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.
Collins SN, Pollitt C, Wylie CE, Matiasek K.Laminitis poses a threat to all horses, and is widely considered as being one of the most important diseases of horses and a global equine welfare problem. The effects of laminitis lead to debilitation, development of pronounced digital pain, and great suffering in the afflicted animal. The precise pathophysiological processes that result in laminitic pain are poorly defined, and hence the delivery of effective palliative care is clinically challenging. Knowledge and understanding of pain states in other animal species may further aid the elucidation of equine laminitic pain mechanisms, guide ...
Muir WW.Pain is a multidimensional sensory phenomenon that has evolved as a protective method for maintaining homeostasis and facilitating tissue repair. Both excitatory and inhibitory physiologic and pathologic mechanisms are involved in its generation and maintenance. Untreated pain and nervous system changes (plasticity) that occur during chronic pain make pain much more difficult or impossible to effectively treat. Therapies directed toward the treatment of pain should be mechanism based and preventative whenever possible. Prospective, randomized clinical trials conducted in horses that suffer fro...
Wullschleger L, Weisse B, Blaser D, Fürst AE.Four radii of different horses were tested in three-point bending and in pure torsion. Detailed finite element (FE) models of these long bones were established by means of computed-tomography (CT) images and tests simulated for both load cases. For the allocation of the local isotropic material stiffness, individual exponential functions were applied whose factor and exponent were determined solely by fitting them to the measured torsional stiffness and bending stiffness of the entire bones. These stiffness functions referring directly to the CT number and having exponents between 1.5 and 2 we...
Schröder W, Klostermann A, Distl O.Intense selection for speed, endurance or pulling power in the domestic horse (Equus caballus) has resulted in a number of adaptive changes in the phenotype required for elite athletic performance. To date, studies in humans have revealed a large number of genes involved in elite athletic performance, but studies in horses are rare. The horse genome assembly and bioinformation tools for genome analyses have been used to compare human performance genes with their equine orthologues, both to retrieve pathways for these genes and to investigate their chromosomal distribution. In this review, 28 c...
Casella S, Giannetto C, Giudice E, Piccione G.The objective of the present study was to evaluate the platelet response to different workload in athletic horse and the influence of hydrocortisone on this response. For this purpose, six Sella Italiana gelding athletic horses, ranging in age from 8 to 10 years and clinically healthy, were subjected to four different exercises: horse-walker, treadmill, obstacle course of 1.00 m and obstacle course of 1.25 m. From all the horses, citrated plasma samples were collected at rest, immediately after exercise and 30 min after the end of the exercise to assess the maximum degree of platelet aggregati...
Dzierzecka M, Czerwinski E.On the basis of a digital analysis of radiograms it was checked if, and to what extent, the extended loading of one of the sides of the body of racehorses leads to differences in the microstructure of the spongy bone of the bilateral pastern bones of the thoracic limbs. The research material consisted of radiograms of the pastern bones of the right and left thoracic limbs of racehorses. On the basis of computer image radiological analysis with the use of the "Trabecula,, programme, a quantative evaluation of the structure of the spongy bone of the pastern bones was conducted. It was noted that...
Asplin KE, Patterson-Kane JC, Sillence MN, Pollitt CC, Mc Gowan CM.Ponies with laminitis associated with insulin resistance and hyperinsulinaemia lack systemic and/or intestinal inflammatory signs, suggesting a different pathogenesis potentially reflected in differing histopathology. Objective: To describe the histological appearance and quantify morphological changes in primary and secondary epidermal lamellae (PEL and SEL) of laminitis lesions from ponies with insulin-induced laminitis. Methods: Equine hoof lamellar tissue was obtained from 4 control ponies and 5 ponies with laminitis induced following infusion of insulin (1036 ± 55 µU/ml) while maintai...
Brink P, Schumacher J, Schumacher J.There is a need for study of a method for restoring a ventrally positioned uterus to a horizontal position involving fertility of mares with delayed uterine clearance. Objective: A ventrally-angled uterus can be elevated to a horizontal position using a laparoscopic technique. Objective: To develop a laparoscopic technique of imbricating the mesometria to elevate the uterus to a horizontal position. Methods: The right and left mesometria of 5 pluriparous mares, all barren for 1-8 years (mean 3.8 years), with a pendulous, ventrally-angled uterus were shortened laparoscopically, by imbrication, ...
