The topic of muscle in horses encompasses the study of equine muscle structure, function, and physiology. Muscles in horses are responsible for movement, posture, and various metabolic processes. They are composed of muscle fibers that contract and relax to produce motion and generate force. Research in this area often focuses on muscle development, adaptation to exercise, and the impact of nutrition and training on muscle performance. Conditions such as muscle fatigue, injury, and disorders like equine exertional rhabdomyolysis are also explored. This page compiles peer-reviewed research studies and scholarly articles that investigate the anatomy, physiology, and clinical aspects of muscle in equine species.
Rigby BR, Grandjean PW.To summarize the physical benefits of therapeutic horseback riding and hippotherapy and suggest directions for future research. Methods: Review of databases for peer-reviewed articles related to equine-assisted activities and therapies. Databases included MEDLINE via EBSCO, Web of Science, PubMed, Google Scholar, and Academic Search Complete. Articles were limited to those with full-text access published in English since 1987. Results: Acute and residual improvements in physical benefits, such as gross motor function (e.g., walking, running, jumping), spasticity, muscle symmetry, posture, bala...
LaVigne EK, Jones AK, Londoño AS, Schauer AS, Patterson DF, Nadeau JA, Reed SA.Success as equine athletes requires proper muscle growth in young horses. Muscle hypertrophy occurs through protein synthesis and the contribution of muscle satellite cells, which can be stimulated or inhibited by cytokines and growth factors present during exercise and growth. The hypotheses of this study were that 1) the LM area in young horses would increase over 1 yr, and 2) specific cytokines and growth factors (IL-1β, IL-6, tumor necrosis factor [TNF]-α, IGF-I, and fibroblast growth factor [FGF]-2) would alter proliferation and differentiation of satellite cells isolated from young hor...
Firshman AM, Borgia LA, Valberg SJ.To compare effects of training on conventional and underwater treadmills on fiber properties and metabolic responses of the superficial digital flexor (SDF) and gluteal muscles to high-speed exercise in horses. Methods: 6 unconditioned Quarter Horse-type horses. Methods: 6 horses were walked on underwater and conventional treadmills for 5 d/wk (maximum, 40 min/d) for 8 weeks in a randomized crossover design (60-day detraining period). Horses underwent a standardized exercise test (SET) at high speed before and after training. Analyte concentrations and fiber characteristics were measured in mu...
Hardeman LC, van der Meij BR, Back W, van der Kolk JH, Wijnberg ID.In equine laminitis, the deep digital flexor muscle (DDFM) appears to have increased muscle force, but evidence-based confirmation is lacking. Objective: The purpose of this study was to test if the DDFM of laminitic equines has an increased muscle force detectable by needle electromyography interference pattern analysis (IPA). Methods: The control group included six Royal Dutch Sport horses, three Shetland ponies and one Welsh pony [10 healthy, sound adults weighing 411 ± 217 kg (mean ± SD) and aged 10 ± 5 years]. The laminitic group included three Royal Dutch Sport horses, one Friesian, o...
Do KT, Cho HW, Badrinath N, Park JW, Choi JY, Chung YH, Lee HK, Song KD, Cho BW.Since ancient days, domestic horses have been closely associated with human civilization. Today, horse racing is an important industry. Various genes involved in energy production and muscle contraction are differentially regulated during a race. Among them, creatine kinase (CK) is well known for its regulation of energy preservation in animal cells. CK is an iso-enzyme, encoded by different genes and expressed in skeletal muscle, heart, brain and leucocytes. We confirmed that the expression of CK-M significantly increased in the blood after a 30 minute exercise period, while no considerable c...
Matusovsky OS, Kachmar L, Ijpma G, Bates G, Zitouni N, Benedetti A, Lavoie JP, Lauzon AM.Heaves is a naturally occurring equine disease that shares many similarities with human asthma, including reversible antigen-induced bronchoconstriction, airway inflammation, and remodeling. The purpose of this study was to determine whether the trachealis muscle is mechanically representative of the peripheral airway smooth muscle (ASM) in an equine model of asthma. Tracheal and peripheral ASM of heaves-affected horses under exacerbation, or under clinical remission of the disease, and control horses were dissected and freed of epithelium to measure unloaded shortening velocity (Vmax), stress...
Grimmer NM, Gimbar RP, Bursua A, Patel M.The literature regarding rhabdomyolysis secondary to illicit drug use is sparse. Clenbuterol is a bronchodilator approved for veterinary use, which in high doses can increase protein deposition and lipolysis similarly to anabolic steroids, and is thereby abused for bodybuilding and weight loss effects. Clenbuterol has previously been described in case reports to be cardiotoxic, with patient presentations similar to overdoses of sympathomimetic substances, but reports of rhabdomyolysis are limited to a single case series in horses. Methods: We report the first case of rhabdomyolysis secondary t...
