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.
Bertuglia A, Lacourt M, Girard C, Beauchamp G, Richard H, Laverty S.The role of osteoclasts in osteochondral degeneration in osteoarthritis (OA) has rarely been investigated in spontaneous disease or animal models of OA. Objective: The objectives of the current study were to investigate osteoclast density and location in post-traumatic OA (PTOA) and control specimens from racehorses. Methods: Cores were harvested from a site in the equine third carpal bone, that undergoes repetitive, high intensity loading. Histological and immunohistochemical (Cathepsin K and Receptor-activator of Nuclear Factor kappa-β ligand (RANKL)) stained sections were scored (global an...
Medina-Torres CE, Underwood C, Pollitt CC, Castro-Olivera EM, Hodson MP, Richardson DW, van Eps AW.A suitable method for evaluating lamellar perfusion changes and their metabolic consequences is currently lacking. Objective: To examine perfusion changes in lamellar tissue using serial microdialysis measurements of urea clearance and energy metabolites. Methods: Randomised, controlled (within subject) experimental trial. Methods: Nine Standardbred horses were instrumented with microdialysis probes in the foot lamellar tissue and skin (over the tail base). Urea (20 mmol/l) was added to the perfusate and its clearance was used to estimate local perfusion. Samples were collected every 15 min fo...
Darwish WS, Ikenaka Y, Morshdy AE, Eldesoky KI, Nakayama S, Mizukawa H, Ishizuka M.The aim of this study was to estimate total carotenoids, β-carotene and retinol concentrations in the livers and muscles of some ungulates (cattle, buffalo, sheep, goats and horses) in comparison with the Wistar rats as a control. Cattle and horses had the highest contents of total carotenoids and β-carotene. Unexpectedly, sheep was the highest accumulator of retinol with a mean concentration of 203 ± 23.34 µg/g, while the least accumulator was buffalo, having a mean value of 58.28 ± 13.77 µg/g. Livers had higher contents of the examined phytochemicals than muscles. Consumption of these ...
Yamazaki M, Kusano K, Ishibashi T, Kiuchi M, Koyama K.Upon intensive, exhaustive exercise, exercise-induced reactive oxygen species may exceed the antioxidant defence threshold, consequently resulting in muscular damage or late-onset chronic inflammation. Recently, the therapeutic antioxidant and anti-inflammatory effects of molecular hydrogen (H2) for human rheumatoid arthritis have been demonstrated. However, it is also important to clarify the effects of administrating H2 in large animals other than humans, as H2 is thought to reach the target organ by passive diffusion upon delivery from the blood flow, indicating that the distance from the a...
Mastellar SL, Barnes T, Cybulak K, Urschel KL.This study determined splanchnic extraction of phenylalanine at two intakes of threonine. Six Thoroughbred mares were supplemented with isonitrogenous amounts of either threonine or glutamate. Dietary threonine intakes were 119 (+Thr) and 58 (Basal) mg/kg/day, respectively. Each horse received each diet twice and each was studied once with an oral and once with an intravenous (IV) infusion of [1-(13)C]phenylalanine. A 2-h primed, constant IV infusion of [(13)C]sodium bicarbonate and a 4-h primed, constant infusion of [1-(13)C]phenylalanine, either orally or IV, were used to measure isotopic en...
Muñoz A, Esgueva M, Gómez-Díez M, Serrano-Caballero JM, Castejón-Riber C, Serrano-Rodríguez JM.Changes in blood pressure (BP) during acute hypertension in response to angiotensin-converting enzyme inhibitors (ACEIs) have not been investigated in normotensive horses. In this study, six healthy horses were subjected to five trials, consisting in a treadmill exercise workload of 8 m/s for 1 min, 2 h after oral administration (PO) of placebo (0 mg/kg), enalapril (2.0 mg/kg), quinapril (1.0 mg/kg), ramipril (0.2 mg/kg) or benazepril (0.5 mg/kg). Serum angiotensin converting enzyme (ACE) activity was measured and systolic (SBP) and diastolic (DBP) blood pressures were recorded...
Orlando L.Alongside domestic horses and donkeys, the horse family, also known as equids, comprises six extant wild species of asses and zebras (Figure 1). Equids are extremely well represented in the fossil record, comprising a 55 million-year evolutionary history, punctuated by many episodes of innovation, extinction and migration. Limited to the single genus Equus today, in the Miocene (23.0–5.3 million years ago) the equid family flourished, comprising more than twenty genera. The group originated in Northern America, where the earliest fossil forms have been found, the so-called Hyracotheres, no l...
