The physiology of horses encompasses the study of the biological functions and processes that occur within the equine body. This includes the examination of various systems such as the cardiovascular, respiratory, musculoskeletal, digestive, and nervous systems. Understanding equine physiology is essential for comprehending how horses adapt to different environmental conditions, perform physical activities, and respond to health challenges. Research in this field often focuses on the mechanisms of energy metabolism, thermoregulation, and muscle function during exercise, as well as the physiological responses to stress and disease. This page compiles peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine physiology, providing insights into the biological processes that support the health and performance of horses.
Hallman IAM, Raekallio MR, Karikoski NP.Vatinoxan is a peripherally acting alpha2-adrenoceptor antagonist used in veterinary medicine to attenuate the side effects of alpha2-adrenoceptor agonists. Vatinoxan also increases insulin response and reduces blood glucose (BG) after intravenous glucose in other species. The aim of this study was to investigate the effects of vatinoxan on BG and insulin concentration in horses after intravenous glucose. The design was an assessor-blind cross-over study. Nine horses were assigned to intravenous vatinoxan (0.2 mg/kg; VAT) or saline (SAL). Horses were administered an intravenous glucose bolus (...
Rişvanli A, Şen İ, Canuzakov K, Tulobayev A, Taş A, Salykov R, Ceylan N, Türkçapar Ü, Alimov U, Kazakbayeva A, Cunuşova A, Abdimnap Uulu N....The presented study outlines a research plan aimed at determining the effects of winning and losing situations on the relationship levels between the rider and horse's stress, metabolic, and physiological parameters in Kök-Börü, a traditional equestrian team game. For this purpose, blood samples were collected from both the horses and riders of four different teams participating in two different Kök-Börü games before and after the games. Cortisol, ACTH, beta-endorphin, epinephrine, norepinephrine, T3 and T4 analyses were performed on the collected blood samples using species-specific com...
Aragona F, Rizzo M, Arrigo F, Arfuso F, Fazio F, Giudice E, Pugliatti P, Piccione G, Giannetto C.Among physiological parameters, total locomotor activity (TLA) and heart rate (HR) are used as physiological indicators in animal welfare evaluations. The present study aimed to simultaneously record for 24 h the TLA and HR of ten clinically healthy horses housed in conventional individual boxes subjected to a natural photoperiod and temperature. An actigraphy-based data logger was placed on the headstall, and an equine HR monitor was placed around the chest to monitor TLA and HR, respectively. Activity was monitored with 5 min sampling intervals and HR with 5 s intervals. To make the data poi...
Conrad MB, Leatherwood JL, Paris BL, George JM, Martinez RE, Vergara-Hernandez FB, Nielsen BD, Colbath AC, Arnold CE, Glass KG, Welsh TH, Bradbery AN.Extra-label bisphosphonate (BP) use in juvenile horses is anecdotally reported, primarily for analgesic effects, despite the limited scientific understanding of biologic impacts on skeletally immature horses undergoing exercise. The objective of this study was to determine the effects of clodronate disodium (CD), a form of BP, on endocrine regulators of calcium. Thus, 32 yearling Quarter Horses were stratified by age (500 ± 13 d), body weight (BW; 336 ± 26 kg), sex (n = 16 geldings, n = 16 fillies), and initial bone optical density into 1 of 4 treatment groups for a 168-d tr...
Munsterman AS, Dias Moreira AS, Kottwitz J.To evaluate the effects of detomidine on equine intestinal slow-wave activity and frequency distribution measured by electrointestinography (EIG). Methods: Prospective, experimental study. Methods: University teaching hospital. Methods: A convenience sample of twelve 7- to 21-year-old clinically normal horses. Methods: Horses were randomly assigned to saline control (four horses) or detomidine treatment (eight). After obtaining a 30-min baseline EIG, a saline or detomidine bolus was administered, followed by a constant rate infusion, and another EIG was recorded. Ultrasonographic examinations ...
Abraham AJ, Duvall ES, Doughty CE, Riond B, Ortmann S, Terranova M, le Roux E, Clauss M.The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excreti...