Witte TH, Cheetham J, Soderholm LV, Mitchell LM, Ducharme NG.To report (1) the force required on a single laryngoplasty suture to achieve optimal abduction of the left arytenoid cartilage, (2) peak forces experienced by the suture during induced swallowing and coughing, and during 24-hour resting activity in a stall, and (3) peak forces during induced swallowing and coughing after left recurrent laryngeal nerve blockade. Methods: Experimental study. Methods: Horses (n=8). Methods: Each laryngoplasty suture was instrumented with an E-type buckle force transducer to measure the force required for optimal intraoperative left arytenoid cartilage abduction. ...
Kuiper H, Blum N, Distl O.In a 1.5-year-old Oldenburg horse, a clitoris-like structure instead of a penis was identified in the prepuce. The external genital organs did not show any abnormalities at visual inspection except that exteriorization of the penis was not possible, not even under general anesthesia. The horse's owner observed a continuous dripping of urine and a tendency to mild colics beginning 2 weeks after birth. Testosterone concentration was 0.01 ng/ml and therefore under the threshold for geldings, and the horse did not respond to the application of gonadotropin-releasing hormone (GnRH). The inner genit...
Giorgi M, Cuniberti B, Ye G, Barbero R, Sgorbini M, Vercelli C, Corazza M, Re G.Tepoxalin is a non-steroidal anti-inflammatory drug with analgesic, anti-inflammatory, and antipyretic properties and has been recently introduced into veterinary medicine. The aim of this study was to evaluate the pharmacokinetic/pharmacodynamic (PK/PD) profile of tepoxalin to assess whether it would be suitable for clinical use in horses. Six female fasting/fed horses were given 10mg/kg tepoxalin orally in a cross-over study. After administration, tepoxalin underwent rapid and extensive hydrolytic conversion to its carboxylic acid metabolite RWJ-20142. In animals that had been fed, the plasm...
Mykkänen AK, Koho NM, Reeben M, McGowan CM, Pösö AR.Polymorphisms in human lactate transporter proteins (monocarboxylate transporters; MCTs), especially the MCT1 isoform, can affect lactate transport activity and cause signs of exercise-induced myopathy. Muscles express MCT1, MCT4 and CD147, an ancillary protein, indispensable for the activity of MCT1 and MCT4. We sequenced the coding sequence (cDNA) of horse MCT4 for the first time and examined polymorphisms in the cDNA of MCT1, MCT4 and CD147 of 16 healthy horses. To study whether signs of myopathy are linked to the polymorphisms, biopsy samples were taken from 26 horses with exercise-induced...
Franz R, Soliva CR, Kreuzer M, Hummel J, Clauss M.It is assumed that small herbivores produce negligible amounts of methane, but it is unclear whether this is a physiological peculiarity or simply a scaling effect. A respiratory chamber experiment was conducted with six rabbits (Oryctolagus cuniculus, 1.57±0.31 kg body mass) and six guinea pigs (Cavia porcellus, 0.79±0.07 kg) offered grass hay ad libitum. Daily dry matter (DM) intake and DM digestibility were 50±6 g kg⁻⁰·⁷⁵ d⁻¹ and 55±6% in rabbits and 59±11 g kg⁻⁰·⁷⁵ d⁻¹ and 61±3% in guinea pigs, respectively. Methane production was similar for both species (0.2...
Cehak A, Rohn K, Barton AK, Stadler P, Ohnesorge B.Dynamic nasopharyngeal collapse with upper airway obstruction is an important cause of exercise intolerance in performance horses. Its underlying pathophysiology is not fully understood. We hypothesize that head position affects pharyngeal diameter, and thus head position may be a contributing factor to nasopharyngeal obstruction. Fifteen adult healthy horses were subjected to endoscopy and radiography at rest. The pharyngeal diameter was measured at nine different head and neck positions. The effect of sedation and breathing cycle on the pharyngeal diameter was determined, and the relationshi...
Pavone S, Veronesi F, Genchi C, Fioretti DP, Brianti E, Mandara MT.In this study, pathological changes caused by Anoplocephala perfoliata in the ileocecal junction were investigated in 31 regularly slaughtered mixed-breed horses of both sexes. Our results showed a significant relationship between parasite burden and grading of histopathological lesions in the mucosa and submucosa. Hypertrophy of the circular muscle layer was found in infected horses. Moreover, enteric nervous system evaluation showed a significant injury of intestinal nervous elements in the horses with moderate to high parasitism expressed as an increase of degenerative-regressive changes in...