Olsen E, Pedersen TL, Robinson R, Haubro Andersen P.Arterial blood pressure (BP) is a relevant clinical parameter that can be measured in standing conscious horses to assess tissue perfusion or pain. However, there are no validated oscillometric noninvasive blood pressure (NIBP) devices for use in horses. Methods: Seven healthy horses from a teaching and research herd. Objective: To evaluate the accuracy and precision of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) in conscious horses obtained with an oscillometric NIBP device when compared to invasively measured arterial BP. Methods: An ...
Hepworth-Warren KL, Wong DM, Hay-Kraus BL, Wang C, Sun Y.This study compared the effects of IV administration of isotonic fluid therapy and colloidal fluid therapy in healthy neonatal foals. Fifteen healthy neonatal foals were used in a randomized blinded prospective clinical study. Foals were randomly assigned to receive a bolus of 20 mL/kg of tetrastarch (TES) or balanced crystalloid solution. Vital parameters, colloid osmotic pressure (COP), and various clinicopathologic variables were assessed prior to infusion and at various time points up to 120 h after infusion. The treatment group (TES) had a significant increase in both COP and percentage i...
Jensen RB, Kyrstein TD, Junghans P, Tauson AH.Energy expenditure (EE) can be estimated based on respiratory gas exchange measurements, traditionally done in respiration chambers by indirect calorimetry (IC). However, the (13)C-bicarbonate technique ((13)C-BT) might be an alternative minimal invasive method for estimation of CO(2) production and EE in the field. In this study, four Shetland ponies were used to explore the effect of feeding on CO(2) production and EE measured simultaneously by IC and (13)C-BT. The ponies were individually housed in respiration chambers and received either a single oral or intravenous (IV) bolus dose of (13)...
González-Fernández L, Macedo S, Lopes JS, Rocha A, Macías-García B.Equine in vitro fertilization (IVF) is still inconsistent. In the present work, we studied how modified Whitten's (MW) medium and Tissue Culture Medium 199 (TCM) added with Foetal Bovine Serum (FBS; 10% v/v) or Bovine Serum Albumin (BSA; 7 mg/ml) affected equine gametes to subsequently run IVF trials. Compact (Cp) and expanded (Ex) cumuli equine oocytes were matured and placed in TCM or MW supplemented with BSA or FBS for 18-20 h (no sperm added). In Ex oocytes, TCM-199 added with FBS or BSA resulted in higher metaphase II (MII) rates (75.7% and 62.7%, respectively) than MW added with BSA (54%...
Lanata A, Guidi A, Baragli P, Valenza G, Scilingo EP.This study reports on a novel method to detect and reduce the contribution of movement artifact (MA) in electrocardiogram (ECG) recordings gathered from horses in free movement conditions. We propose a model that integrates cardiovascular and movement information to estimate the MA contribution. Specifically, ECG and physical activity are continuously acquired from seven horses through a wearable system. Such a system employs completely integrated textile electrodes to monitor ECG and is also equipped with a triaxial accelerometer for movement monitoring. In the literature, the most used techn...
Plaza Dávila M, Bucci D, Galeati G, Peña FJ, Mari G, Giaretta E, Tamanini C, Spinaci M.Stallion spermatozoa are highly dependent on oxidative phosphorylation for ATP production to achieve normal sperm function and to fuel the motility. The aim of this study was to evaluate the response of equine sperm under capacitating conditions to the inhibition of mitochondrial complex I by rotenone and to test whether epigallocatechin-3-gallate (EGCG), a natural polyphenol component of green tea, could counteract this effect. After 2-h incubation of stallion spermatozoa in modified Tyrode's medium, rotenone (100 nm, 500 nm and 5 μm) and EGCG (10, 20 and 60 μm), alone or in combination, di...
Kim JY, Jung HJ, Yoon MJ.Expression of the protein DDX4/MVH, or VASA, has been reported in germ cells of several species. The main objectives of this study were to (i) investigate VASA expression patterns in testicular cells of stallions at two different reproductive stages (pre-pubertal and post-pubertal) and (ii) evaluate the use of VASA antibody as a molecular marker for single germ cells from stallions. Testicular tissues were obtained from stallions and categorized as pre-pubertal and post-pubertal based on the formation of lumen and status of spermatogenesis on the cross section of seminiferous tubules. The resu...