Davie A, Beavers R, Denham J.The purpose of this review was to analyze the scientific background and practical application of a very successful human training methodology, the pyramidal training model, to the Thoroughbred racehorse. Despite years of research and accumulated knowledge on human training methods to enhance endurance performance, Thoroughbred training programs have lacked significant change. This review introduces the pyramidal training model, explains the science that underpins this training concept and outlines one approach to translate this science into the equine field. It also discusses the importance of...
Van den Branden E, Salamone M, Broothaers K, Peere S, Polfliet E, Dewulf M, Van Steenkiste G, van Loon G, Smits K, Govaere J.The use of transvaginal ultrasound-guided follicle aspiration (TVA) for oocyte collection has become a widely used procedure in horses for embryo production (IVEP). The TVA procedure is characterized by various manipulations, which are physical restraint, perineal preparation, transrectal palpation, insertion of an intravaginal device, and needle punctures. These repeated transvaginal and transovarian punctures have raised concerns about their potential effects on mare welfare. Our study aimed to investigate the effects of TVA manipulations, and especially puncturing, on pain and stress in ma...
Hartwig S, Rankovic A, McCrae P, Gagliardi K, Burron S, Ellis J, Ma DWL, Shoveller AK.Behavioural reactivity in horses poses a welfare and safety risk to both the horse and the handler, however, beneficial effects have been observed when dietary fat is increased in replacement of sugar. Supplementation with the fatty acids (FA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) appear to improve negative behaviours in rodents and humans, but the effect of α-linolenic acid (ALA), EPA, and DHA, specifically, on reactivity in horses is unknown. The objective of this study was to evaluate the effects of camelina oil (CAM; ALA-enriched) and a mix of camelina and algal oil (ALG; ...
Science (New York, N.Y.)March 28, 2025
Volume 387, Issue 6741 eadr8589 doi: 10.1126/science.adr8589
Castiglione GM, Chen X, Xu Z, Dbouk NH, Bose AA, Carmona-Berrio D, Chi EE, Zhou L, Boronina TN, Cole RN, Wu S, Liu AD, Liu TD, Lu H, Kalbfleisch T....Horses are among nature's greatest athletes, yet the ancestral molecular adaptations fueling their energy demands are poorly understood. Within a clinically important pathway regulating redox and metabolic homeostasis (NRF2/KEAP1), we discovered an ancient mutation-conserved in all extant equids-that increases mitochondrial respiration while decreasing tissue-damaging oxidative stress. This mutation is a de novo premature opal stop codon in KEAP1 that is translationally recoded into a cysteine through previously unknown mechanisms, producing an R15C mutation in KEAP1 that is more sensitive to ...
Mehrazin H, Sakha M, Safi S.Due to their high specificity and exclusive cardiac myocyte sensitivity, cardiac troponins T and I (cTnT, cTnI) are currently regarded as ideal biomarkers to identify cardiomyocyte damage, myocardial injury, myocardial infarction, and chronic heart failure. In fact, cTnI is considered the most reliable biomarker for diagnosing heart-related issues. This study aimed to investigate the effects of age, gender, and exercise training on serum cTnI levels and various parameters related to the cardiovascular capacity of Caspian horses. For this purpose, 50 adult Caspian horses over 3 years old, both ...
Wang T, Meng J, Wang J, Ren W, Yang X, Adina W, Bao Y, Zeng Y, Yao X.The purpose of this study was to explore the relationship between blood lipid levels and the differences in cardiac structure and function of trained and untrained Yili horses as related to exercise performance. We utilized quantitative lipidomics technology to elucidate how the differences in lipid compounds in the blood influenced performance outcomes. Sixteen 18-month-old Yili horses were selected, ten of which received a 15-week training regimen, and six were kept as untrained controls. Cardiac structure and function were assessed by echocardiography, while plasma lipid metabolites were de...
Edling CE, Arevalo-Turrubiarte M, Premont A, Uribe MC, Forbes B, Kemp V, Weir J, Marr C, Lewis R, Jeevaratnam K.Athlete horses' contraction and conduction of the healthy heart influences racing performance. Gene expression patterns in the horse heart are not yet fully investigated. We aimed to evaluate the gene expression from the four chambers of the heart overall and with focus on genes involved in the electrophysiology of the heart in Thoroughbred racehorses with no clinical cardiac abnormalities. Tissue was collected from the left atrium (LA), right atrium (RA), left ventricle (LV), and right ventricle (RV). Total RNA was analysed by microarray technique. We compared gene expression in the heart cha...