Aleman M, Shapiro K, Sisó S, Williams DC, Rejmanek D, Aguilar B, Conrad PA.Recent reports of Sarcocystis fayeri-induced toxicity in people consuming horse meat warrant investigation on the prevalence and molecular characterization of Sarcocystis spp. infection in horses. Sarcocysts in skeletal muscle of horses have been commonly regarded as an incidental finding. In this study, we investigated the prevalence of sarcocysts in skeletal muscle of horses with neuromuscular disease. Our findings indicated that S. fayeri infection was common in young mature horses with neuromuscular disease and could be associated with myopathic and neurogenic processes. The number of in...
Valberg SJ, McKenzie EC, Eyrich LV, Shivers J, Barnes NE, Finno CJ.Although exertional rhabdomyolysis (ER) is common in Arabian horses, there are no dedicated studies describing histopathological characteristics of muscle from Arabian horses with ER. Objective: To prospectively identify distinctive histopathological features of muscle from Arabian endurance horses with a history of ER (pro-ER) and to retrospectively determine their prevalence in archived samples from Arabian horses with exertional myopathies (retro-ER). Methods: Prospective and retrospective histopathological description. Methods: Middle gluteal muscle biopsies obtained from Arabian controls ...
Carraro U, Kern H, Gava P, Hofer C, Loefler S, Gargiulo P, Mosole S, Zampieri S, Gobbo V, Ravara B, Piccione F, Marcante A, Baba A, Schils S, Pond A....There is something in our genome that dictates life expectancy and there is nothing that can be done to avoid this; indeed, there is not yet any record of a person who has cheated death. Our physical prowess can vacillate substantially in our lifetime according to our activity levels and nutritional status and we may fight aging, but we will inevitably lose. We have presented strong evidence that the atrophy which accompanies aging is to some extent caused by loss of innervation. We compared muscle biopsies of sedentary seniors to those of life long active seniors, and show that these groups i...
Chalmers HJ, Caswell J, Perkins J, Goodwin D, Viel L, Ducharme NG, Piercy RJ.A unilateral neurectomy model was used to study the relationship between histologic and ultrasonographic tissue characteristics during muscle atrophy over time. Methods: This investigation was an in vivo experimental study in an equine model (n = 28). Mean pixel intensity of ultrasonographic images was measured, a muscle appearance grade was assigned weekly, and muscles were harvested from 4 to 32 weeks. Minimum fiber diameter, fiber density per unit area, percent collagen, percent fat, and fiber type profile were measured from muscle cryosections and correlated with the ultrasonographic param...
Houben R, Leleu C, Fraipont A, Serteyn D, Votion DM.This prospective cohort study evaluated the potential of high-resolution respirometry applied to permeabilized muscle fibers for fitness evaluation in French Standardbred racehorses. Fitness evaluation by means of respirometric parameters did not correlate with racing performance registered over the following racing season. However, altered mitochondrial energy metabolism was associated with higher risk of developing exertional rhabdomyolysis, a common cause of exercise intolerance in racehorses. These data represent a first step towards establishing reference values for muscle OXPHOS capacity...
Chintapalli SV, Bhardwaj G, Patel R, Shah N, Patterson RL, van Rossum DB, Anishkin A, Adams SH.The mechanism(s) by which fatty acids are sequestered and transported in muscle have not been fully elucidated. A potential key player in this process is the protein myoglobin (Mb). Indeed, there is a catalogue of empirical evidence supporting direct interaction of globins with fatty acid metabolites; however, the binding pocket and regulation of the interaction remains to be established. In this study, we employed a computational strategy to elucidate the structural determinants of fatty acids (palmitic & oleic acid) binding to Mb. Sequence analysis and docking simulations with a horse (E...
Belaunzaran X, Bessa RJ, Lavín P, Mantecón AR, Kramer JK, Aldai N.The consumption of horse-meat is currently not popular in most countries, but because of its availability and recognized nutritional value consumption is slowly increasing in several western European countries based on claims that it could be an alternative red meat. In this review, horse-meat production, trade and supply values have been summarized. In addition, the advantage of horse production is noted because of its lower methane emissions and increased uptake, particularly of n-3 polyunsaturated fatty acids (PUFAs), which is based on its digestive physiology. Of particular interest in thi...