Castro T, Oliveira FA, Siddiqui MA, Baldrighi JM, Wolf CA, Ginther OJ.A study was performed on the effect of a single dose per mare of 0 (n = 9), 100 (n = 8), or 300 (n = 9) of GnRH on Day 10 (Day 0 = ovulation) on concentrations of LH, FSH, and progesterone (P4) and blood flow to the CL ovary. Hormone concentration and blood flow measurements were performed at hours 0 (hour of treatment), 0.25, 0.5, 1, 2, 3, 4, and 6. Blood flow was assessed by spectral Doppler ultrasonography for resistance to blood flow in an ovarian artery before entry into the CL ovary. The percentage of the CL with color Doppler signals of blood flow was estimated from videotapes of real-t...
Cheetham J, Perkins JD, Jarvis JC, Cercone M, Maw M, Hermanson JW, Mitchell LM, Piercy RJ, Ducharme NG.Bilateral vocal fold paralysis (BVCP) is a life-threatening condition that follows injury to the Recurrent Laryngeal nerve (RLn) and denervation of the intrinsic laryngeal musculature. Functional electrical stimulation (FES) enables restoration and control of a wide variety of motor functions impaired by lower motor neuron lesions. Here we evaluate the effects of FES on the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle in a large animal model of RLn injury. Ten horses were instrumented with two quadripolar intramuscular electrodes in the left PCA muscle. Following a 12-wee...
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...
Bonelli F, Meucci V, Divers TJ, Jose-Cunilleras E, Corazza M, Tognetti R, Guidi G, Intorre L, Sgorbini M.The diseases most frequent associated with SIRS in adult horses are those involving the gastrointestinal tract. An early diagnosis should be the goal in the management of horses with SIRS. Objective: The objective of this study was to evaluate the plasma procalcitonin (PCT) concentration in healthy and SIRS horses to assess differences between the two groups. Methods: Seventy-eight horses (30 healthy and 48 SIRS). Methods: Prospective in vivo multicentric study. Horses were classified as SIRS if at least 2 of the following criteria were met: abnormal leukocyte count or distribution, hypertherm...
Turło A, Cywińska A, Czopowicz M, Witkowski L, Niedźwiedź A, Słowikowska M, Borowicz H, Jaśkiewicz A, Winnicka A.Training-induced muscle, skeletal and joint trauma may result in acute phase response reflected by the changes in the blood concentration of serum amyloid A (SAA) in racehorses. It remains yet unclear if such systemic reaction could be triggered by sport injuries and what is the impact of different types of musculoskeletal trauma on SAA concentrations in racehorses. This study aimed to determine changes in the SAA blood concentration in racehorses with different types of injuries of musculoskeletal system. Methods: The study involved 28 racehorses diagnosed after the race with bone fractures (...
Klein C.Few, if any, biological processes are as diverse among domestic species as establishment of early pregnancy, in particular maternal recognition of pregnancy. Following fertilization and initial development in the mare oviduct, selective transport of the embryo through the uterotubal junction driven by embryo-derived PGE2 occurs. Upon arrival in the uterus, an acellular glycoprotein capsule is formed that covers the embryo, blastocyst, and conceptus (embryo and associated extraembryonic membranes) between the second and third weeks of pregnancy. Between Days 9 and 15/16 of pregnancy, the concep...
Mastellar SL, Moffet A, Harris PA, Urschel KL.Current equine threonine requirement estimates do not account for probable use of threonine to maintain gut health and mucin synthesis. The objective of this study was to determine if threonine supplementation (+Thr) would increase whole-body protein synthesis (WBPS) in weanling colts (Study 1) and adult mares (Study 2). Both studies used a crossover design, where each of six animals was studied twice while receiving the isonitrogenous diets. The basal diets contained lower threonine levels (Basal) than the threonine (+Thr) supplemented diets. Threonine intakes in mg/kg BW/day were as follows:...
Stefaniuk M, Ropka-Molik K.RNA sequencing (RNA-seq) by next-generation technology is a powerful tool which creates new possibilities in whole-transcriptome analysis. In recent years, with the use of the RNA-seq method, several studies expanded transcriptional gene profiles to understand interactions between genotype and phenotype, supremely contributing to the field of equine biology. To date, in horses, massive parallel sequencing of cDNA has been successfully used to identify and quantify mRNA levels in several normal tissues, as well as to annotate genes. Moreover, the RNA-seq method has been applied to identify the ...
Stefánsdóttir GJ, Ragnarsson S, Gunnarsson V, Roepstorff L, Jansson A.This study compared the effect of ridden tölt and trot at 3 speeds on physiological responses in trained adult (15.3 ± 1.6 yr) Icelandic horses. The experiment had a crossover design with 8 horses, 2 treatments (incremental exercise test in tölt and trot), and 2 riders. Each horse performed 2 tests per day (1 gait with 2 riders, minimum 4.5 h between) on 2 separate days, with 1 d of rest in between. The exercise test consisted of three 642-m phases at 3.0 m/s (Speed), 4.0 m/s (Speed), and 5.0 m/s (Speed) and was performed outdoors on a 300-m oval gravel riding track in northern Iceland in M...
