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.
Crook TC, Wilson A, Hodson-Tole E.Locomotion requires successful negotiation of different terrains, but we currently know little of how the musculoskeletal system adapts to cope with positive and negative slopes. Objective: To compare the effects of treadmill speed and gradient on equine hindlimb muscle mean electromyographic (EMG) intensity. Methods: Surface EMG recorded the activity of gluteus medius (GM), biceps femoris (BF), vastus lateralis (VL), gastrocnemius lateralis (GL) and extensor digitorum longus (EDL) in 6 horses at walk (1.4-1.6 m/s) and trot (2.6-3 m/s) on 3 different treadmill gradients (0, 10% and -10%). Sign...
Merritt JS, Davies HM.Bending of the equine metacarpal bones during locomotion is poorly understood. Cantilever bending, in particular, may influence the loading of the metacarpal bones and surrounding structures in unique ways. Objective: We hypothesised that increased amounts of sagittal-plane cantilever bending may govern changes to the shape of the metacarpal bones of Thoroughbred racehorses during training. We hypothesised that this type of bending would require a linear change to occur in the combined second moment of area of the bones for sagittal-plane bending (I) during race training. Methods: Six Thorough...
Zsoldos RR, Kotschwar A, Kotschwar AB, Rodriguez CP, Peham C, Licka T.The rectus abdominis (RA) and oblique external abdominal (OEA) muscles are both part of the construction of the equine trunk and thought to be essential for the function of the spine during locomotion. Although RA activity at trot has previously been investigated, the relationship between OEA and RA at walk and trot has not yet been described. Objective: To document abdominal muscle activities during walk and trot, and test the hypothesis that muscle activity at walk would be smaller than at trot. Methods: Six horses (8-20 years old, 450-700 kg) were used for surface electromyography (EMG) mea...
Addis PR, Lawson SE.The flexor tendons support the metacarpophalangeal (MCP) and distal interphalangeal (DIP) joints during stance phase and since tendon stiffness and strain changes with age, it is likely that kinematics are also age-dependent. Objective: Maximum MCP and DIP angles decrease in the young horse, plateau in the mature horse and increase towards senescence. Methods: The distal limbs of 57 walking horses age 3-212 months were filmed and digitised with an automated tracking system. Maximum MCP and DIP angles during stance phase were used to calculate strain in the superficial and deep digital flexor t...
Wijnberg ID, Sleutjens J, Van Der Kolk JH, Back W.There has been growing interest in training techniques with respect to the head and neck position (HNP) of the equine athlete. Little is known about the influence of HNP on neuromuscular transmission in neck muscles. Objective: To test the hypothesis that different HNPs have effect on single fibre (SF), quantitative electromyographic (QEMG) examination and muscle enzyme activity directly after moderate exercise. Methods: Seven Warmblood horses were studied using a standard exercise protocol in 5 HNPs: HNP1: unrestrained; HNP2: neck raised; bridge of nose around the vertical; HNP4: neck lowered...
Elgersma AE, Wijnberg ID, Sleutjens J, van der Kolk JH, van Weeren PR, Back W.Head and neck positions (HNP) in sport horses are under debate in the equine community, as they could interfere with equine welfare. HNPs have not been quantified objectively and no information is available on their head and neck loading. Objective: To quantify in vivo HNPs in sport horses and develop o a model to estimate loading on the cervical vertebrae in these positions. Methods: Videos were taken of 7 Warmbloods at walk on a straight line in 5 positions, representing all HNPs during Warmblood training and competition. Markers were glued at 5 anatomical landmarks. Two-dimensional angles a...
Hill C, Crook T.Massage is widely used in physiotherapy, but there has been little previous research examining its effectiveness in increasing equine soft tissue length. Objective: To determine the effect of massage on equine hindlimb protraction. We hypothesised that massage to the caudal muscles of the equine hindlimb, specifically the superficial gluteal, semitendinosus, biceps femoris and semimembranosus muscles, can increase passive and active hindlimb protraction. Methods: The study used a crossover design in which 8 horses were randomly assigned to 2 groups of 4, A and B. Group A received massage for 3...