Spriet M, Wisner ER, Anthenill LA, Buonocore MH.Seven isolated equine front limbs were used to establish the normal T1 relaxation time of equine superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), and suspensory ligament (SL) using magic angle magnetic resonance (MR) imaging. MR imaging of the metacarpi was performed with the limbs positioned at 55° (the magic angle) relative to the main magnetic field. Transverse spin-echo proton density and inversion recovery images were acquired. T1 relaxation time was calculated based on ratios of signal intensity determined from the different pulse sequences. T1 relaxation tim...
Nuñez CM, Adelman JS, Rubenstein DI.Although the physiological effects of immunocontraceptive treatment with porcine zona pellucida (PZP) have been well studied, little is known about PZP's effects on the scheduling of reproductive cycling. Recent behavioral research has suggested that recipients of PZP extend the receptive breeding period into what is normally the non-breeding season. Results: To determine if this is the case, we compiled foaling data from wild horses (Equus caballus) living on Shackleford Banks, North Carolina for 4 years pre- and 8 years post-contraception management with PZP (pre-contraception, n = 65 births...
Bugno-Poniewierska M, Dardzińska A, Pawlina K, Słota E.A normal course of meiosis and the associated course of spermatogenesis in males are very significant from the viewpoint of animal breeding, in particular animal reproduction. This takes on special significance when studying late-maturing animals such as horses. The aim of the study was to analyse meiotic cells, with particular consideration of synaptonemal complexes obtained from the testes of young stallions and cryptorchids, based on observations of the X-Y bivalent. The analysis was performed in successive stages of meiotic division using the FISH technique. The greatest diversity and most...
Bach BC, Leal DB, Ruchel JB, Souza Vdo C, Maboni G, Dal Pozzo M, Schlemmer KB, Alves SH, Santurio JM.NTPDase (EC 3.6.1.5) occurs in lymphocytes and plays an important role in immune function, in that hydrolyzes extracellular nucleoside tri- and/or diphosphates to form AMP. Pythium insidiosum causes the disease pythiosis, a pyogranulomatous disease of horses, dogs, cattle, cats and humans. Most antifungal drugs are ineffective against this pathogen, and immunotherapy, a treatment approach that relies on the injection of P. insidiosum antigen, has been successfully used in humans and horses to manage this disease. In this study, we investigated NTPDase activity in lymphocytes from rabbits inocu...
Meghoufel A, Cloutier G, Crevier-Denoix N, de Guise JA.The fiber bundle density (FBD) calculated from ultrasound B-scan images of the equine superficial digital flexor tendon (SDFT) can serve as an objective measurement to characterize the three metacarpal sites of normal SDFTs, and also to discriminate a healthy SDFT from an injured one. In this paper, we propose a shock filter algorithm for the thinning of hyper-echoic structures observed in B-scan images of the SDFT. This algorithm is further enhanced by applying closing morphological operations on filtered images to facilitate extraction and quantification of fiber bundle fascicles. The mean F...
Collins NM, Palmer L, Marr CM.The aim of this study was to establish reference values for a series of conventional two-dimensional (2-D) and M-mode echocardiographic variables in Thoroughbred foals at increasing age intervals. Methods: Nineteen healthy Thoroughbred foals (11 males, 8 females) were examined at 1, 2, 4, 8, 12 and 16 weeks of life. Auscultatory findings were recorded and echocardiographic examinations (2-D and M-mode) were performed. Descriptive statistical analyses, including mean, standard deviation and 95% confidence interval for the means, were used to summarise the data. The relationships between selecte...
Yoon MJ, Roser JF.Leydig cells located in the interstitial space of the testicular parenchyma produce testosterone which plays a critical role in the maintenance and restoration of spermatogenesis in many species, including horses. For normal spermatogenesis, maintaining Leydig cells is critical to provide an optimal and constant level of testosterone. Recently, an anti-apoptotic effect of IGF-I in testicular cells in rats has been reported, but a similar effect of IGF-I on equine Leydig cells remains to be elucidated. If IGF-I also protects stallion testicular cells from undergoing apoptosis, then IGF-I may ha...
Hoogewijs M, De Vliegher S, De Schauwer C, Govaere J, Smits K, Hoflack G, de Kruif A, Van Soom A.Routine semen analysis includes evaluation of concentration combined with seminal volume, morphology and motility. Subjective analysis of these parameters is known to be inaccurate, imprecise and subject to variability. Automated semen analysis could lead to an increased standardization in and between laboratories but for that to happen automated devices need to be validated. A new device, the sperm quality analyzer V equine (SQA-Ve) version 1.00.43, was evaluated for its repeatability and agreement with light microscopy (LM), for raw and extended equine semen. Results were compared with compu...