Jellyman JK, Valenzuela OA, Fowden AL.Adrenal glucocorticoids, such as cortisol, are essential for normal fetal development and for maintaining homeostasis in adults. Developmental studies in humans and other animals have shown that exposure to excess glucocorticoids during critical windows of perinatal development can program permanent changes in hypothalamic-pituitary-adrenal (HPA) axis function and metabolic function, with adverse implications for the long-term health of the exposed offspring. The current review compares the programming of postnatal HPA axis function and glucose homeostasis among different species overexposed p...
Bamford NJ, Baskerville CL, Harris PA, Bailey SR.The enteroinsular axis is a complex system that includes the release of incretin hormones from the gut to promote the absorption and utilization of glucose after a meal. The insulinogenic effect of incretin hormones such as glucagon-like peptide-1 (GLP-1) remains poorly characterized in the horse. The aim of this study was to compare postprandial glucose, insulin, and GLP-1 responses of different equine breeds adapted to twice-daily meals containing micronized maize. Four Standardbred horses, 4 mixed-breed ponies, and 4 Andalusian cross horses in moderate BCS (5.5 ± 0.2 out of 9) were fed mea...
Van de Water E, Oosterlinck M, Pille F.The effects of handler position and perineural anaesthesia in sound horses need investigation to facilitate interpretation of pressure plate analysis in lame horses. Objective: To evaluate the effect of handler position and perineural anaesthesia on limb loading and particularly hoof balance in sound horses. Methods: Nonrandomised crossover study. Methods: Six sound horses were walked and trotted over a pressure plate, with the handler on the left and subsequently on the right side, and finally after a bilateral low palmar digital nerve block. One week later this procedure was repeated before ...
Corado CR, McKemie DS, Young A, Knych HK.Metabolism is an essential factor in the clearance of many drugs and as such plays a major role in the establishment of dosage regimens and withdrawal times. CYP2D6, the human orthologue to equine CYP2D50, is a drug-metabolizing enzyme that is highly polymorphic in humans leading to widely differing levels of metabolic activity. As CYP2D6 is highly polymorphic, in this study it was hypothesized that the gene coding for the equine orthologue, CYP2D50, may also be prone to polymorphism. Blood samples were collected from 150 horses, the CYP2D50 gene was cloned and sequenced; and full-length seque...
Wu Z, Zheng X, Luo Y, Huo F, Dong H, Zhang G, Yu W, Tian F, He L, Chen J.The present study investigates the effects of five cryoprotectants (CPAs) and cryoprotectant combinations on the post-thaw total motility, progressive motility, viability, mitochondrial membrane potential and acrosome integrity in stallion spermatozoa. In Experiment 1, the objective was to compare the impact of different concentrations (2.5%, 3.5% and 5%) of a single CPA, including glycerol (Gly), ethylene glycol (EG), dimethyl sulphoxide (DMSO), methyl formamide (MF), and dimethylformamide (DMF) for stallion spermatozoa cryopreservation. In Experiment 2, two or more CPAs were used to assess w...
Ghassab S, Dulin J, Bertone AL.To compare clotting efficiency of platelet-rich plasma (PRP) and concentrated platelet-poor plasma (cPPP) to citrated whole blood after activation by autologous thrombin, bovine thrombin, or calcium chloride (CaCl2 ). Methods: Experimental study. Methods: Healthy adult horses (n = 6). Methods: PRP and cPPP were prepared by commercial devices. Using thromboelastography, clotting variables were compared after activation of citrated autologous blood, PRP, and cPPP by autologous thrombin, bovine thrombin, or CaCl2 , respectively. Results: PRP had the greatest clot strength and quickest clot rate, ...
Banse HE, Frank N, Kwong GP, McFarlane D.In horses, hyperinsulinemia and insulin resistance (insulin dysregulation) are associated with the development of laminitis. Although obesity is associated with insulin dysregulation, the mechanism of obesity-associated insulin dysregulation remains to be established. We hypothesized that oxidative stress in skeletal muscle is associated with obesity-associated hyperinsulinemia in horses. Thirty-five light breed horses with body condition scores (BCS) of 3/9 to 9/9 were studied, including 7 obese, normoinsulinemic (BCS ≥ 7, resting serum insulin < 30 μIU/mL) and 6 obese, hyperinsulinemic...