Mota-Rojas D, Whittaker AL, Coria-Avila GA, Martínez-Burnes J, Mora-Medina P, Domínguez-Oliva A, Hernández-Avalos I, Olmos-Hernández A....The growing interest in managing and recognizing pain in animals has led to the search for more sensitive methods to evaluate it, especially because some species conceal any visible changes associated with pain or are not easily assessed. Research has shown that an animal's facial expression changes when exposed to painful stimuli. Thus, developing several pain scales (grimace scales) in species such as horses, cattle, pigs, sheep, donkeys, rabbits, rats, mice, and cats has helped to improve the study of pain in veterinary medicine. The possibility of using facial expression as an indicator of...
Giannetto C, Aragona F, Fazio F, Piccione G, Giudice E, Arfuso F, Zumbo A.This study aimed to examine the impact of climatic conditions on feed intake, body weight, and rectal temperature in horses residing in the hot Summer Mediterranean climate zone. Eight gelding Italian Saddle horses, with an average body weight of 427.78 ± 54.55 kg and aged between 10 and 13 years, participated in the research. All horses were individually housed in a paddock (800 m/horse), and fed ad libitum. Food intake, body weight, and rectal temperature were recorded every 10 days at four 30-day collection periods in the year: January, April, July, and October. The formula adapted fr...
McCarthy RD, Ordóñez HJ, Semevolos SA.To compare core temperatures of superficial and deep digital flexor tendons (SDFT, DDFT) during application of a compression cooling system versus ice boots and during subsequent lower limb bandaging. Methods: Experimental study. Methods: Paired forelimbs of six sedated horses. Methods: Thermocouples were placed in the core of SDFT and DDFT of both front limbs of each horse. A compression cooling system was applied to one front limb and an ice boot was applied to the other front limb for 60 min and then removed for 60 min. Standing bandages were then applied to both front limbs for 60 mi...
Lundblad J, Rhodin M, Hernlund E, Bjarnestig H, Hidén Rudander S, Haubro Andersen P.Facial expressions in prey animals such as equines can convey information regarding their internal state and are therefore often used as cues for welfare and pain evaluation. The state of pain is commonly compared to a neutral state with little consideration given to other experiences that could affect the animal, although this situation is rare outside of experimental contexts. To evaluate the effect of managerial contexts on facial expressions from a nociceptive input, conspecific isolation and sedation with known physiological effects were compared to compound states of nociception. Using a...
Rankins EM, Faremi BE, Hartmann K, Quinn A, Posada-Quintero HF, McKeever KH, Malinowski K.Heart rate variability (HRV) can be measured as an indicator of autonomic nervous system (ANS) balance and thus, stress and affective arousal. Mixed results have been reported in the limited literature addressing the effects of equine-assisted services (EAS) on HRV in the human and horse participants. The aims of the present study were to determine the effects of ground-based adaptive horsemanship (AH) lessons on veterans' and horses' HRV during weekly lessons as well as veterans' resting HRV outside of lessons. Veterans with post-traumatic stress disorder (PTSD) were randomly assigned to 8 w...
Bercovitz GR, Sullivan SN, Reed RA, Ryan CA, Diehl KA.To evaluate the effect of intravenous mannitol and hypertonic saline (HS) on intraocular pressure (IOP) and biometry parameters of horses with elevated intracranial pressure (ICP). Methods: Seven horses with normal ophthalmic exams were anesthetized and placed in lateral recumbency. A subarachnoid transducer was placed, and the head was lowered until ICP measured 40 mmHg +/- 2 mmHg. Five intravenous boluses of mannitol 20% (0.4 g/kg) or HS 7.2% (1 mL/kg) were administered, each 15 min apart. A 2-day washout period ensued, and the procedure was repeated with the other hyperosmotic age...
Pozor MA, Macpherson ML, Kelleman AA, Smith H, McNaughten JW.This retrospective study aimed to validate the usefulness of spectral Doppler ultrasonography in diagnosing testicular dysfunction in stallions. The first part of the study included a pony stallion with age-related testicular degeneration (18 - 21 yrs. old). Testicular dimensions, spectral Doppler parameters of testicular blood flow, and semen parameters were obtained numerous times from this pony over four consecutive years. While testicular volume decreased dramatically, and the stallion became azoospermic, there were no changes in any of the spectral Doppler parameters of testicular blood f...