Herd HR, Sula MM, Starkey LA, Panciera RJ, Johnson EM, Snider TA, Holbrook TC.This report describes 2 genetically related paint mares, case Nos. 1 and 2, presented to the Oklahoma State University Boren Veterinary Medical Teaching Hospital for chronic weight loss and abnormal gait, respectively. Notable findings in both cases included marked persistent eosinophilia and multiple intramuscular lateral thoracic masses. Histologic examination of masses revealed eosinophilic, centrally necrotic granulomas and marked eosinophilic myositis. Granulomas in case No. 1 also contained intralesional Sarcocystis sp material, and adjacent muscle fibers contained intact protozoal cysts...
Shin DH, Lee JW, Park JE, Choi IY, Oh HS, Kim HJ, Kim H.Thoroughbred, a relatively recent horse breed, is best known for its use in horse racing. Although myostatin (MSTN) variants have been reported to be highly associated with horse racing performance, the trait is more likely to be polygenic in nature. The purpose of this study was to identify genetic variants strongly associated with racing performance by using estimated breeding value (EBV) for race time as a phenotype. We conducted a two-stage genome-wide association study to search for genetic variants associated with the EBV. In the first stage of genome-wide association study, a relatively...
Chalmers HJ, Viel L, Caswell JL, Ducharme N.To describe the ultrasonographic changes in the cricoarytenoideus dorsalis (CAD) and cricoarytenoideus lateralis (CAL) muscles of horses before and at various times during the 32 weeks after unilateral neurectomy of the right recurrent laryngeal nerve. Methods: 28 healthy Standardbreds. Methods: For each horse, the appearance of the CAD and CAL muscles on the right (neurectomized) and left (control) sides was serially monitored ultrasonographically by percutaneous (CAD and CAL) and transesophageal (CAD) approaches. The ultrasonographic images were assessed to determine the mean pixel intensity...
Radtke CL, Nino-Fong R, Rodriguez-Lecompte JC, Esparza Gonzalez BP, Stryhn H, McD￮ LA.The objectives of this study were to use non-equilibrium gravitational field-flow fractionation (GrFFF), an immunotag-less method of sorting mesenchymal stem cells (MSCs), to sort equine muscle tissue-derived mesenchymal stem cells (MMSCs) and bone marrow-derived mesenchymal stem cells (BMSC) into subpopulations and to carry out assays in order to compare their osteogenic capabilities. Cells from 1 young adult horse were isolated from left semitendinosus muscle tissue and from bone marrow aspirates of the fourth and fifth sternebrae. Aliquots of 800 × 10(3) MSCs from each tissue source were s...
Ravara B, Gobbo V, Carraro U, Gelbmann L, Pribyl J, Schils S.Functional Electrical Stimulation (FES) has been used extensively over several decades to reverse muscle atrophy during rehabilitation for spinal cord injury patients. The benefits of the technology are being expanded into other areas, and FES has been recently utilized for injury rehabilitation and performance enhancement in horses. Six retired horses (age from 10 to 17 yrs) that had been previously used mainly for dressage riding were selected for this study. Clinical evaluation found epaxial muscle spasms in all horses with minimal to no pelvic extension when manually palpated. FES treatmen...
Fintl C, Hudson NP, Handel I, Pearson GT.Slow waves are rhythmic pacemaker currents generated by the gastrointestinal pacemaker cells, the interstitial cells of Cajal, and represent the rate-limiting step for small intestinal smooth muscle contractions. Therefore, factors that affect slow wave activity may also influence contractile activity. It is not known how temperature changes may influence slow wave activity in the horse. This could be of relevance during colic surgery if cooling of exposed intestine resulted in reduced slow wave activity potentially exacerbating post operative ileus. Objective: To evaluate the effect of temper...
Harrison AP, Elbrønd VS, Riis-Olesen K, Bartels EM.Multi-frequency BIA (mfBIA) equipment has been shown to be a non-invasive and reliable method to assess a muscle as a whole or at fibre level. In the equine world this may be the future method of assessment of training condition or of muscle injury. The aim of this study was to test if mfBIA reliably can be used to assess the condition of a horse's muscles in connection with health assessment, injury and both training and re-training. mfBIA measurements was carried out on 10 'hobby' horses and 5 selected cases with known anamnesis. Impedance, resistance, reactance, phase angle, centre frequenc...