Bondo T, Jensen SK.This study assessed the effect of a vitamin E supplement given to pregnant mares on immunoglobulins (Ig) levels in foals. In addition, the fatty acid (FA) content and composition of the mares' milk was assessed. Milk α-tocopherol concentrations were compared between pregnant Danish Warmblood mares (n = 17) given a daily oral supplement of 2500 international units (IU) RRR-α-tocopherol in the last 4 weeks of pregnancy and a group of unsupplemented mares (n = 17) receiving 170-320 IU vitamin E daily originating from the feed. Milk α-tocopherol was higher in supplemented mares (36.7, 12.4 and ...
Melchert M, Aurich C, Aurich J, Gautier C, Nagel C.Mares usually give birth when they perceive their environment as safe and therefore disturbance at foaling may inhibit labor. In this study, foaling mares were transferred to an unfamiliar environment at rupture of the allantochorion (stress, n = 6) or were left undisturbed (control, n = 5). The progress of foaling, heart rate, heart rate variability (HRV) and plasma catecholamine, oxytocin and cortisol concentration were determined. In stressed mares, time from rupture of the allantochorion to appearance of the fetal feet (5.3 ± 1.1 vs. 1.6 ± 0.4 min) and total length of f...
Loux SC, Scoggin KE, Bruemmer JE, Canisso IF, Troedsson MH, Squires EL, Ball BA.MicroRNAs (miRNAs) are small, non-coding RNAs which are produced throughout the body. Individual tissues tend to have a specific expression profile and excrete many of these miRNAs into circulation. These circulating miRNAs may be diagnostically valuable biomarkers for assessing the presence of disease while minimizing invasive testing. In women, numerous circulating miRNAs have been identified which change significantly during pregnancy-related complications (e.g. chorioamnionitis, eclampsia, recurrent pregnancy loss); however, no prior work has been done in this area in the horse. To identif...
Dittmann MT, Kreuzer M, Runge U, Clauss M.Horses achieve a higher degree of particle size reduction through ingestive mastication than functional ruminants. We characterized mastication using chew-monitoring halters (RumiWatch) in six domestic horses, cattle, and Bactrian camels each. All animals were offered grass hay of the same batch for 15 min. In cattle and camels, measurements were continued after eating until rumination was observed. Except for one horse, 96% of the horses' ingestive mastication data were identified as "rumination" by the proprietary RumiWatch algorithm, whereas ingestion and rumination by cattle and camels wer...
Kwan C, Bell R, Koenig T, Bischofberger A, Horadagoda N, Perkins NR, Jeffcott LB, Dart AJ.Evaluate synovial fluid cytology, total protein concentration and viscosity after intra-articular administration of combined pentosan polysulfate and glucosamine in horses. Methods: Ten adult Standardbred horses had each carpal joint (n = 20) randomly assigned to one of two treatments: control (5 mL saline) or treated (pentosan polysulfate and glucosamine). All horses received an intra-articular injection every 7 days for 3 weeks and synovial fluid samples were collected on days 1 (baseline), 2, 3, 7, 8, 9, 14, 15, 16 and 21. Synovial fluid variables measured included total protein concentrati...
Gibson C, de Ruijter-Villani M, Rietveld J, Stout TAE.Glucose is the primary energy substrate for early conceptus development and, for the first 40 days of gestation, the equine conceptus depends solely on glucose available in the histotroph; thereafter, histotrophic glucose provision continues to support transport across the definitive placenta. To investigate glucose provision routes during early equine pregnancy we examined expression of glucose transporters in conceptus membranes and endometrium recovered on days 7, 14, 21 and 28 after ovulation. To further differentiate the contributions of maternal progesterone priming and conceptus-endomet...
de Laat MA, Clement CK, Sillence MN, McGowan CM, Pollitt CC, Lacombe VA.An increased incidence of metabolic disease in horses has led to heightened recognition of the pathological consequences of insulin resistance. Laminitis, failure of the weightbearing digital lamellae, is an important consequence. Altered trafficking of specialised glucose transporters (GLUTs), responsible for glucose uptake, is central to the dysregulation of glucose metabolism and may play a role in the pathophysiology of laminitis. Objective: We hypothesised that prolonged hyperinsulinaemia alters the regulation of glucose transport in insulin-sensitive tissue and digital lamellae. Our obje...