Harbowy RM, Nielsen BD, Colbath AC, Robison CI, Buskirk DD, Logan AA.Though circular exercise is commonly used in equestrian disciplines, it may be at the detriment of horses' musculoskeletal system. To investigate the effects of circular exercise on bone and joint health, 42 lambs were randomly assigned to a non-exercised control, straight-line, small circle, or large circle exercise regime at a slow (1.3 m/s) or fast (2.0 m/s) speed for 12 wk. Blood samples were taken biweekly. Animals were humanely euthanized upon study completion, and the fused third and fourth metacarpals were collected for biomechanical testing and bone density analysis. Fast groups were ...
King MR, Colla S.Successful rehabilitation of muscle injury requires a comprehensive understanding of the injury process, healing phases, and resources to be employed. The initial phase is characterized by acute inflammatory signs, followed by the regenerative and remodeling phases. Therapeutic exercises can be utilized in all 3 phases, progressing from isometric exercises to aquatic therapies. The classification and phase of injury and the individual response to the applied therapies will guide the progression of the therapeutic exercises through the rehabilitation program.
Lindqvist A, Nyman G, Rydén A, Wattle O.This study aimed to assess and compare the recovery of ponies and horses following general anesthesia in two different settings: a recovery box with an inflexible, adjustable ceiling, and free recovery without restraints. Our primary objective was to evaluate the effect of adjustable ceilings on the prevention of premature attempts to rise during recovery. The secondary aim was to compare the physiological stress indicators during recovery. Methods: Prospective, randomized, experimental study. Methods: Six healthy ponies and 10 healthy horses. Methods: This study used a crossover design with t...
McKenzie E.The equine muscle system is complex and prone to a large range of hereditary and acquired diseases that often have overlapping clinical signs with orthopedic, neurologic, and other disorders. Obtaining a clinical history that fully outlines the client concerns and any known information about the disorder and following with a comprehensive physical examination and screening clinical pathology tests are fundamental to achieve definitive diagnosis. A methodical and comprehensive approach aids accurate diagnosis and development of an optimal treatment and management plan. This article describes th...
Drzewiecka EM, Molcan T, Sadowska A, Piotrowska-Tomala K, Słyszewska M, Dias GF, Skarżyński DJ, Szóstek-Mioduchowska A.Mares with endometrosis exhibit histological changes not only in the endometrium but also in the myometrium that suggest possible functional impairment. The molecular background of these changes is not well understood. We hypothesize that the transcriptomic profile of the mare myometrium varies depending on the degree of endometrosis in mares. Myometria were collected from mares in the mid-luteal phase of the estrous cycle with endometrium categories I, IIA, IIB, and III (∑n = 23), according to Kenney and Doig´s histopathological classification. Myometrial RNA was isolated and subjected...
Rossi HS, Mykkänen AK, Junnila JJT, Hyytiäinen HK.Pulse oximetry has not been thoroughly evaluated for assessment of oxygenation in conscious foals. Compared with invasive arterial blood sampling, it is a painless and non-invasive method for real-time monitoring of blood oxygen saturation. The aim of this prospective clinical study was to evaluate the usability, validity, and reliability of pulse oximetry at two measuring sites (lip and caudal abdominal skin fold) for blood oxygen saturation measurement in conscious foals with and without respiratory compromise. Thirty-two foals under one month of age were used. Nineteen foals had normal resp...
Dufourni A, Demeyere M, Vera L, van Loon G, Decloedt A.This study aimed to compare two-dimensional, M-mode, color, pulsed-wave Doppler (PWD) and continuous-wave Doppler (CWD) echocardiography, and PWD ultrasonography of the caudal common carotid artery (CCA) in horses with aortic regurgitation (AR). Methods: Warmblood horses without (n = 20) and with mild, moderate, and severe AR (n = 60) were included in the study. Methods: A retrospective descriptive study focused on cardiac dimensions, aortic and CCA Doppler flow. Non-invasive blood pressure and presence of ventricular arrhythmia were recorded. Groups were compared using analysis of varianc...