Brunso L, Segura D, Monreal L, Escolar G, White JG, Diaz-Ricart M.Studies in animal models are useful to understand the basic mechanisms involved in hemostasis and the functional differences among species. Ultrastructural observations led us to predict differences in the activation and secretion mechanisms between equine and human platelets. The potential mechanisms involved have been comparatively explored in the present study. Equine and human platelets were activated with thrombin (0.5 U/ml) and collagen (20 µg/ml), for 90 seconds, and samples processed to evaluate: i) ultrastructural changes, by electron microscopy, ii) actin polymerization and cy...
Celeste CJ, Deschene K, Riley CB, Theoret CL.Wound repair in horse limbs is often complicated by the development of exuberant granulation tissue (EGT) and excessive scarring while body wounds tend to repair uneventfully. EGT resembles the human keloid. While the events leading to keloid formation are not fully elucidated, tissue hypoxia has been proposed as a major contributing factor. The objective of this study was to investigate tissue oxygen saturation in healing full-thickness wounds created on the horse limb and body, using near-infrared spectroscopy. Spectroscopic reflectance data were collected from both anatomic sites at specifi...
Ascenzi P, Santucci R, Coletta M, Polticelli F.Ligand binding to the heme distal side is a paradigm of heme-protein biochemistry, the proximal axial ligand being in most cases a His residue. NO binds to the ferrous heme-Fe-atom giving rise to hexa-coordinated adducts (as in myoglobin and hemoglobin) with His and NO as proximal and distal axial ligands, respectively, or to penta-coordinated adducts (as in soluble guanylate cyclase) with NO as the axial distal ligand. Recently, the ferrous derivative of Alcaligenes xylosoxidans cytochrome c' (Axcyt c') and of cardiolipin-bound horse heart cytochrome c (CL-hhcyt c) have been reported to bind ...
Mayhew IG.Evaluation of horses for eye problems and for suspected impairment of visual acuity often requires a thorough neuroophthalmic examination to be conducted. Along with a full ophthalmic evaluation, the results of such an examination should indicate the likely site of any lesion(s) accounting for blindness, miosis, mydriasis, anisocoria, Horner's syndrome, strabismus, facial paralysis and facial spasm, nystagmus and other signs of vestibular disease, and cerebellar disorders, that may be present. Such a thorough examination with guidance for correct interpretation of findings is given here.
Honnens A, Weisser S, Welter H, Einspanier R, Bollwein H.The objective of this study was to investigate the relationships between uterine perfusion and estrogen, progesterone and the uterine nitric oxide synthase (NOS) system in five trotter mares during the estrous cycle. Color Doppler sonography for measurement of uterine blood flow and collection of blood for determination of plasma estrogen and progesterone concentrations were performed on days 0 (= ovulation), 1, 5, 11 and 15 and daily during estrus (days -1 to -4) of one estrous cycle; endometrial biopsy collection for mRNA expression analysis of NOS and estrogen receptors was performed on day...
Hill EW, McGivney BA, Gu J, Whiston R, Machugh DE.Thoroughbred horses have been selected for traits contributing to speed and stamina for centuries. It is widely recognized that inherited variation in physical and physiological characteristics is responsible for variation in individual aptitude for race distance, and that muscle phenotypes in particular are important. Results: A genome-wide SNP-association study for optimum racing distance was performed using the EquineSNP50 Bead Chip genotyping array in a cohort of n = 118 elite Thoroughbred racehorses divergent for race distance aptitude. In a cohort-based association test we evaluated geno...
Alberghina D, Piccione G, Amorini AM, D'Urso S, Longo S, Picardi M, Tavazzi B, Lazzarino G.This study was designed to examine the influence of sub-maximal exercise on purine and pyrimidine catabolism in horses. Ten horses were initially trained for 12 weeks at the end of which they underwent a standardized exercise test (SET); venous blood samples were taken at rest, 5 and 30 min after the SET. Six untrained healthy horses, from which a blood withdrawal was taken at rest, were used as the control group. Samples were analyzed by HPLC for the simultaneous determination of uric acid, uridine, β-pseudouridine and creatinine in plasma. Glucose and lactate were measured in blood. Trained...