Gim JA, Lee S, Kim DS, Jeong KS, Hong CP, Bae JH, Moon JW, Choi YS, Cho BW, Cho HG, Bhak J, Kim HS.With the advent of next-generation sequencing technology, genome-wide maps of DNA methylation are now available. The Thoroughbred horse is bred for racing, while the Jeju horse is a traditional Korean horse bred for racing or food. The methylation profiles of equine organs may provide genomic clues underlying their athletic traits. We have developed a database to elucidate genome-wide DNA methylation patterns of the cerebrum, lung, heart, and skeletal muscle from Thoroughbred and Jeju horses. Using MeDIP-Seq, our database provides information regarding significantly enriched methylated regions...
Chiocchetti R, Giancola F, Mazzoni M, Sorteni C, Romagnoli N, Pietra M.The lower esophageal sphincter (LES) is a specialized, thickened muscle region with a high resting tone mediated by myogenic and neurogenic mechanisms. During swallowing or belching, the LES undergoes strong inhibitory innervation. In the horse, the LES seems to be organized as a "one-way" structure, enabling only the oral-anal progression of food. We characterized the esophageal and gastric pericardial inhibitory and excitatory intramural neurons immunoreactive (IR) for the enzymes neuronal nitric oxide synthase (nNOS) and choline acetyltransferase. Large percentages of myenteric plexus (MP) ...
Brard S, Ricard A.A genome-wide association study was performed to identify single nucleotide polymorphisms (SNPs) associated with jumping performances of warmbloods in France. The 999 horses included in the study for jumping performances were sport horses [mostly Selle Français (68%), Anglo-Arabians (13%) and horses from the other European studbooks]. Horses were genotyped using the Illumina EquineSNP50 BeadChip. Of the 54,602 SNPs available on this chip, 44,424 were retained after quality testing. Phenotypes were obtained by deregressing official breeding values for jumping competitions to use all available ...
Takahashi T, Matsui A, Mukai K, Ohmura H, Hiraga A, Aida H.It is important to know the effects of the inclination of a slope on the activity of each muscle, because training by running on a sloped track is commonly used for Thoroughbred racehorses. The effects of incline (from -6 to +6%) on the forelimbs and hind limbs during walking and trotting on a treadmill were evaluated by an integrated electromyogram (iEMG). The muscle activities in the forelimbs (5 horses) and hind limbs (4 horses) were measured separately. Two stainless steel wires were inserted into each of the brachiocephalicus (Bc), biceps brachii (BB), splenius (Sp), and pectoralis descen...
Van Driessche K, Ducatelle R, Chiers K, Van Coster R, van der Kolk JH.Very few mitochondrial myopathies have been described in horses. Objective: To examine the ultrastructure of muscle mitochondria in equine cases of myopathy of unknown origin. Methods: Biopsies of vastus lateralis of the Musculus quadriceps femoris were taken predominantly immediately post mortem and processed for transmission electron microscopy. As a result, electron micrographs of 90 horses in total were available for analysis comprising 4 control horses, 16 horses suffering from myopathy and 70 otherwise diseased horses. Results: Following a thorough clinical and laboratory work-up, four o...
Reed SA, LaVigne EK, Jones AK, Patterson DF, Schauer AL.With improvements in care, the equine population is living longer, remaining active, and competing at increasingly older ages. Both advancing age and exercise result in increased concentrations of circulating and local cytokines, including IL-1β, IL-6, and tumor necrosis factor-α. Athletic endeavors in the aged horse may further increase the proinflammatory environment in muscle, decreasing the ability to react appropriately to exercise. Poor response to exercise limits the athletic ability of geriatric horses, thus reducing their useful life span and potentially increasing the risk of injur...
Radtke CL, Nino-Fong R, Esparza Gonzalez BP, McD￮ LA.The objective of this study was to validate non-equilibrium gravitational field-flow fractionation (GrFFF), an immunotag-less method of sorting mesenchymal stem cells (MSCs) into subpopulations, for use with MSCs derived from equine muscle tissue, periosteal tissue, bone marrow, and adipose tissue. Cells were collected from 6 young, adult horses, postmortem. Cells were isolated from left semitendinosus muscle tissue, periosteal tissue from the distomedial aspect of the right tibia, bone marrow aspirates from the fourth and fifth sternebrae, and left supragluteal subcutaneous adipose tissue. Al...
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....
Meng S, Zhang Y, Lv S, Zhang Z, Liu X, Jiang L.With their enormous muscle mass and athletic ability, horses are well-positioned as model organisms for understanding muscle metabolism. There are two different types of horse breeds-Guanzhong (GZ) horses, an athletic breed with a larger body height (~148.7 cm), and the Ningqiang pony (NQ) horses, a lower height breed generally used for ornamental purposes-both inhabited in the same region of China with obvious differences in muscle content. The main objective of this study was to evaluate the breed-specific mechanisms controlling muscle metabolism. In this study, we observed muscle glycogen, ...