Sykes BW, Underwood C, Greer R, McGowan CM, Mills PC.Conflicting data are presented in the current literature regarding the efficacy of omeprazole for suppressing gastric acidity in the horse. Objective: The objective of this study was to investigate the duration of intraday acid suppression achieved with two doses of omeprazole under two different dietary conditions. Methods: A four-way crossover design. Methods: Six adult Thoroughbred horses instrumented with percutaneous gastrotomy tubes were used. Intragastric pH was measured for continuous 23 h periods (08.00-07.00 h) for six consecutive days (Days 0-5). Baseline data was recorded on Day 0 ...
Müller K, Ellenberger C, Hoppen HO, Schoon HA.The first part of our study (Müller et al., 2009) characterized angiogenesis in the equine cycling ovary through histomorphological and immunohistochemical examinations (vascular endothelial growth factors A and B [VEGF A, VEGF B], vascular endothelial growth factor receptors 1 and 2 [VEGF-R1, VEGF-R2], vascular angiopoietins 1 and 2 [Ang1, Ang2], angiopoietin receptor [Tie2], and von Willebrand Factor). Since angiogenesis plays an important role in development and growth of numerous tumours, the second part of our study involved a similar examination of 70 equine granulosa cell tumours (GCTt...
Campos JR, Breheny P, Araujo RR, Troedsson MH, Squires EL, Timoney PJ, Balasuriya UB.Equine arteritis virus (EAV) is the causal agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids. Some strains of EAV can cause fever, leukopenia, and dependent edema of the limbs, scrotum, and preputium in the acutely infected stallion. We hypothesized that fever and scrotal edema observed during the acute phase of the infection, but not the presence of EAV, have an adverse effect on semen quality. A group of seven stallions were intranasally inoculated with the Kentucky 84 (KY84) strain of EAV. Stallions were monitored for clinical signs of EVA until 42 days...
Chen T, Ward DA.To determine tear volume, turnover rate, and flow rate in ophthalmologically normal horses by use of fluorophotometry. Methods: 12 mares free of ophthalmic disease. Methods: 2 microL of 10% sodium fluorescein was instilled onto 1 eye of each horse, and tear samples were collected via microcapillary tubes from the inferonasal conjunctival culde-sac at 0, 2, 4, 6, 10, 15, and 20 minutes after instillation. Collected tear samples were then measured for fluorescein concentrations with a computerized scanning ocular fluorophotometer. A decay curve plot of concentration changes over time was used to...
Ghosh M, Cho HW, Park JW, Choi JY, Chung YH, Sharma N, Singh AK, Kim NE, Mongre RK, Huynh D, Jiao ZJ, Do KT, Lee HK, Song KD, Cho BW, Jeong D.The athletic abilities of the horse serve as a valuable model to understand the physiology and molecular mechanisms of adaptive responses to exercise. We analyzed differentially expressed genes in triceps brachii muscle tissues collected from Eonjena Taeyang and Jigusang Seryeok Thoroughbred horses and their co-expression networks in a large-scale RNA-sequence dataset comparing expression before and after exercise. High-quality horse transcriptome data were generated, with over 22 million 90-bp pair-end reads. By comparing the annotations, we found that MYH3, MPZ, and PDE8B genes in Eonjena Ta...
Radin MJ, Eubank MC, Weiser MG.Anemia was induced in three groups of horses by moderate or severe acute hemorrhage, or by acetyl phenylhydrazine-induced hemolysis (Groups I, II, and III, respectively). Serial hemograms were done on a multichannel automated blood cell counter with histogram capability. Changes in hematocrit, mean cell volume, erythrocyte number, red cell distribution width (RDW), and standard deviation of erythrocyte volume were examined over time. Significant increases in mean cell volume were first detectable by days 17, 20, and 14 and reached maximum by days 43, 41, and 29, in Groups I, II, and III, respe...
Messenger KM, Davis JL, LaFevers DH, Barlow BM, Posner LP.To describe the pharmacokinetics and adverse effects of intravenous (IV) and sublingual (SL) buprenorphine in horses, and to determine the effect of sampling site on plasma concentrations after SL administration. Methods: Randomized crossover experiment; prospective study. Methods: Eleven healthy adult horses between 6 and 20 years of age and weighing 487-592 kg. Methods: In the first phase; buprenorphine was administered as a single IV or SL dose (0.006 mg kg(-1)) and pharmacokinetic parameters were determined for each route of administration using a noncompartmental model. In the second phas...
Breuhaus BA.Regulatory control of the thyroid gland in horses is similar to other species. Clinical signs of hypothyroidism in adult horses are minimal. Several drugs and physiologic and pathophysiological states can cause circulating thyroid hormone concentrations to be low without actual pathology of the thyroid gland. Thus, nonthyroidal factors must be ruled out before a diagnosis of hypothyroidism can be made. Thyroid hormone supplementation seems to be well tolerated, even in euthyroid horses. Neonatal foals have very high circulating thyroid hormone concentrations, and deficiencies result in signif...