Lawson SE, Marlin DJ.The function of the forelimb is fundamental to understanding both sound and pathological locomotion. The precise movements of the equine shoulder are hidden by layers of skin and muscle and hence the shoulder is normally modelled as a simple pivot during locomotion which assumes that any translational motion is negligible. Objective: To record and quantify the sliding motion of the scapula during locomotion, using a novel imaging technique. Methods: Scapula motion during locomotion in the horse was calculated by tracking the ripple of the shoulder blade's movement under an array of markers pla...
Medica P, Giacoppo E, Fazio E, Aveni F, Pellizzotto R, Ferlazzo A.Trekking is a noncompetitive sport, involving maximal skeletal muscle effort. Exercise and transport may involve significant energy expenditure and give rise to substantial stress. Few studies have examined the combined effect of exercise and additional preliminary transport on adrenocortical and haematochemical responses in horses during trekking. Objective: To ascertain whether exercise and additional preliminary transport before trekking would affect the circulating cortisol levels and haematochemical variables of horses during a 2 day trekking event. Methods: Twenty-nine healthy horses wer...
Warner SM, Koch TO, Pfau T.Assessing back movement is an important part of clinical examination in the horse and objective assessment tools allow for evaluating success of treatment. Objective: Accuracy and consistency of inertial sensor measurements for quantification of back movement and movement symmetry during over ground locomotion were assessed; sensor measurements were compared to optical motion capture (mocap) and consistency of measurements focusing on movement symmetry was measured. Methods: Six nonlame horses were trotted in hand with synchronised mocap and inertial sensor data collection (landmarks: T6, T10,...
Goff L, Van Weeren PR, Jeffcott L, Condie P, McGowan C.Information regarding movement at the ilium and sacrum in nonlame horses during normal gait may assist in understanding the biomechanics of the equine sacroiliac joint. Objective: To determine the amount and direction of motion at the ilium and sacrum using 3D orientation sensors during walk and trot in sound Thoroughbreds. To compare results from sensors fixed to the skin with results from sensors fixed to bone-implanted pins. Methods: Three 3D wireless orientation sensors were mounted to the skin over the tuber sacrale (TS) and sacrum of 6 horses and motion at the ilium and sacrum was record...
Hernlund E, Egenvall A, Roepstorff L.Biomechanical events of the distal limb during the landing phase of a jump have been proposed to be risk factors for injury, indicating need for further characterisation of the landing and the hoof-surface interaction. This is essential also for valid testing of arena surfaces when simulating actual conditions. Objective: To investigate the hoof landing characteristics for different limbs of elite showjumping horses during the landing phase when jumping 1.30-1.50 m competition fences on 2 different arena surfaces. Methods: A single, fixed high speed camera (1000 frames/s) was aimed at landing ...
Latif SN, Von Peinen K, Wiestner T, Bitschnau C, Renk B, Weishaupt MA.To a large extent the success of a racehorse depends on effective and health preserving training methods. An important issue is the prevention of back pain. The influence of different types of training saddles (normal tree: S(A), treeless: S(B), flexible tree: S(C)) on the saddle pressure patterns in racehorses have not previously been investigated. It is commonly assumed that S(A) limits the motion of the back especially in the lower thoracic region during gallop. Objective: S(A) produces higher pressures in the caudal part of the saddle at trot (rising trot), canter and gallop (both in a joc...
de Cocq P, Mooren M, Dortmans A, van Weeren PR, Timmerman M, Muller M, Van Leeuwen JL.In the equestrian world it is assumed that riders use changes in weight distribution and leg forces as important instruments to give horses directions about speed and direction of movement. However, the changes of these forces have never been quantified. Objective: To investigate the distribution of normal forces (perpendicular to surface) underneath the saddle and of normal forces exerted by the rider's legs during lateral movements. Methods: Eleven riders performed 3 different exercises: riding straight ahead, shoulder-in and travers at trot. Three saddle force systems were used simultaneous...