Lohmann KL, Roussel AJ, Cohen ND, Boothe DM, Rakestraw PC, Walker MA.To evaluate the correlation between halftime of liquid-phase gastric emptying (T50), determined with nuclear scintigraphy using technetium Tc 99m pentetate, and absorption variables of orally administered acetaminophen. Methods: 6 mature horses. Methods: Technetium Tc 99m pentetate (10 mCi) and acetaminophen (20 mg/kg of body weight) were administered simultaneously in 200 ml of water. Serial left and right lateral images of the stomach region were obtained with a gamma camera, and T50 determined separately for counts obtained from the left side, the right side and the geometric mean. Power ex...
Valberg SJ.The muscular system of the horse is remarkable in its athletic scope and capacity to adapt to the demands placed on it. Muscular fatigue often causes exercise intolerance in horses as a primary muscular dysfunction or secondary to abnormalities in other integrated systems such as the cardiovascular, respiratory, or skeletal system. This article reviews basic muscular physiology leading to a discussion of the physiologic causes of muscular fatigue. In addition, a review of pathologic muscle disorders such as muscle strains and exertional myopathies that lead to poor performance is provided.
Adams LG, Senior DF.The literal meaning of lithotripsy is the "act of breaking stones." There are two forms of lithotripsy available for use in veterinary medicine: electrohydraulic shock-wave lithotripsy (EHL) and extracorporeal shock-wave lithotripsy (ESWL). With EHL, a shock-wave is generated immediately adjacent to a urolith within the urinary bladder. In dogs, nephroliths or ureteroliths can be successfully treated with ESWL. With ESWL, the shock-waves are generated outside the body and directed toward the urolith.
Piccione G, Rizzo M, Arfuso F, Giannetto C, Di Pietro S, Bazzano M, Quartuccio M.During early post-partum period both neonatal foals and peripartum mares are most susceptible to diseases. The aim of this study was to establish physiologic modifications of leukogram during the first month after foaling in mares and their newborn foals. To this end blood samples were collected from nine mares and nine foals (T0-T10), every three days from the 1st day until the 30th day after foaling. Samples were analysed for white blood cell (WBC) count and differential leucocyte counts. Two-way repeated measure analysis of variance (ANOVA) showed, in postpartum mares WBC showed significant...
Grady JK, Zang J, Laue TM, Arosio P, Chasteen ND.Sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) was used to characterize the H- and L-subunit ratios of several mammalian ferritins and one bacterioferritin. Traditionally, SDS-PAGE has been used to characterize the H- and L-subunit ratios in ferritin; however, this technique is relatively slow and requires staining, destaining, and scanning before the data can be processed. In addition, the H- and L-subunits of ferritin are fairly close in molecular weight (approximately 21,000 and approximately 20,000, respectively) and are often difficult to resolve in SDS-PAGE slab gels. In ...
Willmann C, Budik S, Walter I, Aurich C.A positive influence of altrenogest treatment on a retarded development of the conceptus around the beginning of placentation in mares older than 8 years could be recently demonstrated. In the present study, effects of altrenogest treatment in early-pregnant mares on conceptus development and expression of endometrial and embryonic genes were investigated. Genes were chosen according to a possible involvement in embryo-maternal interaction and embryonic development in the equine species. Mares were treated with altrenogest (0.044 mg/kg bodyweight) or sunflower oil (placebo) from day 5 to 11 af...
Noble GK, Houghton E, Roberts CJ, Faustino-Kemp J, de Kock SS, Swanepoel BC, Sillence MN.Insulin-like growth factor-1 could be a useful marker in the horse for diagnostic, selection, or forensic purposes, provided its physiological regulation is well understood. The objective of this study was to investigate factors, such as acute exercise, fitness training, time of day, sex, and age, that may influence serum IGF-1 in normal, healthy horses. Throughout a 9-wk training program, 6 geldings maintained a mean (+/- SEM) IGF-1 concentration of 302 +/- 29 ng/mL. Moderate or high intensity exercise had no effect on IGF-1 concentrations, when pre- and postexercise values were compared. Ove...
Gaitskell-Phillips G, Martín-Cano FE, Ortiz-Rodríguez JM, da Silva-Álvarez E, Masot J, Redondo E, Gil MC, Ortega-Ferrusola C, Peña FJ.Seminal plasma proteins have important roles in sperm functionality, and different mechanisms including micro-vesicle transport of proteins are involved in the regulation of sperm biology. Due to the role of seminal plasma, we hypothesized that specific proteins present in seminal plasma may be used as discriminant variables with potential to identify stallions producing different quality ejaculates; 10 fertile stallions, with different motility and velocity values (although within normal ranges) were used in this study. Motilities and velocities were studied using computer assisted sperm anal...