Townson DH, Pierson RA, Ginther OJ.Plasma progesterone concentrations in mares were determined in two experiments during the time that the luteal glands were detectable by transrectal ultrasonography. In both experiments, corpora lutea were classified into two types of morphologies based on their ultrasonic appearance: centrally nonechogenic luteal glands (fluid-filled) and uniformly echogenic luteal glands (non-fluid-filled). In Experiment 1, daily blood samples were taken from horse mares during August through October and May through July. There were no significant effects of season or luteal morphology on progesterone concen...
Xing J, Qi X, Liu G, Li X, Gao X, Bou G, Bai D, Zhao Y, Du M, Dugarjaviin M, Zhang X.In response to muscle injury, muscle stem cells are stimulated by environmental signals to integrate into damaged tissue to mediate regeneration. L-leucine (L-leu), a branched-chain amino acid (BCAA) that belongs to the essential amino acids (AAs) of the animal, has gained global interest on account of its muscle-building and regenerating effects. The present study was designed to investigate the impact of L-leu exposure to promote the proliferation of equine skeletal muscle satellite cells (SCs) on the regulation of RNA networks, including mRNA, long non-coding RNA (lncRNA), covalently closed...
Shaktivesh S, Malekipour F, Whitton RC, Hitchens PL, Lee PV.Fatigue-induced subchondral bone (SCB) injuries are prevalent among athletes due to the repetitive application of high magnitude loads on joints during intense physical training. Existing fatigue studies on bone utilize a standard fatigue test approach by applying loads of a constant magnitude and frequency even though physiological/realistic loading is a combination of various load magnitudes and frequencies. Metal materials in implant and aerospace applications have been studied for fatigue behavior under physiological or realistic loading, however, no such study has been conducted on biolog...
Kerban A, Boerboom D, Sirois J.The time- and gonadotropin-dependent regulation of steroidogenic acute regulatory protein (StAR) has not been characterized in vivo in preovulatory follicles of large monoovulatory species or sexually mature animals. The objectives of this study were to clone equine StAR and describe the regulation of its messenger RNA (mRNA) in equine follicles after the administration of an ovulatory dose of hCG. The screening of an equine follicle complementary DNA (cDNA) library with a mouse StAR cDNA probe revealed two forms of equine StAR that differ only in the length of their 3'-untranslated region (3'...
Wojtasiak-Wypart M, Soma LR, Rudy JA, Uboh CE, Boston RC, Driessen B.Romifidine HCl (romifidine) is an α(2)-agonist commonly used in horses. This study was undertaken to investigate the pharmacokinetics (PK) of romifidine following intravenous (i.v.) administration and describe the relationship between PK parameters and simultaneously recorded pharmacodynamic (PD) parameters. Romifidine (80 μg/kg) was administered by i.v. infusion over 2 min to six adult Thoroughbred horses, and plasma samples were collected and analyzed using liquid chromatography-mass spectrometry. Limit of quantification was <0.1 ng/mL. PD parameters and arterial blood gases were measur...
Strauch S, Wichert B, Greef JM, Hillegeist D, Zeyner A, Liesegang A.The aim of this study was to improve an in vitro system in order to gather optimized information on the digestion of different forages in the horse's upper gastrointestinal tract. Therefore, foregut digestion of several forages was simulated in vitro (Part 1). The effect of different pH values on in vitro fructan degradation of two selected grasses (Part 2) was tested subsequently. Part 1: We hypothesized that our system produces representative results simulating digestive processes in the upper alimentary tract, but neglects microbial fermentation. In vitro digestion of six forages (grass ...
Schramme M, Kerekes Z, Hunter S, Labens R.Tendon injuries are common in athletic humans and horses. Ultrasonography is the diagnostic method of choice in horses with tendon injuries but there is increasing application of magnetic resonance (MR) imaging to monitor and follow-up tendon healing. A core lesion was created in the superficial digital flexor tendon (SDFT) of each forelimb of four horses. One of the four horses was euthanized at 2, 4, 8, and 12 weeks after creation of the lesion. MR examinations of the SDFT were performed immediately post mortem in a 1.5 T Siemens Symphony magnet and compared with histologic findings. Measure...