Sewell DA, Harris RC.Adenine nucleotide (AN) degradation has been shown to occur during intense exercise in the horse and in man, at or close to the point of fatigue. The aim of the study was to compare the concentrations of muscle inosine 5'-monophosphate (IMP) and plasma ammonia (NH3) during intense exercise with the concentrations of muscle and blood lactate. Seven trained thoroughbred horses were used in the study. Each exercised on a treadmill for periods of between 30 s and 150 s, at 11 and/or 12 m.s-1. Blood and muscle samples were taken and analysed for lactate and NH3 and adenosine 5'-triphosphate (ATP), ...
Nieto JE, Snyder JR, Kollias-Baker C, Stanley S.To determine effects of cisapride and 5-hydroxytryptamine (5-HT) on the jejunum of horses. Methods: Jejunal muscle strips from 8 horses. Methods: Muscle strips were suspended in isolated muscle baths. Isometric stress responses to 5-HT and cisapride, with and without specific antagonists, were determined. Results: Muscle strips incubated with atropine and tetrodotoxin responded to 5-HT and cisapride with an increase in contractile force. The 5-HT caused a concentration-dependent increase in contractile amplitude, with a maximum response (Emax) of 1,151+/-214 g/cm2 and a molar concentration tha...
Rietbroek NJ, Dingboom EG, Joosten BJ, Eizema K, Everts ME.To investigate whether training for show jumping that is commenced early after birth affects the characteristics of equine locomotory muscle. Methods: 19 Dutch Warmblood horses. Methods: Horses were assigned to a trained or not trained (control) group. After weaning, training (free jumping [2 d/wk] that was alternated with a 20-minute period of exercise in a mechanical rotating walker [3 d/wk]) was started and continued until horses were 3 years old. Fiber type composition (determined from myosin heavy chain [MyHC] content), fiber area, diffusion index (area supplied by 1 capillary), citrate s...
Rose RJ, Hodgson DR, Kelso TB, McCutcheon LJ, Bayly WM, Gollnick PD.Changes in blood gases, ions, lactate, pH, hemoglobin, blood temperature, total body metabolism, and muscle metabolites were measured before and during exercise (except muscle), at fatigue, and during recovery in normal and acetazolamide-treated horses to test the hypothesis that an acetazolamide-induced acidosis would compromise the metabolism of the horse exercising at maximal O2 uptake. Acetazolamide-treated horses had a 13-mmol/l base deficit at rest, higher arterial Po2 at rest and during exercise, higher arterial and mixed venous Pco2 during exercise, and a 48-s reduction in run time. Ar...
Gingold BM, Killos MB, Griffith E, Posner L.Maintaining adequate muscle tissue oxygenation is of paramount importance during equine general anesthesia. The objectives of this study were to assess the feasibility, reliability and repeatability of near-infrared spectroscopy (NIRS) muscle oximetry using the Inspectra m650 in conscious healthy adult horses. Methods: Prospective, observational study. Methods: A group of 30 healthy client-owned adult horses admitted to the equine hospital between July 2017 and July 2018. Methods: The probe of an Inspectra m650 NIRS tissue oximeter was placed on the hairless surface of five muscle sites (omotr...
Hodgson DR, Rose RJ, Dimauro J, Allen JR.Biopsy samples were obtained from the middle gluteal muscle of 10 Thoroughbred horses undergoing a commercial race-training program. Samples were obtained before the program began and again after 6 and 12 weeks of training. All horses had raced at least once by the 12th week of training. Serial sections of muscle were examined histochemically for myosin adenosinetriphosphatase after either acid (pH 4.3 and 4.6) or alkaline (pH 10.3) preincubation, and then muscle fibers were identified as types I, IIA, IIB, or IIC. The oxidative capacity of individual fibers was assessed, using the reduced nic...
Harrison GD, Duncan ID, Clayton MK.The age of onset of equine recurrent laryngeal neuropathy has not been ascertained, although the clinical condition of left laryngeal hemiplegia ("roaring") has been recognized for centuries. The purpose of this study was to evaluate the laryngeal muscles of draft horse foals for the presence of fiber-type grouping, indicating denervation and reinnervation, and to determine if histological evidence of recurrent laryngeal neuropathy was present. Abductor and adductor laryngeal muscles from the left and right sides were collected immediately after euthanasia from male draft horse foals, six less...