Sloet van Oldruitenborgh-Oosterbaan MM, Genzel W, van Weeren PR.Welfare concerns over the reasons for interruption or termination of a sporting career in horses have been expressed. Objective: To study the career of competition horses and factors that influence career length. Methods: In 2004, 46,576 rider-horse combinations were registered with the Dutch National Equestrian Federation (KNHS) in dressage, show jumping, eventing and endurance. From this population, approximately 1% of horses in each discipline were selected at random and all recorded competition data from the KNHS registration system collected and supplemented by detailed rider/owner teleph...
Barrey E, Bonnamy B, Barrey EJ, Mata X, Chaffaux S, Guerin G.MicroRNAs (miRNA) are small endogenous noncoding interfering RNA molecules (18-25 nucleotides) regarded as major regulators in eukaryotic gene expression. They play a role in developmental timing, cellular differentiation, signalling and apoptosis pathways. Because of the central function of miRNAs in the proliferation and differentiation of the myoblasts demonstrated in mouse and man, it is assumed that they could be present in equine muscles and their expression profile may be related to the muscle status. Objective: To identify miRNA candidates in the muscles of control and affected horses ...
Finno CJ, McKenzie E, Valberg SJ, Pagan J.Recurrent exertional rhabdomyolysis (RER) occurs in fit, nervous Thoroughbreds fed high nonstructural carbohydrate (NSC) diets. Clinical signs are diminished by feeding low NSC, high fat diets; however, the mechanism is unclear. Objective: To determine if the glucose, insulin and cortisol response to isocaloric diets varying in fat and NSC availability differ in fit vs. unfit Thoroughbreds with RER. Methods: Four fit (10 weeks treadmill training) RER Thoroughbred mares were exercised and fed 3 isocaloric (121 MJ/day) diets in a 5 day/diet block design. Two high NSC concentrates, sweet feed (SF...
Godwin EE, Young NJ, Dudhia J, Beamish IC, Smith RK.Mesenchymal stem (progenitor; stromal) cell (MSC) therapy has gained popularity for the treatment of equine tendon injuries but without reports of long-term follow-up. Objective: To evaluate the safety and reinjury rate of racehorses after intralesional MSC injection in a large study of naturally occurring superficial digital flexor tendinopathy and to compare these data with those published for other treatments. Methods: Safety was assessed clinically, ultrasonographically, scintigraphically and histologically in a cohort of treated cases: 141 client-owned treated racehorses followed-up for a...
Selberg K, Werpy N.Ungual cartilage ossification in the forelimb is a common finding in horses. Subtle abnormalities associated with the ungual cartilages can be difficult to identify on radiographs. Magnetic resonance (MR) imaging findings of 22 horses (23 forelimbs) with a fracture of the distal phalanx and ossified ungual cartilage were characterized and graded. All horses had a forelimb fracture. Eleven involved a left forelimb (seven medial; four lateral), and 12 involved a right forelimb (five medial; seven lateral). All fractures were nonarticular, simple in configuration, and nondisplaced. The fractures ...
Suagee JK, Corl BA, Crisman MV, Hulver MW, McCutcheon LJ, Geor RJ.Laminitis is a painful, inflammatory disease of the equine hoof that often results in euthanasia. Elevated plasma insulin concentrations are a predictive factor for laminitis, and in previously healthy horses and ponies, laminitis was induced by infusion of insulin. Thus, we chose to determine if an infusion of insulin would increase plasma concentrations of inflammatory cytokines and cytokine mRNA abundance in subcutaneous adipose tissue, skeletal muscle, and white blood cells. Ten mature Thoroughbred mares received an insulin infusion that elevated plasma insulin concentrations for 6h or an ...
