted, default on the line printer or, via separate program, on a high quality pen plotter. A version of the program applicable for analysis of human force plate recordings, is available.
Wright IM.The technique of navicular suspensory desmotomy for the treatment of navicular disease is described and the rationale behind its development is discussed. To date 16 horses involved in a clinical evaluation of the technique have been assessed six months after surgery. Thirteen of these horses are able to work without lameness.
Cahill JI, Goulden BE.This study confirmed that neurogenic muscle pathology exists in intrinsic laryngeal muscles supplied by the recurrent laryngeal nerves in horses subclinically and clinically affected with laryngeal hemiplegia. An important additional observation was the occurrence in three out of four laryngeal hemiplegic horses of neurogenic muscle changes in a hindlimb muscle, the extensor digitorum longus, a muscle supplied by another long peripheral nerve. This finding suggests that a polynenropathy exists in laryngeal hemiplegic horses, and supports the classification of this disease as a distal axonopath...
McClintock SA, Hutchins DR, Brownlow MA.In order to determine optimum tank temperature, nine horses were allocated randomly to three groups and placed in a flotation tank at temperatures of 28 degrees C, 32 degrees C and 36 degrees C. Their progress was monitored by subjective and objective clinical measurements and a variety of laboratory parameters. A 'reacclimatisation crisis' following removal from the tank was observed in most horses after immersion for 21 days and it was concluded that a tank temperature of 36 degrees C provided maximum patient comfort and minimum homoeostatic disturbance.
McClintock SA, Hutchins DR, Laing EA, Brownlow MA.Six adult horses with normal blood gas values, normal thoracic radiographs and free from overt signs of respiratory disease were confined in flotation tanks for periods from one to seven weeks. With one exception, they all coughed, had a variable amount of nasal discharge and, at autopsy, showed cranio-ventral alterations to their lungs which were characterised by patchy irregular areas of absorption atelectasis with or without an inflammatory reaction and an accompanying alveolar emphysema.
Hill T, Carmichael D, Maylin G, Krook L.The incidences of fractures and soft tissue injuries during 68397 starts of thoroughbred horses at New York Racing Association tracks were analyzed concerning track condition, dirt and turf tracks, environmental conditions, length of races, location of fractures on the track, and age of horses. It was concluded that the conditions evaluated are of no importance in the occurrence of racing injuries to thoroughbred horses.
Hardy J, Marcoux M, Eisenberg H.A suspected lesion of osteochondrosis dissecans involving the anconeal process of the humeroradial joint (elbow) was found in 2 horses. In horse 1, the lesion was found during routine lameness examination, during which alleviation of the lameness was achieved after intra-articular anesthesia of the elbow. In horse 2, the lesion was found at necropsy. Horse 1 responded satisfactorily to intra-articular treatment with hyaluronic acid. Both horses also had other joints affected with osteochondrosis dissecans.
White NA, Suarez M.Triceps intracompartmental pressure was measured in the lowermost limb of the recumbent horse during the initial period of recumbency during elective surgical procedures in 11 horses. Intramuscular pressure, using an IM catheter, was measured with the thoracic limbs in 4 different positions, including (I) table-contact limb unadvanced-unsupported free limb, (II) table-contact limb unadvanced-supported free limb, (III) table-contact limb advanced cranially, unsupported free limb, and (IV) table-contact limb advanced cranially, supported free limb. Pressure was measured in the 4 positions with a...
Trotter GW, Auer JA, Arden W, Parks A.Two foals wearing hindlimb casts developed coxofemoral luxations 6 days and 9 days after the casts were applied. One foal had a cast on one hindlimb up to the proximal portion of the tibia and the other foal had tube casts on all 4 limbs. Although the incidents that resulted in the luxations were not observed, they probably occurred during awkward attempts to stand or from being pushed by the mare, with the affected limb being caught under the body in a forward extended and adducted position.
Andrews FM, Spurgeon TL, Reed SM.Skeletal muscle biopsy specimens were taken from 4 male horses with neuromuscular disease such as myotonia congenita, chronic myositis, exertional rhabdomyolysis, and shivers. Histologic and histochemical techniques were used to evaluate skeletal muscle morphologic features and fiber-type population, size, and area, as well as muscle enzyme activities (acid phosphatase, alkaline phosphatase, and esterase). A histochemical and histologic profile were described for each muscle biopsy specimen.
Serteyn D, Mottart E, Michaux C, Micheels J, Philippart C, Lavergne L, Guillon C, Lamy M.Muscular microcirculation was studied in seven halothane anaesthetised horses in lateral recumbency using a laser Doppler flowmeter. A significant difference between the dependent and the uppermost triceps brachii was recorded. In the dependent muscles, microflow at first decreased and then increased up to the starting value. In the uppermost muscles, a significant rise of the microflow was measured.
Leach D, Cymbaluk NF.Velocity-dependent changes in stride length and frequency were studied in 19 male foals, 6 to 8 months of age, and were related to body morphometrics. Eighteen distance and 8 angle measurements were digitized from 16-mm films of standing foals. The total mass and the percentage of total mass acting through the forelimbs were also recorded. Stride length and frequency data were extracted from 16-mm films of 239 strides of the walk, trot, and canter-gallop. Polynomial-regression analysis was used to determine the equation that best described the relationship between data of stride length or freq...
Steiss JE, Naylor JM.A three year old Quarter Horse stallion was presented with a one year history of episodes of generalized muscle tremors and stiffness, and spasm of the muscles of facial expression, lasting 10-15 minutes. Between attacks, the horse was either normal or had a localized muscle tremor in the flank region. Episodes appeared unrelated to exercise. The major abnormal findings included 1) a rise in plasma potassium from a resting level of 4.4 to 7.9 mmol/L during an attack and 2) electromyographic findings of generalized increased insertion activity and myotonic discharges. The horse was treated with...