Spicer LJ, Maylem ERS, Schütz LF.Ovarian granulosa cells produce a variety of biologically active compounds in addition to steroid hormones that include numerous families of growth factors, cytokines and adipokines. Many of these function as endocrine, paracrine and autocrine hormones to regulate ovarian activity. The goal of this review is to provide an update on the evidence in domestic animals on how FSH, insulin and IGF1 regulate the function of granulosa cells with a focus on ovarian steroidogenesis and cell proliferation with comparisons across six domestic animals: pigs, cattle, horses, water buffalo, goats and sheep. ...
The response to exercise following a rest period may vary among horse breeds based on the importance of the hematological and hematochemical profiles of athletic horses. Ten Standardbred and ten Italian Saddlebred mares were subjected to a 4-week training program after a seasonal rest, and hematological parameters (red blood cells-RBCs; hemoglobin-Hb; hematocrit-Hct; platelets-PLTs; platelet aggregation-AG; aggregation slope-Slope; fibrinogen-Fb), as well as Albumin (Alb) and non-esterified fatty acids (NEFAs), were analyzed. Blood samples were obtained each week during the training program fo...
Haussler KK, le Jeune SS, MacKechnie-Guire R, Latif SN, Clayton HM.The defining characteristic of laterality is the dominance of one side of the brain controlling specific functions of paired organs or on one side of the body. Structural and functional asymmetries are ubiquitous in horses and range from anatomical features (e.g., the length of long bones) to the gathering of sensory information (e.g., which eye is used to observe unfamiliar scenes) and motor functions (e.g., left-right differences in locomotion). There is a common tendency to assign observed structural or functional asymmetries to lateralization, which often involves more than a simple left-r...
Toupadakis CA, Wong A, Genetos DC, Cheung WK, Borjesson DL, Ferraro GL, Galuppo LD, Leach JK, Owens SD, Yellowley CE.To determine the optimal osteogenic source of equine mesenchymal stem cells (eMSCs) and optimize collection of and expansion conditions for those cells. Methods: 10 adult Quarter Horses and 8 newborn Thoroughbred foals. Methods: eMSCs were isolated from bone marrow (BM), adipose tissue, and umbilical cord blood and tissue, and the osteogenic potential of each type was assessed. Effects of anatomic site, aspiration volume, and serum type on eMSC yield from BM were investigated. Results: BM-eMSCs had the highest overall expression of the osteogenic genes Cbfa1, Osx, and Omd and staining for ALP ...
Guo HY, Pang K, Zhang XY, Zhao L, Chen SW, Dong ML, Ren FZ.This study investigated the changes in chemical composition, nitrogen fraction distribution, and AA profile of milk samples obtained during lactation from the Jiangyue breed of donkey in Northwest China. Results showed that donkey milk contained 9.53% total solids, 1.57% protein, 1.16% fat, 6.33% lactose, and 0.4% ash on average, which is more similar to mare and human milk than to the milk of other mammals. Throughout the lactation investigated, pH and density were constant, protein and ash content showed an apparent negative trend (an increase in lactose content during 120 d postpartum, foll...
Dudhia J, Scott CM, Draper ER, Heinegård D, Pitsillides AA, Smith RK.Age-associated and degenerative loss of functional integrity in soft tissues develops from effects of cumulative and subtle changes in their extracellular matrix (ECM). The highly ordered tendon ECM provides the tissue with its tensile strength during loading. As age and exercise collide in the high incidence of tendinopathies, we hypothesized that aged tendons fail due to cumulative damage resulting from a combination of diminished matrix repair and fragmentation of ECM proteins induced by prolonged cyclical loading, and that this is an active cell-mediated process. We developed an equine ten...
Hirst SJ, Martin JG, Bonacci JV, Chan V, Fixman ED, Hamid QA, Herszberg B, Lavoie JP, McVicker CG, Moir LM, Nguyen TT, Peng Q, Ramos-Barbón D....Increased airway smooth muscle (ASM) mass is perhaps the most important component of the airway wall remodeling process in asthma. Known mediators of ASM proliferation in cell culture models fall into 2 categories: those that activate receptors with intrinsic receptor tyrosine kinase activity and those that have their effects through receptors linked to heterotrimeric guanosine triphosphate-binding proteins. The major candidate signaling pathways activated by ASM mitogens are those dependent on extracellular signal-regulated kinase and phosphoinositide 3'-kinase. Increases in ASM mass may also...