Shmalberg J, Xie H.Acupuncture exerts diffuse analgesic effects through the release of endogenous opioids and other locally and centrally acting mediators. Successful therapeutic interventions for various musculoskeletal conditions in horses are well documented, and acupuncture may significantly enhance performance. The use of acupuncture is specifically supported in treating nonsurgical gastrointestinal disorders, in which specific techniques can alter motility and contribute to visceral analgesia. This article describes the use of acupuncture and Chinese herbal medicine for equine reproductive management and f...
DiMaio Knych HK, Arthur RM, Taylor A, Moeller BC, Stanley SD.Dantrolene is a skeletal muscle relaxant used commonly in performance horses to prevent exertional rhabdomyolysis. The goal of the study reported here was to begin to characterize cytochrome P450-mediated metabolism of dantrolene in the horse and describe the pharmacokinetics of the compound, formulated as a capsule or a compounded paste formulation, following oral administration. Dantrolene is rapidly metabolized to 5-hydroxydantrolene both in vivo and in vitro. Preliminary work with equine liver microsomes suggest that two enzymes are responsible for the metabolism of dantrolene, as evidence...
Dyson SJ, Tranquille CA, Collins SN, Parkin TD, Murray RC.There is little scientific evidence to support the premise that poor foot conformation predisposes to foot pain and lameness. Objective: To determine relationships between external characteristics of the hoof capsule and angles of the distal phalanx; to determine variability in shape of the distal phalanx; and to investigate association between distal phalanx angles and the injury causing lameness. Methods: Feet were documented photographically and radiographically. Linear and angle measurements were obtained for the hoof capsule and distal phalanx and compared statistically. Horses were categ...
Biggi M, Dyson S.Distal border fragments of the navicular bone can be seen in lame and nonlame horses and their clinical significance remains open to debate. Objective: To describe the magnetic resonance imaging (MRI) appearance of distal border fragments and the adjacent navicular bone. To investigate the relationship between fragments and other abnormalities of the navicular bone and the distal sesamoidean impar ligament (DSIL). Methods: Horses were included if pain causing forelimb lameness was localised to the foot and high-field MR images were acquired. The size and location of distal border fragments wer...
Clayton HM, Kaiser LJ, de Pue B, Kaiser L.We compared anteroposterior and mediolateral range of motion and velocity of the center of pressure (COP) on the horse's back between riders without disabilities and riders with cerebral palsy. An electronic pressure mat was used to track COP movements beneath the saddle in 4 riders without disabilities and 4 riders with cerebral palsy. Comparisons between rider groups were made using the Mann-Whitney test (p < .05). The two rider groups differed significantly in anteroposterior range of COP motion, mediolateral range of COP motion, and mediolateral COP velocity. Anteroposterior COP velocit...
Wijnberg ID, Graubner C, Auriemma E, van de Belt AJ, Gerber V.Reference values for quantitative electromyography (QEMG) in neck muscles of Royal Dutch Sport horses are lacking. Objective: Determine normative data on quantitative motor unit action potential (QMUP) analysis of serratus ventralis cervicis (SV) and brachiocephalicus (BC) muscle. Methods: Seven adult normal horses (mean age 9.5 standard deviation [SD] ± 2.3 years, mean height 1.64 SD ± 4.5 cm, and mean rectal temperature 37.6 SD ± 0.3°C). Methods: An observational study on QMUP analysis in 6 segments of each muscle was performed with commercial electromyography equipment. Measurements wer...
Minetti AE, Cisotti C, Mian OS.Although the 3D trajectory of the body centre of mass during ambulation constitutes the 'locomotor signature' at different gaits and speeds for humans and other legged species, no quantitative method for its description has been proposed in the literature so far. By combining the mathematical discoveries of Jean Baptiste Joseph Fourier (1768-1830, analysis of periodic events) and of Jules Antoine Lissajous (1822-1880, parametric equation for closed loops) we designed a method simultaneously capturing the spatial and dynamical features of that 3D trajectory. The motion analysis of walking and r...