Holcombe SJ, Derksen FJ, Berney C, Becker AC, Horner NT.To determine the effect of desensitization of the laryngeal mucosal mechanoreceptors on upper airway mechanics in exercising horses. Methods: 6 Standardbreds. Methods: In study 1, videoendoscopic examinations were performed while horses ran on a treadmill with and without topical anesthesia of the laryngeal mucosa. In study 2, peak tracheal and nasopharyngeal pressures and airflows were obtained from horses during incremental treadmill exercise tests, with and without topical anesthesia of the laryngeal mucosa. A nasal occlusion test was performed on each horse while standing during an endosco...
Palomino Lago E, Jelbert ER, Baird A, Lam PY, Guest DJ.Persistent inflammation is associated with the poor regeneration of musculoskeletal tissues. Embryonic stem cells (ESCs) have an attenuated response to inflammatory cytokines, but there are mixed reports on the response of induced pluripotent stem cells (iPSCs) to inflammation. Horses provide a relevant large animal model for studying musculoskeletal tissue diseases and the testing of novel therapies. The aim of this study was to determine if equine iPSCs are responsive to the inflammatory cytokines IL-1β, TNFα and IFN-γ in their undifferentiated state, or following differentiation into ten...
Obi T, Kabeyama A, Nishio A.In coronary arterial rings isolated from horses, 10(-8)-10(-6) mol/l acetylcholine (ACh) induced concentration-dependent contractions which were potentiated by the removal of endothelium and by pretreatment with L-nitro-arginine (LNAG) or methylene blue (MB). Relatively lower concentrations of ACh (10(-14)-10(-8) mol/l) induced relaxation when the coronary rings were contracted by phenylephrine (PE). ACh-induced contractions in the coronary rings without endothelium were competitively inhibited by each muscarinic subtype selective antagonist in the following order of potency: 4-diphenylacetoxy...
Weiss DJ, Kraemer R, Schmit K.A simple discontinuous Percoll density-gradient technique was adapted for isolation of granulocytes and mononuclear cells from cats, dogs, horses and cattle. Separation was accomplished at low speeds using a standard tabletop centrifuge. Cell purity was 100% for both granulocytes and mononuclear cells and cell viability exceeded 95%. Percent recovery of leukocytes ranged from 69 to 83%.
Pesch S, Bostedt H, Failing K, Bergmann M.Routine semen analysis of stallions is based on light microscopy (LM). However, there are still a number of animals that are subfertile or even infertile not being identified with conventional semen analysis. The objective of this study was to investigate the suitability of transmission electron microscopy (TEM) for advanced fertility diagnosis in stallion. We examined ejaculates of 46 stallions with known fertility. Animals were divided into three different groups: group 1, fertile stallions (pregnant mares> or =70%, n=29); group 2, subfertile stallions (pregnant mares 10-69%, n=14); group 3,...
Vieira LA, Matás C, Torrecillas A, Saez F, Gadea J.Seminal plasma (SP) plays a crucial role in sperm protection and functionality. However, the effect of SP on the sperm cryopreservation is dependent on the stallion and SP composition. The use of epididymal spermatozoa incubated in the presence of SP could help the identification of the components of SP that are able to confer protection upon the spermatozoa during freezing. The aims of this study were (i) to identify SP components involved in the potential protection of epididymal spermatozoa during the freeze-thawing process and (ii) to identify and evaluate the proteins likely related to sp...
Permyakov SE, Khokhlova TI, Uversky VN, Permyakov EA.The triggering of Ca(2+) signaling pathways relies on Ca(2+)/Mg(2+) specificity of proteins mediating these pathways. Two homologous milk Ca(2+)-binding proteins, bovine alpha-lactalbumin (bLA) and equine lysozyme (EQL), were analyzed using the simplest "four-state" scheme of metal- and temperature-induced structural changes in a protein. The association of Ca(2+)/Mg(2+) by native proteins is entropy-driven. Both proteins exhibit strong temperature dependences of apparent affinities to Ca(2+) and Mg(2+), due to low thermal stabilities of their apo-forms and relatively high unfavorable enthalpi...