Soave O, Brand CD.Coprophagy is performed by rodents and lagomorphs and to a lesser degree by piglets, foals, dogs and nonhuman primates. Due to the construction of the digestive system of rodents and rabbits, coprophagy is necessary to supply many essential nutrients. Bacterial synthesis of nutrients occurs in the lower gastrointestinal tract in these animals where little absorption is realized. The eating of their feces provides a method for obtaining these nutrients.
Thorpe CT, Godinho MSC, Riley GP, Birch HL, Clegg PD, Screen HRC.While the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the cost of locomotion. Energy storing tendons experience extremely high strains and need to be able to recoil efficiently for maximum energy storage and return. In the equine forelimb, the energy storing superficial digital flexor tendon (SDFT) has much higher failure strains than the positional common digital extensor tendon (CDET). However, we have previously shown that this is not due to differences in the properties of...
Witte TH, Knill K, Wilson AM.Measurement of peak vertical ground reaction force (GRFz) from multiple limbs simultaneously during high-speed, over-ground locomotion would enhance our understanding of the locomotor mechanics of cursorial animals. Here, we evaluate the accuracy of predicting peak GRFz from duty factor (the proportion of the stride for which the limb is in contact with the ground). Foot-mounted uniaxial accelerometers, combined with UHF FM telemetry, are shown to be practical and accurate for the field measurement of stride timing variables, including duty factor. Direct comparison with the force plate produc...
Costa MC, Weese JS.The equine intestinal tract contains a complex microbial population (microbiota) that plays an important role in health and disease. Despite the undeniable importance of a 'normal' microbiota, understanding of the composition and function of this population is currently limited. As methods to characterize the microbiota and its genetic makeup (the microbiome) have evolved, the composition and complexity of this population are starting to be revealed. As is befitting a hindgut fermenter, members of the Firmicutes phylum appear to predominate, yet there are significant populations of numerous ot...
Proops L, McComb K.It has recently been shown that some non-human animals can cross-modally recognize members of their own taxon. What is unclear is just how plastic this recognition system can be. In this study, we investigate whether an animal, the domestic horse, is capable of spontaneous cross-modal recognition of individuals from a morphologically very different species. We also provide the first insights into how cross-modal identity information is processed by examining whether there are hemispheric biases in this important social skill. In our preferential looking paradigm, subjects were presented with t...
Prokhorov NS, Riccio C, Zdorovenko EL, Shneider MM, Browning C, Knirel YA, Leiman PG, Letarov AV.Bacteriophages recognize and bind to their hosts with the help of receptor-binding proteins (RBPs) that emanate from the phage particle in the form of fibers or tailspikes. RBPs show a great variability in their shapes, sizes, and location on the particle. Some RBPs are known to depolymerize surface polysaccharides of the host while others show no enzymatic activity. Here we report that both RBPs of podovirus G7C - tailspikes gp63.1 and gp66 - are essential for infection of its natural host bacterium E. coli 4s that populates the equine intestinal tract. We characterize the structure and funct...
Cross AR, Higson FK, Jones OT, Harper AM, Segal AW.1. The absorption coefficient of human neutrophil plasma-membrane reduced-minus-oxidized cytochrome b-245 was determined [delta epsilon (mM; 559-540 nm) = 21.6 cm-1]. 2. Neutrophil polymorphonuclear leucocytes (neutrophils) were prepared from human, ox, horse and pig blood. In each case plasma-membrane fractions were found to contain low-potential cytochrome b. When membranes from horse neutrophils were incubated anaerobically with either NADH or NADPH the cytochrome b became reduced. Prior stimulation of the cells with phorbol myristate acetate did not increase the rate or extent of cytochrom...