Faramarzi B, Cruz AM, Sears WC.To quantify changes in hoof wall strain distribution associated with exercise and time in Standardbreds. Methods: 18 young adult Standardbreds. Methods: 9 horses were exercised 4 d/wk for 30 to 45 minutes at a medium trot for 4 months; 9 nonexercised horses served as the control group. Rosette strain gauges were used to measure the principal surface strains at the toe, lateral quarter of the hoof wall (LQ), and medial quarter of the hoof wall (MQ) of the right forefoot at the beginning and end of the experiment. Midstance maximal (msϵ1) and minimal (msϵ2) principal and peak minimal principal...
Vekens EV, Bergman EH, Vanderperren K, Raes EV, Puchalski SM, Bree HJ, Saunders JH.To provide a detailed computed tomography (CT) reference of the anatomically normal equine stifle joint. Sample-16 hind limbs from 8 equine cadavers; no horses had evidence of orthopedic disease of the stifle joints. Methods: CT of the stifle joint was performed on 8 hind limbs. In all limbs, CT was also performed after intra-articular injection of 60 mL of contrast material (150 mg of iodine/mL) in the lateral and medial compartments of the femorotibial joint and 80 mL of contrast material in the femoropatellar joint (CT arthrography). Reformatted CT images in the transverse, parasagittal, an...
Walker VA, Dyson SJ, Murray RC.Development of core muscle strength is important for training and during rehabilitation following injury. A Pessoa training aid (PTA) is a system of ropes and pulleys which is commonly used during equine training and rehabilitation, but there is limited information on its effectiveness. The objective of the study was to determine the effect of the PTA on the temporal, linear and angular kinematics of the working trot. Influence of testing order on effect of a PTA was assessed in four horses. Twelve riding horses were lunged at working trot on a 16 m diameter circle without (WO) and with a PTA ...
Peat FJ, Kawcak CE, McIlwraith CW, Berk JT, Keenan DP, Selberg KT, Ojeda A.Equine suspensory ligament branch (branch) ultrasonography is becoming increasingly commonplace presale. No ultrasonographical branch reference data exists for Thoroughbred sales horses. Objective: To define the prevalence of ultrasonographical findings in the forelimb suspensory branches of yearling and 2-year-old sales Thoroughbreds and to analyse associations with racing performance. To track changes in branch findings between 1 and 2 years of age in horses that present for sale at both ages. Methods: Prospective cohort study using an enrolled sample. Methods: Horses were enrolled from a ...
Clegg PD, Butson RJ.A nine-year-old Shetland pony gelding, with a history of recurrent upward fixation of the patella, suddenly developed severe lameness in its right hindlimb. A luxation of the coxofemoral joint was diagnosed by a clinical and radiographic examination. The initial treatment of the luxation by closed reduction was not maintained, and the limb was placed in an Ehmer sling for four days after a second closed reduction. This allowed the femoral head to remain in the acetabulum, although a persistent subluxation remained, presumably owing to a rupture of the round ligament. The pony remained comforta...
van den Bogert AJ, Schamhardt HC.Multi-body models of musculoskeletal systems can be used to determine internal forces from measured external forces and movements ('inverse dynamics') and to perform simulations of movements using muscle forces or activations as input ('direct dynamics'). Examples of 'direct' simulations of movements in the horse are presented. With a model of the equine hindlimb, the function of the 'passive stay apparatus' could be explained. A model of the forelimb was used to determine force distributions in the digital flexor tendons, and to experiment with various methods to change the force distribution...