Galli C, Lagutina I, Duchi R, Colleoni S, Lazzari G.The cloning of equids was achieved in 2003, several years after the birth of Dolly the sheep and also after the cloning of numerous other laboratory and farm animal species. The delay was because of the limited development in the horse of more classical-assisted reproductive techniques required for successful cloning, such as oocyte maturation and in vitro embryo production. When these technologies were developed, the application of cloning also became possible and cloned horse offspring were obtained. This review summarizes the main technical procedures that are required for cloning equids an...
Chateau H, Degueurce C, Denoix JM.Understanding of the biomechanical effects of heel elevation remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. Objective: To quantify the effects of 6 degree heel wedge on the 3-dimensional movements of the 4 distal segments of the forelimb in the walking horse. Methods: Four healthy horses were used. Kinematics of the distal segments was measured invasively with a system based on ultrasonic triangulation. Three-dimensional rotations of the digital joints were calculated by use of a 'joint coordinate system' (JCS...
Burger D, Meuwly C, Marti E, Sieme H, Oberthür M, Janda J, Meinecke-Tillmann S, Wedekind C.Genes of the major histocompatibility complex (MHC) have been shown to influence communication in many vertebrates, possibly with context-specific MHC-correlated reactions. Here we test for MHC-linked female preferences in the polygynous horse (Equus caballus) by repeatedly exposing 19 mares to a group of seven sexually experienced stallions. Each mare was tested four times during two consecutive reproductive cycles, twice during estrus and twice during diestrus. Male plasma testosterone concentrations were determined from weekly blood samples, and equine leukocyte antigen (ELA) class I and II...
Chaudhuri A, Bharadwaj G, Maheshwari R.In the thermophilic fungus Thermomyces lanuginosus, invertase displays an unusual pattern of development: the induced activity begins to diminish even before any substantial quantity of sucrose has been utilized or an appreciable amount of biomass has been produced. Despite this pattern of invertase activity, neither the growth rate nor the final mycelial yield is affected adversely. T. lanuginosus invertase is a thiol protein and the enzyme is active when specific sulfhydryl group(s) is in the reduced state. Measurements of reduced coenzyme and glutathione pools in sucrose-growth mycelia excl...
Pan LG, Forster HV, Bisgard GE, Kaminski RP, Dorsey SM, Busch MA.We studied blood gases in ponies to assess the relationship of alveolar ventilation (VA) to pulmonary CO2 delivery during moderate treadmill exercise. In normal ponies for 1.8, 3, or 6 mph, respectively, partial pressure of CO2 in arterial blood (PaCO2) decreased maximally by 3.1, 4.4, and 5.7 Torr at 30-90 s of exercise and remained below rest by 1.4, 2.3, and 4.5 Torr during steady-state (4-8 min) exercise (P less than 0.01). Partial pressure of O2 in arterial blood (PaO2) and arterial pH, (pHa) also reflected hyperventilation. Mixed venus CO2 partial pressure (PVCO2) decreased 2.3 and 2.9 T...
de Andrade AF, Zaffalon FG, Celeghini EC, Nascimento J, Bressan FF, Martins SM, de Arruda RP.The objective was to verify the relationship between equine semen cryopreservation and changes related to increased lipid peroxidation. Also, addition of autologous or homologous seminal plasma from a stallion with a good freezing response to post-thawed sperm was tested to determine whether it would confer protection. Frozen-thawed sperm were evaluated and allocated into three groups: without plasma addition, and supplemented with either homologous or autologous seminal plasma. All groups were evaluated at 0, 60 and 120 min after incubation at 37 °C. Cryopreservation did not increase plasma ...
Sasaki N, Murata A, Lee I, Yamada H.Horses often suffer reduced intestinal motility after jejunocecostomy. Therefore, accurate evaluation of intestinal motility is important for the prevention, diagnosis and treatment of this condition. The purpose of this study was to evaluate intestinal motility in horses after jejunocecostomy using three different methods, i.e. auscultation, ultrasonography and electrointestinography. Methods: Six healthy thoroughbreds were used in this study. They were subjected to jejunocecostomy. Methods: Bowel sounds in the right paralumbar fossa were assigned a score of 0-3 for intestinal motility evalua...
Aziz DM, Ahlswede L, Enbergs H.The assay of MTT reduction depends on the ability of metabolically active cells to reduce the tetrazolium salt (3[4,5-dimethylthiazol-2-y1]-2,5-diphenyltetrazolium bromide) to formazan. This study was conducted to examine and validate of a simple and less costly MTT test in determining equine sperm viability and compare the efficiency of this test with a flow cytometer. Fresh ejaculates from 11 stallions (warm blood) were included in this study. Semen was diluted to 100 million cells/ml in a Hepes 0.1% BSA. The rates of MTT reduction were measured in microtiter plates after incubation for 1 an...