Whittle BJ, Moncada S, Vane JR.The activity of prostacyclin (PGI2), PGE1 or PGD2 as inhibitors of platelet aggregation in plasma from human, dog, rabbit, rat, sheep and horse was investigated. Prostacyclin was the most potent inhibitor in all species. PGD2 was a weak inhibitor in dog, rabbit and rat plasma whereas PGE1 and prostacyclin were highly active. Theophylline or dipyridamole potentiated the inhibition of human platelet aggregation by prostacyclin, PGE1 or PGD2. Compound N-0164 abolished the inhibition by PGD2 of human platelet aggregation but did not inhibit the effects of PGE1 or prostacyclin. The results suggest ...
Johnson L, Thompson DL, Varner DD.Testicular function is under the control of expression and repression of several genes and gene products, and many of these works through Sertoli cells. The capability of Sertoli cells to regulate spermatogenesis is dependent on Sertoli cell functions and Sertoli cell number. Sertoli cell number has long been thought to be stable in adults with no proliferation of Sertoli cells once adult numbers have been reached. However, adult horses do not have stable Sertoli cell numbers, and new studies indicate that adult Sertoli cells can be made to re-enter mitotic phase under certain experimental con...
Gibb Z, Lambourne SR, Aitken RJ.The relationship between stallion fertility and oxidative stress remains poorly understood. The purpose of this study was to identify criteria for thoroughbred fertility assessment by performing a logistical regression analysis using "dismount" sperm parameters as predictors and weekly per-cycle conception rate as the dependent variable. Paradoxically, positive relationships between fertility and oxidative stress were revealed, such that samples that produced pregnancies exhibited higher rates of 8-hydroxy-2'-deoxyguanosine release (1490.2% vs. 705.5 pg/ml/24 h) and lower vitality (60.5% vs. 6...
Minetti AE, ArdigO LP, Reinach E, Saibene F.Three-dimensional motion capture and metabolic assessment were performed on four standardbred horses while walking, trotting and galloping on a motorized treadmill at different speeds. The mechanical work was partitioned into the internal work (W(INT)), due to the speed changes of body segments with respect to the body centre of mass, and the external work (W(EXT)), due to the position and speed changes of the body centre of mass with respect to the environment. The estimated total mechanical work (W(TOT)=W(INT)+W(EXT)) increased with speed, while metabolic work (C) remained rather constant. A...
Wilson AM, McGuigan MP, Su A, van Den Bogert AJ.The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes...
Möstl E, Messmann S, Bagu E, Robia C, Palme R.After 14C-labelled cortisol infusion in ponies and pigs, faecal samples were collected. Extraction of 0.5 g faeces with 5 ml 80-90% methanol yielded the highest radioactivity in the supernatant. Most of the metabolites were ether soluble. After high performance liquid chromatography (HPLC), the presence of immunoreactive metabolites was demonstrated by measuring each HPLC fraction using enzyme immunoassays for cortisol, corticosterone and 11-oxoaetiocholanolone. Only the assay for 11-oxoaetiocholanolone revealed peaks with co-eluting radioactivity. For biological validation of the test system,...
Vick MM, Adams AA, Murphy BA, Sessions DR, Horohov DW, Cook RF, Shelton BJ, Fitzgerald BP.Recent studies associate obesity and insulin resistance in horses with development of abnormal reproductive function and debilitating laminitis. The factors contributing to insulin resistance in obese horses are unknown. However, human studies provide evidence that elevated inflammatory cytokines such as tumor necrosis factor alpha (TNFalpha), IL1, and IL6 play direct roles in development of obesity-associated insulin resistance. Thus, inflammation may be a key link between obesity and insulin resistance in horses. The aim of the current investigation was to examine possible relationships betw...
Carter CA, Jolly DG, Worden CE, Hendren DG, Kane CJ.Nonhealing wounds of the lower equine limb represent a challenging model. The platelet is a natural source of a myriad of growth factors and cytokines that promote wound healing. This study evaluates the potential of platelet derived factors to enhance wound healing in the lower equine limb. Platelets were isolated from horse blood and activated with thrombin, a process known to induce growth factor release. This produced a platelet gel composed of platelet-rich plasma (PRP). To test this all-natural wound healant, 2.5-cm(2) full thickness cutaneous wounds were created below the knee and hock ...
Costa MC, Weese JS.This article provides readers with the basic concepts necessary to understand studies using recent molecular methods performed in intestinal microbiome assessment, with special emphasis on the high throughput sequencing. This review also summarizes the current knowledge on this topic and discusses future insights on the interaction between the intestinal microbiome and equine health.