Ward DS, Fessler JF, Bottoms GD, Turek J.Ponies with electromagnetic blood flow transducers implanted around the main pulmonary and left main coronary arteries, were used to evaluate effects of chronic sublethal endotoxin on cardiac output (CO), stroke volume, and left coronary blood flow (LCBF). Plasma thromboxane (TX), as indicated by TXB2, prostacyclin as indicated by 6-keto-prostaglandin (PG) F1 alpha, and hematologic and blood chemical values also were evaluated. Over 24 hours, 2 groups of ponies were given progressively increasing IV and intraperitoneal doses of Escherichia coli lipopolysaccharide (LPS) at 0, 6, 12, and 18 hour...
Reef VB.Until recently, it was difficult to critically evaluate tendon healing in vivo. Superficial digital flexor tendon injuries were considered healed when the injured tendon was cold, non-painful, adequate time had passed for tendon healing to occur, and no recurrence of the injury was detected when the horse returned to athletic work. This article discusses how ultrasonography has revolutionized the diagnosis, treatment, and management of tendon injuries.
López-Rivero JL, Agüera E, Monterde JG, Vivo J, Rodríguez-Barbudo MV.The mean area and minimal diameter of 3 histochemically determined myofiber types (1, 2A, and 2B; myosin ATPase in acid buffer) were calculated in middle gluteal muscle biopsy specimens from 62 stallions, 47 Andalusians and 15 Arabians, ranging in age from 6 to 12 years. Fourteen Andalusians and 7 Arabians were untrained, and the remainder were actively endurance-trained. The 6-month training schedules involved walking, slow trotting, and cantering. Fourteen Andalusians were moderately endurance-trained, whereas the other 19 Andalusians and 8 Arabians were strongly endurance-trained. Significa...
Manohar M, Bisgard GE, Bullard V, Will JA, Anderson D, Rankin JH.Hemodynamics, myocardial function, and regional myocardial blood flow (MBF) were measured in 6 closed-chest ponies anesthetized with ketamine hydrochloride before (control) and after creation of acute right ventricular systolic hypertension (RVSH) during normoxia and isocapnic hypoxia. The right ventricular (RV) systolic pressure during each RVSH approached 90 mmHg. There were significant alterations in the pattern of total ventricular MBG distribution in favor of the RV. Because RV myocardium received proportionate increments to its endocardium as well as epicardium, it is concluded that auto...
Granier T, Comberton G, Gallois B, d'Estaintot BL, Dautant A, Crichton RR, Précigoux G.We refined the structure of the tetragonal form of recombinant horse L-chain apoferritin to 2.0 A and we compared it with that of the cubic form previously refined to the same resolution. The major differences between the two structures concern the cadmium ions bound to the residues E130 at the threefold axes of the molecule. Taking advantage of the significant anomalous signal (f" = 3.6 e-) of cadmium at 1.375 A, the wavelength used here, we performed anomalous Fourier difference maps with the refined model phases. These maps reveal the positions of anomalous scatterers at different locations...
Reepmeyer JC, Brower JF, Ye H.Equilin-3-sulfate and delta8,9-dehydroestrone-3-sulfate are two isomers found in equine conjugated estrogens that differ in structure only by the position of a double bond in the steroid B-ring. These geometric isomers were not resolved on a C18 column during the analysis of conjugated estrogen drug products by LC-MS using acetonitrile-ammonium acetate buffer as the mobile phase. While no separations of these two isomers were observed on C18 or other alkyl-bonded silica based phases using a variety of mobile phase conditions, partial separations were achieved on phenyl bonded silica phases wit...
Nagy P, Huszenicza G, Reiczigel J, Juhász J, Kulcsár M, Abaváry K, Guillaume D.Factors influencing plasma progesterone concentration were investigated in seven mares. Two-phase logistic curves were fitted (r=0.98) to plasma progesterone concentrations of blood samples collected once daily. In addition to the effect of time (P<0.001), there were differences (P<0.01) among mares in the peak height of the progesterone plateau and in the (area under the curve) AUC. Plasma progesterone concentrations were higher (P<0.001) after a multiple versus single ovulation. There was an effect of season (P<0.001), but no significant effect of luteal morphology. The retrospec...
Oldenhof H, Schütze S, Wolkers WF, Sieme H.Sperm chromatin structure and condensation determine accessibility for damage, and hence success of fertilization and development. The aim of this study was to reveal characteristic spectral features coinciding with abnormal sperm chromatin packing (i.e., DNA-protein interactions) and decreased fertility, using Fourier transform infrared spectroscopy. Chromatin structure in spermatozoa obtained from different stallions was investigated. Furthermore, spermatozoa were exposed to oxidative stress, or treated with thiol-oxidizing and disulfide-reducing agents, to alter chromatin structure and pack...