Andrews FM, Geiser DR, White SL, Williamson LH, Maykuth PL, Green EM.Haematological and biochemical changes in horses competing in the Endurance Test (Phase T and D) of an advanced Horse Trial (HT, n = 22) and the Endurance Test (Phases A-D) of an advanced (CCI) 3-day-event (TD, n = 11) over a similar course on the same day were studied. Environmental conditions during the event were cool (5.5-11.1 degrees C). Blood samples were collected from the horses in each group the evening prior to the Endurance Test, within 60 s after, and 10 min after, completion of Phase D (cross-country jumping). The following were determined in the blood samples and compared between...
Bröjer J, Holm S, Jonasson R, Hedenström U, Essén-Gustavsson B.The degradation of glycogen and its two forms, proglycogen (PG) and macroglycogen (MG) has been studied in horses performing different types of exercise, but no information is available about the resynthesis of PG and MG after exercise. Objective: To determine the resynthesis of PG and MG in skeletal muscle after intermittent uphill exercise. Methods: At a training camp 9 well-trained Standardbred trotters performed a training session comprising a warm-up period, 7 repeated 500 m bouts of exercise on an uphill slope and a recovery period. Muscle biopsies (m. gluteus medius) for analysis of PG,...
Marques C, da Silva B, Nogueira Y, Bezerra T, Tavares A, Borges-Silva W, Gondim L.The protozoan (syn. ) infects horses and has dogs as definitive hosts. Herein we aimed to detect in Brazilian horses destined for human consumption and to determine the frequency of infection in the examined animals. Muscle fragments from 51 horses were collected in a slaughterhouse in Bahia State during three different seasons of the year. Samples from six tissues from each animal were prepared for macroscopic and microscopic evaluation, using tissue grinding, squash and histology. sp. was observed in 100% of the examined horses. Selected samples were processed for transmission electron mi...
Dranchak PK, Leiper FC, Valberg SJ, Piercy RJ, Carling D, McCue ME, Mickelson JR.To evaluate whether biochemical or genetic alterations in AMP-activated protein kinase (AMPK) play a role in the development of polysaccharide storage myopathy (PSSM) in Quarter Horses. Methods: 30 PSSM-affected and 30 unaffected (control) Quarter Horses. Methods: By use of an established peptide phosphotransfer assay, basal and maximal AMPK activities were measured in muscle biopsy samples obtained from 6 PSSM-affected and 6 control horses. In 24 PSSM-affected and 24 control horses, microsatellite markers identified from the chromosomal locations of all 7 AMPK subunit genes were genotyped wit...
Khan FA, Chenier TS, Murrant CL, Foster RA, Hewson J, Scholtz EL.Nitric oxide (NO) may have a role in persistent breeding-induced endometritis in mares through an inhibitory effect on uterine contractility. The objectives of this study were to test the effect of NO on spontaneous uterine contractility in-vitro and to evaluate whether this effect varied between the longitudinal and circular muscle layers of the uterus. Reproductive tracts were collected from eight euthanized non-pregnant mares (age 4-19 years; body weight 405-530 kg). Transrectal examination of the reproductive tract was performed before euthanasia to evaluate stage of the estrous cycle and...
Caple IW, Edwards SJ, Forsyth WM, Whiteley P, Selth RH, Fulton LJ.The activity of glutathione peroxidase, a selenium containing enzyme, was measured in the blood of horses to determine its usefulness as an indicator of selenium status. In 15 horses the enzyme activity was positively related to the blood selenium concentration (P less than .001, r-0.98) over the range of enzyme activities of 8.2 to 140 units (mumoles NADP-oxidised/min/gHb) and selenium concentrations of 0.24 to 2.74 mumol/l. In a group of 8 horses which 2 foals had died with lesions of muscular dystrophy the enzyme activity increased from a mean of 11.8 units before treatment with selenium to...
Menozzi A, Pozzoli C, Zullian C, Poli E, Serventi P, Bertini S.The effects of preferential µ (morphine), selective µ (fentanyl), selective κ (compound U69593) opioid receptor agonists, and nonselective (naloxone) and selective µ (naloxonazine) antagonists on equine small intestinal motility were evaluated in vitro. Samples of circular muscle from equine jejunum were placed in isolated organ baths and drug-induced modifications of both spontaneous and electrically evoked contractile activity were measured. None of the opioid agonists induced a significant change in spontaneous contractions. Fentanyl and U69593 reduced electrically induced contractions,...