Patterson-Kane JC, Becker DL, Rich T.The equine superficial digital flexor tendon (SDFT) is a frequently injured structure that is functionally and clinically equivalent to the human Achilles tendon (AT). Both act as critical energy-storage systems during high-speed locomotion and can accumulate exercise- and age-related microdamage that predisposes to rupture during normal activity. Significant advances in understanding of the biology and pathology of exercise-induced tendon injury have occurred through comparative studies of equine digital tendons with varying functions and injury susceptibilities. Due to the limitations of in-...
Ayliffe LK, Cerling TE, Robinson T, West AG, Sponheimer M, Passey BH, Hammer J, Roeder B, Dearing MD, Ehleringer JR.Temporal stable isotope records derived from animal tissues are increasingly studied to determine dietary and climatic histories. Despite this, the turnover times governing rates of isotope equilibration in specific tissues following a dietary isotope change are poorly known. The dietary isotope changes recorded in the hair and blood bicarbonate of two adult horses in this study are found to be successfully described by a model having three exponential isotope pools. For horse tail hair, the carbon isotope response observed following a dietary change from a C3 to a C4 grass was consistent with...
Adams MR, Register TC, Golden DL, Wagner JD, Williams JK.Although estrogen replacement therapy is associated with reduced risk of coronary heart disease and reduced extent of coronary artery atherosclerosis, the effects of combined (estrogen plus progestin) hormone-replacement therapy are uncertain. Some observational data indicate that users of combined hormone replacement consisting of continuously administered oral conjugated equine estrogens (CEE) and oral sequentially administered (7 to 14 days per month) medroxyprogesterone acetate (MPA) experience a reduction in risk similar to that of users of CEE alone. However, the effects of combined, con...
Dowling BA, Dart AJ, Hodgson DR, Smith RK.The superficial digital flexor tendon (SDFT) is an elastic structure that during maximal exercise appears to operate close to its functional limits. The biomechanical and biochemical responses to exercise, injury, and healing are still poorly understood but ongoing research is providing valuable new information which is addressed in this review. It appears that the SDFT matures early, after which time it has limited ability to adapt to stress and undergoes progressive degeneration. Focal hypocellularity, collagen fibril degeneration, selective fibril loading and alterations in the noncollageno...
Schmidt A, Möstl E, Wehnert C, Aurich J, Müller J, Aurich C.Based on plasma cortisol concentrations it is widely accepted that transport is stressful to horses. So far, cortisol release during transport has not been evaluated in depth by non-invasive techniques such as analysis of salivary cortisol and faecal cortisol metabolites. Transport also causes changes in heart rate and heart rate variability (HRV). In this study, salivary cortisol, faecal cortisol metabolites, heart rate and HRV in horses transported by road for short (one and 3.5 h) and medium duration (8 h) were determined. With the onset of transport, salivary cortisol increased immediately...
Carrade Holt DD, Wood JA, Granick JL, Walker NJ, Clark KC, Borjesson DL.Mesenchymal stem cells (MSCs) are used in both human clinical trials and veterinary medicine for the treatment of inflammatory and immune-mediated diseases. MSCs modulate inflammation by decreasing the cells and products of the inflammatory response. Stimulated equine MSCs from bone marrow (BM), adipose tissue (AT), cord blood (CB), and umbilical cord tissue (CT) inhibit lymphocyte proliferation and decrease inflammatory cytokine production. We hypothesized that equine MSCs inhibit T cell proliferation through secreted mediators and that MSCs from different tissue sources decrease T cell proli...
Kriek NP, Kellerman TS, Marasas WF.An isolate of Fusarium verticillioides (MRC826) that induced experimental leukoencephalomalacia, also caused acute toxicity when fed to pigs and administered per rumen fistula to sheep. Pigs developed severe pulmonary oedema while sheep manifested severe nephrosis and hepatosis. A less toxic isolate (F. verticillioides MRC602), fed to baboons, resulted in acute congestive heart failure or hepatic cirrhosis, depending on the dose. Both isolates were toxic to rats and caused similar lesions, namely, hepatic cirrhosis and intraventricular cardiac thrombosis.