Ikeda Y, Ishihara A, Nakajima M, Yamada K.Thoroughbred racehorses are commonly affected with superficial digital flexor (SDF) tendinopathy. This study aimed to identify risk factors for SDF tendinopathy in racing horses. The authors selected racehorses (n=292) with SDF tendinopathy from the medical records of a racetrack. As a risk factor associated with track-related variables, the SDF tendinopathy odds ratio (OR) was significantly high for a sloppy track surface compared with a standard track surface. Regarding risk factors associated with race-related variables, the SDF tendinopathy OR was significantly high in the following cases:...
Updike SJ, Diesem CD.The vascular supply of the equine stifle joint was investigated, using latex vascular injections of pelvic limbs from 3 adult horses and 6 ponies. Vessels were grossly dissected to the small arteriole level. The primary source of blood supply was the femoral artery and its branches which entered the joint on the caudal and medial surfaces. The superficial vasculature arose from the caudal branch of the deep circumflex iliac artery cranially and laterally, and from the saphenous and descending genicular arteries medially. The deep vasculature arose from the popliteal artery and its branches on ...
Gibson MJ, Bolwell CF, Gee EK, Legg KA, Rogers CW.The objective of this study was to describe the incident and non-incident reports of Thoroughbred flat racing in New Zealand. Retrospective stipendiary stewards' reports of race day events during the 2015/2016 and 2016/2017 racing season were examined. The primary injury and reporting outcomes were analysed to assess the horse- and race-level risk factors associated with the occurrence of incident and non-incident reports. The number of incident and non-incident events and binomial exact 95% confidence intervals were calculated per 1000 horse starts. Most reports were for non-incidents and exa...
Vilar JM, Santana A, Espinosa J, Spinella G.The assessment of a normal range for cross-sectional area (CSA) of tendons in the tarsal region is important in order to use them as reference values in the identification of pathological changes of dimensions. Objective: To provide normal reference values for the CSA of the tendons of the tarsus of Standardbred trotter horses (STH) by means of ultrasonography. Methods: Transverse echographic images of the tendons were obtained at different levels proximodistally; these images were digitised and CSA values (mean ± s.d.) were obtained for each structure. Results: The largest structure correspo...
Sweeney CR, Freeman DE, Sweeney RW, Rubin JL, Maxson AD.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.
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.
Joyce J.Injuries to synovial structures are common in horses and may be life threatening or career ending if severe. Early recognition and initiation of aggressive treatment in the form of appropriate systemic and local antimicrobial therapy and surgical treatment improve the likelihood of a good outcome. Chronic injuries and delayed treatment may result in progression of infection into tendons, bone, and other structures, thus complicating treatment and resulting in a poorer prognosis for return to function.
Williamson AJ, Sims NA, Thomas CDL, Lee PVS, Stevenson MA, Whitton RC.Palmar/plantar osteochondral disease (POD) and third metacarpal/-tarsal condylar fractures are considered fatigue injuries of subchondral bone (SCB) and calcified cartilage due to repetitive high loads in racehorses. In combination with adaptive changes in SCB in response to race training, the accumulation of SCB fatigue is likely to result in changes of joint surface mechanical properties. Objective: To determine the spatial relationship and correlation of calcified articular surface biomechanical properties with SCB microstructure and training history in the distal palmar metacarpal condyle ...
Sharp Y, Tabor G.Links between poor hind hoof balance, pathologies in the hind limb and associated altered posture have been suggested but not quantified. The hoof is proposed as a neuro-sensory organ responsible for informing equine stance with implications for musculoskeletal health in the hind limb and trunk of the horse. This study aims to quantify equine limb posture and its relationship with hoof balance. Twelve horses presenting with negative plantar angles were photographed and limb posture documented before and after the creation of positive plantar angles and improved three-dimensional proportions ar...