Park JW, Kim KH, Kim S, So JR, Cho BW, Song KD.The integration of metabolomics and transcriptomics may elucidate the correlation between the genotypic and phenotypic patterns in organisms. In equine physiology, various metabolite levels vary during exercise, which may be correlated with a modified gene expression pattern of related genes. Integrated metabolomic and transcriptomic studies in horses have not been conducted to date. The objective of this study was to detect the effect of moderate exercise on the metabolomic and transcriptomic levels in horses. In this study, using nuclear magnetic resonance (NMR) spectroscopy, we analyzed the...
Wagner AL, Urschel KL, Betancourt A, Adams AA, Horohov DW.To determine the effects of advanced age on whole-body protein synthesis and activation of the mechanistic target of rapamycin (mTOR) signaling pathway in skeletal muscle of horses. Methods: Six 22- to 26-year-old (aged) and six 7- to 14-year-old (mature) horses. Methods: Whole-body protein synthesis was measured with a 2-hour primed constant infusion of (13)C sodium bicarbonate, followed by a 4-hour primed constant infusion of 1-(13)C phenylalanine. After the infusions, a biopsy specimen was obtained from a gluteus medius muscle and activation of protein kinase B (Akt), p70 riboprotein S6 kin...
Beyer MJ, Freestone JF, Reimer JM, Bernard WV, Rueve ER.Five thoroughbred foals (4 fillies and 1 colt), all in good to excellent body condition, ranging in age from 4 days to 5 weeks at the time of onset of signs, were presented to 2 Kentucky equine hospitals from 1992 through 1996. All 5 foals presented with tachycardia, hyperhidrosis, diarrhea or a recent history of diarrhea, and muscle rigidity or stiff gait. Four of the 5 foals presented for recumbency, seizure-like activity with opisthotonos, or pronounced extensor muscle rigidity. All 5 foals were hypocalcemic. All foals either died or had euthanasia performed. None responded to oral calcium ...
Wijnberg ID, Schrama SE, Elgersma AE, Maree JT, de Cocq P, Back W.Therapeutic options for stringhalt in horses are limited, whereas medical experiences with botulinum toxin type A (Botox) have been positive. To evaluate its effectiveness in horses, surface electromyography (sEMG) signals before and after injection need to be quantified. Objective: Treatment of healthy ponies and cases with Botox should reduce muscle activity in injected muscles and reduce spastic movements without adverse side effects. Methods: Unilaterally, the extensor digitorum longus, extensor digitorum lateralis and lateral vastus muscles of 6 healthy mature Shetland ponies and 2 talent...
Hambleton PL, Slade LM, Hamar DW, Kienholz EW, Lewis LD.Four isocaloric diets containing 4, 8, 12 and 16% dietary fat (as soybean oil) were fed to four horses at four intervals according to a Latin square design. After 3 weeks of conditioning at each interval, diet effects were evaluated by trotting all horses at 3.2 m/sec for 6 hours. Pre- and posttrotting responses were measured in muscle and liver glycogen, serum long-chain fatty acids, serum electrolytes, serum enzymes, serum cholesterol, plasma glucose, packed cell volume and hemoglobin. Dietary fat was highly correlated with exercise-induced plasma glucose changes and with cholesterol concent...
Shaw K, Ursini T, Levine D, Richards J, Adair S.Core strengthening and postural stability are desired outcomes of certain therapeutic exercises performed in horses. This study aimed to quantify changes in muscle activation at a walk and trot in horses traveling over eight consecutive ground poles evenly spaced (at 30 inches for walk and 48 inches for trot) in parallel fashion in a straight line, and with hindquarter and abdominal elastic resistance bands applied at 25% stretch. Surface electromyography (sEMG) data were collected for the longissimus dorsi and rectus abdominus muscles in six horses. A 2 × 2 repeated measures ANOVA was perf...
Latham CM, Dickson EC, Owen RN, Larson CK, White-Springer SH.To test the hypothesis that complexed trace mineral supplementation would increase antioxidant capacity and decrease muscle oxidative stress and damage in young horses entering an exercise training program, Quarter Horses (mean [Formula: see text] SD; 9.7 ± 0.7 mo) balanced by age, sex, and BW were assigned to receive complexed (CTM; n = 8) or inorganic (INORG; n = 8) trace minerals at -12 week relative to this study. Blood and muscle samples were collected before (week 0) and after 12 week of light exercise training surrounding a 1.5-h trailer stressor. Muscle glutathione peroxid...