Yovich JV, Stashak TS, DeBowes RM, Ducharme NG.Fractures of the distal phalanx of the forelimb were diagnosed in 5 colts and 3 fillies ranging in age from 2 weeks to 5 1/2 months at the time of fracture. Three fractures entered the distal interphalangeal joint and 6 fractures (one foal had bilateral fractures) were nonarticular. All foals with articular fractures became sound with conservative treatment. Four of 5 foals with nonarticular fractures became sound with conservative treatment and 1 foal developed separation of the hoof at the coronary band after application of acrylic around the hoof. On the basis of our observations in these f...
Bertone AL, McIlwraith CW, Powers BE, Stashak TS, Aanes WA, Turner AS.Subchondral osseous cystic lesion of the elbow was diagnosed as a cause of lameness in 6 horses. Persistent lameness and signs of degenerative joint disease developed in the first 3 horses treated conservatively with confinement. Subsequently, 3 horses were each treated by extra-articular enucleation of the cystic cavity via the proximal-medial aspect of the radius. Compared with conservative management, better long-term success (determined by return of athletic soundness and less evidence of degenerative joint disease) was achieved with surgical curettage of elbow subchondral cystic lesions.
Cahill JI, Goulden BE, Jolly RD.A detailed investigation of the neuropathology of a horse affected with stringhalt was performed. Qualitative and quantitative light and electron microscopy, and single teased fibre preparations of peripheral nerve demonstrated predominantly axonal degeneration, the stage of which was appropriate for the duration of clinical signs. There was selective involvement of large myelinated nerve fibres. A proximal to distal increase in the severity of pathological changes was present in the peripheral nerves. The long left recurrent laryngeal nerve was the most severely affected, followed in order by...
Moore JN, Mcilwraith CW.Two cases of osteochondrosis are presented. Lesions involving the lateral trochlear ridge of the femur are demonstrated on conventional radiographs and double-contrast arthrograms. A radiographic suggestion of osteochondrosis lesions in the patella is noted. Post mortem examination of one case confirmed the presence of partially free cartilaginous flaps. Reference is made to familial tendency to osteochondrosis in man, dog, pig and horse. The significance of rapid growth rate in the pathogenesis of the condition is also discussed.
Wismann ES, Jacobsen S, Thøfner M, Ladefoged S, Ekstrøm C, Lindegaard C.Outcome after desmotomy of the accessory ligament of the deep digital flexor tendon (AL-DDFT) to treat flexural deformity of the distal interphalangeal joint has been reported to be excellent. However, no studies have compared long-term athletic performance of sport horses exposed to desmotomy of the AL-DDFT to that of matched controls. Objective: The objective of this study is to compare long-term athletic performance in sports horses subjected to desmotomy of the AL-DDFT with the performance of matched controls. Methods: This is an observational multicentre retrospective matched cohort study...
Dewes HF.Fractures of the central tarsal and/or third tarsal bones involving both limbs of six foals are described. Five of the subjects were born either premature or of twin pregnancies. Fractures occurred in the neonatal period and coincided with disablement. Features of behaviour, posture and gait are described, together with gross radiographic findings, bone ash determination and blood chemistry. Lesions observed on the articular faces of tarsal bones recovered from adult horses may have originated during the neonatal-period.
Still J.This case series describes clinical findings in 100 horses displaying pain patterns resembling the anatomical course of the gall bladder meridian. The palpatory pain (tenderness) was detected in individual points, as well as along entire sections of the meridian. A few tender points and areas were also diagnosed outside of the meridian. These data are clinically relevant in terms of the diagnosis and classification of musculoskeletal pain in horses. Therapeutic trials will be reported in a subsequent study.
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.
Haluska GJ, Lowe JE, Currie WB.Recordings of uterine electrical activity were made from 5 pregnant pony mares from Day 141 to 320 of pregnancy. Three types of activity were identified. Short, medium and long bursts were quantified as the percentage of time each occurred during the hour analysed and further categorized according to frequency, amplitude and duration. The uterus was most active during the early stages recorded and became increasingly quiescent after Day 240. Short-burst activity was greatest when the uterus was most quiescent. Long bursts showed the greatest percentage of activity until Day 220 and then decrea...
Harcourt M, Smith C, Bell R, Young A.We describe the radiographic and magnetic resonance imaging findings associated with a case of bilateral forelimb bipartite navicular disease in a 7-year-old Warmblood gelding used for eventing. In addition to the radiographically evident partitioned navicular bones, magnetic resonance imaging (MRI) also detected other concurrent abnormalities occurring within the foot that have not been described before in other cases of navicular bone partition. MRI not only revealed soft tissue lesions of the podotrochlear apparatus, but also allowed for more detailed characterisation of the recently diagno...
Reed SM.The veterinarian needs to be able to incorporate an accurate neurologic examination as a portion of the pre-purchase evaluation. Subtle neurologic deficits may be hidden by musculoskeletal disease or missed as a result of lack of knowledge or understanding of these disorders. It is important to known which musculoskeletal disorders are commonly associated with neurologic disease to better assist the buyer with the decision about whether to purchase the animal.
Sławomirski J, Flieger S, Jastrzebski M, Boratyński Z.The studies carried out on 2 spinal cords of horses showed that cells of the medial motor nucleus (nucleus motorius medialis) are present in all neuromers of the lumbar and sacral segment of the spinal cord. It lies in the medial part of grey matter of the ventral column, neighbouring laterally and ventrally with cells of the lateral motor nucleus, whereas dorsally with cells of the nucleus of the ventral commissural horn. Along the nucleus numerous constrictions and intervals are found, which are connected with various numbers of nerve cells in particular cross-sections.