Fernandez-Fuente M, Ames EG, Wagner ML, Zhou H, Strom M, Zammit PS, Mickelson JR, Muntoni F, Brown SC, Piercy RJ.To develop a reliable method for converting cultured equine skin-derived fibroblasts into muscle cells. Methods: Equine skin-derived fibroblasts. Methods: The equine myogenic differentiation 1 (eqMyoD) genomic sequence was obtained by use of equine bacterial artificial chromosome screening and PCR sequencing. Total mRNA was extracted from foal skeletal muscle, and eqMyoD cDNA was cloned into a plasmid vector with an internal ribosomal entry site to express bicistronic eqMyoD or enhanced green fluorescent protein (EGFP). Transient expression was confirmed by immunocytochemical analysis and west...
Sack WO.The nerve distribution to the digit of the horse was studied with the compound microscope in serial transverse sections of fetal limbs and plotted on life-size outlines of the horse's foot. It was learned that there is much variation in the topography of the branches of the principal nerves. There is no mirror-image nerve distribution on the 2 sides of the foot. The dorsal branch of the ulnar nerve does not extend below the fetlock. The communication between the palmar metacarpal nerves and branches of the dorsal branch of the digital nerves is only a crossing of nerves without exchange of fib...
Trotter GW, McIlwraith CW, Norrdin RW, Turner AS.Degenerative joint disease of the proximal interphalangeal joint was diagnosed in 9 joint of 6 horses. All of the horses were 3 years old or younger and the affected joints were in the hindlimbs. Radiographic evidence of osteochondrosis involving the distal end of the proximal phalanx was apparent in 5 joints. Lameness and local soft tissue swelling were prominent in all cases. In 1 horse euthanatized tissues because of lameness, histologic examination of joint tissues revealed osteochondrosis as well as severe osteoarthritis. Surgical arthrodesis of the affected joint was performed on 2 horse...
Dube S, Chionuma H, Matoq A, Alshiekh-Nasany R, Abbott L, Poiesz BJ, Dube DK.In order to better understand the training and athletic activity of horses, we must have complete understanding of the isoform diversity of various myofibrillar protein genes like tropomyosin. Tropomyosin (TPM), a coiled-coil dimeric protein, is a component of thin filament in striated muscles. In mammals, four TPM genes (TPM1, TPM2, TPM3, and TPM4) generate a multitude of TPM isoforms via alternate splicing and/or using different promoters. Unfortunately, our knowledge of TPM isoform diversity in the horse is very limited. Hence, we undertook a comprehensive exploratory study of various TPM i...
Cauvin ER, Munroe GA, Boyd JS.This study was undertaken to design a safe technique to examine the carpal flexor tendon sheath (carpal sheath) of horses endoscopically, using an arthroscope. The limbs from 15 horses were used to study the normal anatomy of the carpal sheath and related structures, establish a safe approach and endoscopic technique, and determine the normal endoscopic appearance of the sheath. Major arteries, veins and nerves, present within and around the sheath, left few 'safe' areas to insert the endoscope. Several portals were assessed and a distal lateral approach was found to be safest and to allow ade...
Naylor JM.Hyperkalemic periodic paralysis is an autosomal codominant genetic disease of horses who are descendants of the quarter horse sire Impressive. It produces a muscular phenotype that has been selected by show judges, which has resulted in the rapid dissemination of this disease. Clinical attacks are characterized by muscle fasciculation and spasm, and they respond to treatments for the concurrent hyperkalemia.
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.
Tamura N, Kuroda T, Kotoyori Y, Fukuda K, Nukada T, Kato T, Kuwano A, Kasashima Y.Sonoelastography can assess the inner stiffness of tissues. Sonoelastographic evaluation of injured equine superficial digital flexor tendons (SDFTs) is considered to be useful for assessing the stiffness of a lesion even during late-stage rehabilitation. The purpose of this study was to investigate and compare the sonoelastographic appearance of injured SDFTs over time from the onset of the injury. Eighteen horses were classified into three groups according to the length of time from injury onset: group A, within two weeks after injury; group B, approximately five months after injury; and gro...