Edner A, Nyman G, Essén-Gustavsson B.To compare the effects of spontaneous breathing and mechanical ventilation on haemodynamic variables, including muscle and skin perfusion measured with laser Doppler flowmetery, in horses anaesthetized with isoflurane. Methods: Prospective controlled study. Methods: Ten warm-blood trotter horses (five males, five females). Mean mass was 492 kg (range 420-584 kg) and mean age was 5 years (range 4-8 years). Methods: After pre-anaesthetic medication with detomidine (10 microg kg(-1)) anaesthesia was induced with intravenous (IV) guaifenesin and thiopental (4-5 mg kg(-1) IV) and maintained using i...
Hegreberg GA, Reed SM.A progressive neuromuscular disorder in young horses, clinically apparent as early as 1 month of age, is characterized by generalized myotonia, muscle stiffness, muscle weakness and atrophy. Myotonia is identified by percussion dimpling and myotonic EMG discharges. Changes in one case included testicular hypoplasia, cataract formation, and glucose intolerance, indicating a systemic involvement. Pathologic changes in skeletal muscles from three affected foals were examined. Sarcoplasmic masses, ringed fibers, internal positioning of sarcolemmal nuclei, and nuclear rowing were among the primary ...
Lentz LR, Valberg SJ, Mickelson JR, Gallant EM.To determine whether increased sensitivity to pharmacologic agents was a general property of equine exertional myopathies, including polysaccharide storage myopathy (PSSM) in Quarter Horses. Methods: 5 adult Quarter Horses with exertional rhabdomyolysis and abnormal polysaccharide accumulation in skeletal muscle and 4 clinically normal adult Quarter or Quarter-type horses. Methods: Twitch time course measurements and contracture responses to various concentrations of caffeine and halothane for small bundles of intact external intercostal muscle fibers were measured in all horses. Results: Caff...
Gianino GM, Valberg SJ, Perumbakkam S, Henry ML, Gardner K, Penedo C, Finno CJ.Immune-mediated myositis (IMM) in American Quarter Horses (QHs) causes acute muscle atrophy and lymphocytic infiltration of myofibers. Recently, an E321G mutation in a highly conserved region of the myosin heavy chain 1 (MYH1) gene was associated with susceptibility to IMM and nonexertional rhabdomyolysis. Objective: To estimate prevalence of the E321G MYH1 variant in the QH breed and performance subgroups. Methods: Three-hundred seven elite performance QHs and 146 random registered QH controls. Methods: Prospective genetic survey. Elite QHs from barrel racing, cutting, halter, racing, reining...
Ronéus N, Essén-Gustavsson B, Lindholm A, Persson S.Blood samples from the jugular vein and muscle biopsies (gluteus medius) in 25 Standardbred trotters were obtained 5-10 min after racing. The biopsies were analysed for fibre type composition and enzymatic profile and blood samples for plasma lactate and ammonia concentrations. Muscle characteristics, plasma lactate and ammonia concentrations after racing were compared with each horse's individual performance index (IPI). The IPI is calculated annually from the individual horse's racing performance (% placing 1, 2 or 3, total annual earnings, average earning per start, and best racing record),...
Byrne KM, Vierck J, Dodson MV.Equine satellite cells are responsible for muscle healing and regeneration in the mature horse. We describe the in vitro cell culture conditions required for clonal populations of equine satellite cells to undergo both proliferation and differentiation. Our hypothesis is that these in vitro conditions model regeneration of muscle and can be used to evaluate potential therapeutics. In this study, 2 areas of satellite cell response were tested: proliferation of clones induced by growth factors, and fusion induced by culture conditions. Equine satellite cell clones showed differences in their res...
Zhu FX, Zhang XY, Olszewski MA, Robinson NE.The effects of capsaicin and neuropeptides were examined in equine tracheal smooth muscle (TSM). Neither capsaicin nor substance P (SP) contracted TSM. Capsaicin (100 microM) elicited relaxation in TSM contracted with methacholine. This relaxation was not mimicked by SP or calcitonin gene-related peptide (CGRP). Relaxation was not attenuated by removal of the epithelium or by pretreatment of tissue with meclofenamate or the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine. Previous exposure of TSM to capsaicin did not eliminate the relaxation responses to subsequent capsaicin. Although...
Lehnhard RA, McKeever KH, Kearns CF, Beekley MD.There are limited data on age-related changes in body composition or skeletal muscle in the horse. Therefore, the purpose of this study was to investigate any differences in muscle myosin heavy chain (MHC) and body composition associated with aging. Twenty-three young (4-8 years) and eight old (20+ years) unfit Standardbred mares were evaluated. Rump fat thickness was measured using B-mode ultrasound and per cent body fat (% fat) was calculated. Needle muscle biopsies were obtained from right gluteus medius muscle. MHC composition was determined via sodium dodecyl sulphate-polyacrylamide gel e...