Thomasy SM, Moeller BC, Stanley SD.To compare the density and binding characteristics of opioid receptor subtypes in horse, rat, and guinea pig cerebral cortex and cerebellum. Methods: Prospective receptor binding study. Methods: Whole brains were obtained from four neurologically normal adult horses during necropsy. Rat and guinea pig brains were obtained commercially. Methods: The cerebellum and cerebral cortex were dissected from each brain, and tissue homogenates prepared. A radioligand binding technique with the highly selective ligands [(3)H]-DAMGO, [(3)H]-U69593, and [(3)H]-DPDPE was used to identify the mu- (mu), kappa-...
Thomas DP, Fregin GF, Gerber NH, Ailes NB.The effects of 5- and 10-wk treadmill exercise training on cardiorespiratory function were evaluated in the horse. Cardiac output (Q), heart rate (HR), and stroke volume (SV), as well as left ventricular (LVP), aortic (AoP), and mean right atrial (RAP) pressures and the peak first time derivative of LVP (LV dP/dtmax), were measured at rest and at five different levels of exercise up to 90% of initial predicted maximal HR (HRmax). Oxygen uptake (VO2) and respiratory exchange ratio (R) were also obtained under the same conditions. At rest, although HR was no different after training, LV dP/dtmax...
Acharya KR, Stuart DI, Phillips DC, McKenzie HA, Teahan CG.Similarities in amino acid sequences, three-dimensional structures, and the exon-intron patterns of their genes have indicated that c-type lysozymes and alpha-lactalbumins are homologous proteins, i.e., descended by divergent evolution from a common ancestor. Like the alpha-lactalbumins, echidna milk, horse milk, and pigeon eggwhite lysozymes all bind Ca(II). Models of their three-dimensional structures, based on their amino acid sequences and the known crystal structures of domestic hen eggwhite and human lysozymes and baboon and human alpha-lactalbumins, have been built. The several structur...
Pascoe PJ, Taylor PM.To determine whether specific dopamine receptor antagonists block alfentanil-induced locomotor stimulation in horses. Methods: Randomized, prospective, crossover experiment. Methods: Eight adult horses (462-604 kg). Methods: Doses of dopamine-1 (D1) (NNC 01-0756) and dopamine-2 (D2) antagonists (eticlopride) were selected in a pilot study prior to a three part, blinded, cross-over study. In part 1, horses received 7.5 micro g kg-1 eticlopride, 5 micro g kg-1 NNC 01-0756 or an equal volume of saline. In part 2, they received both antagonists and in part 3, acepromazine at 0.05 mg kg-1. Locomoto...
Frisbie DD, Nixon AJ.To evaluate potential stimulatory or matrix-sparing effects of insulin-like growth factor 1 (IGF-1), alone or in combination with a corticosteroid, in an interleukin 1 (IL-1)-induced model of cartilage degradation. Methods: Cartilage from the weightbearing surfaces of trochlea and condyles of clinically normal 2-year-old male horses. Methods: Triamcinolone acetonide and IGF-1 effects were evaluated by assessing: matrix responses by sulfated glycosaminoglycan (GAG) assay and [35S]sulfated GAG synthesis; collagen content by hydroxyproline assay; and mitogenic response by [3H]thymidine incorporat...
Healy PJ.Activities of lysosomal hydrolases were measured in the leucocytes of cattle, sheep, goats, horses and pigs. There was high activity of arylsulphatase in leucocytes from cattle, high activities of alpha-fucosidase and beta-glucuronidase in leucocytes from horses and high activity of acid phosphatase in granulocytes from pigs. Within species, arylsulphatase and beta-galactosidase activities were higher in granulocytes than in mononuclear cells, but beta-glucuronidase, phosphodiesterase and alpha-galactosidase activities were higher in mononuclear cells than in granulocytes. Eosinophils of cattl...
Martino NA, Marzano G, Mastrorocco A, Lacalandra GM, Vincenti L, Hinrichs K, Dell Aquila ME.Time-lapse imaging was used to establish the morphokinetics of equine embryo development to the blastocyst stage after invitro oocyte maturation (IVM), intracytoplasmic sperm injection (ICSI) and embryo culture, in oocytes held overnight at room temperature (22-27°C; standard conditions) before IVM. Embryos that developed to the blastocyst stage underwent precleavage cytoplasmic extrusion and cleavage to the 2-, 3- and 4-cell stages significantly earlier than did embryos that arrested in development. We then determined the rate of blastocyst formation after ICSI in oocytes held for 2 days at ...