Dowling BA, Dart AJ, Hodgson DR, Rose RJ, Walsh WR.To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of healing superficial digital flexor tendon (SDFT) in horses. Methods: Completely randomized design. Methods: Twelve Standardbred horses, 3 to 7 years of age, with ultrasonographically normal forelimb SDFT. Methods: One week after induction of collagenase (2,000 U) induced superficial flexor tendonitis, horses were randomly divided into groups of 6. One group was administered intramuscular rEGH (10 microg/kg/day for 1 week, then 20 microg/kg/day for 5 weeks), whereas the other group (co...
Nielsen BD, O'Connor CI, Rosenstein DS, Schott HC, Clayton HM.The use of weight-training to alter bone strength has not been investigated in horses. Recognising that bone responds to loading, we studied the effect of carrying weight on bone development during training. Seventeen horses were divided into 3 groups: controls exercised counterclockwise in a free-flow exerciser; the weight group performed the same exercise carrying progressively increasing weight up to 45 kg and the weight supplement group also received a myo-anabolic supplement. Radiographic equivalence measure of bone mineral content of zones of the third metacarpi (MCIII) was determined on...
Pozio E, Paterlini F, Pedarra C, Sacchi L, Bugarini R, Goffredo E, Boni P.A total of 120 muscle tissues from three horses naturally infected with Trichinella spiralis were examined. The head was the most infected site. In particular, the muscles harbouring the highest number of larvae were: musculus buccinator (12, 411 and 1183 larvae g-1), the tongue (11, 615 and 1749 larvae g-1), m. levator labii maxillaris (17,582 and 1676 larvae g-1), and the masseter (4.9, 289 and 821 larvae g-1). Compared with the diaphragm, the number of larvae per gram was from 3.5 to 6.8 times higher in the tongue, from 3.5 to 6.5 higher in m. levator labii maxillaris, and from 2.5 to 4.6 h...
Southwood LL, Stashak TS, Kainer RA.To describe the tenoscopic anatomy of the carpal sheath of the flexor tendons (carpal sheath) viewed from a lateral approach. Methods: Tenoscopic observation of structures within the carpal sheath subsequently confirmed by dissection. Methods: 12 equine cadaveric forelimbs. Methods: The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal for the arthroscope was made approximately 3 cm proximal to the distal radial physis and 2.5 cm caudal to the radius between the tendons of the ulnaris lateralis and lateral digital extensor mu...
Stewart B, Reid CF.Osseous cyst-like lesions of the medial femoral condyle were found in 32 horses admitted to the University of Pennsylvania between 1971 and 1978. Sex or breed predilection was not found. In 12 horses, osseous cysts were found in both hindlimbs. Of the 25 horses on which follow-up information was obtained, 16 became sound and useful between 4 months and 1 year after diagnosis. Horses that became lame before 3 years of age had a better chance for later soundness. Horses that became sound had significantly smaller cysts than those that remained lame.
Keg PR, van Weeren PR, Schamhardt HC, Barneveld A.A pressure-sensitive device was developed to measure the force applied to flexion tests of the distal limb of horses. The mean force applied by a group of experienced clinicians was 150 N which results in a moment on the flexed fetlock joint of about 28.5 Nm. The coefficient of variation of the force applied by one experienced clinician was only about 12 per cent, but the coefficient of variation between clinicians was considerably higher (20 per cent), irrespective of whether the clinicians were considered to be experienced or not. The mean force applied by a group of women examiners (114 N) ...
Madill S.Functional alterations within the reproductive system and in other supporting systems may limit the reproductive capacity of geriatric patients; however, the age of onset and degree of compromise show wide individual variation. Aging of the hypothalamopituitary-ovarian axis in the mare manifests as delayed entry to the breeding season, prolonged follicular phases, reduced response to ovulation induction, irregular cycles, oocyte defects, increased early embryonic death, and, eventually, persistent anestrus. Aging of the reproductive tract may increase her susceptibility to endometritis, compro...
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...
