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.
Behrendt-Adam CY, Adams MH, Simpson KS, McDowell KJ.In this study, the roles of oestrogen and progesterone in the regulation of oxytocin gene expression in equine endometrium were examined. Anoestrous mares (n=19) were assigned randomly to one of the following treatment groups: control (vehicle control for 1 day; n=3); progesterone (250 mg progesterone per day for 6 days; n=4); oestradiol (5 mg beta-oestradiol 17-valerate per day for 6 days; n=4); oestradiol plus short duration progesterone (5 mg beta-oestradiol 17-valerate per day for 6 days followed by 250 mg progesterone per day for 6 days; n=4); and oestradiol plus long duration progesteron...
Schmid RL, Kato H, Herickhoff LA, Schenk JL, McCue PM, Chung YG, Squires EL.In Expt 1, compact cumulus oocyte complexes (COCs) were matured in: (i) control medium (Hepes-buffered TCM-199 with 10% oestrous cow serum (OCS) + oestradiol, LH and FSH); (ii) Hepes-buffered TCM-199 with 20% follicular fluid; or (iii) control medium containing 250 ng progesterone ml(-1). Mature oocytes were collected by transvaginal aspiration as a positive control for the in vitro maturation (IVM) treatments. Oocytes were fertilized by ICSI and cultured in Menezo's B2 + 5% fetal calf serum (FCS). There were no significant differences among IVM treatments. In Expt 2, oocytes with expanded COC...
Waelchli RO, Jaworski T, Ruddock WD, Betteridge KJ.Equine blastocyst fluid has a lower [Na+], a higher [K+] and a lower osmolality than does normal blood serum. Based on the assumptions that the sodium pump is primarily responsible for fluid accumulation and that ions transported actively into the blastocyst increase blastocyst osmolality above that of the external medium, we hypothesized that the [Na+] and the osmolality of mare uterine fluid are lower than those of blastocyst fluid. Microdialysis and ion chromatography were used to estimate [Na+] and [K+] of uterine fluid. Mares (n=10) were used for in vivo measurements at different stages o...
Stout TA, Lamming GE, Allen WR.In a recent study, continuous administration of oxytocin by subcutaneous minipump to mares from day 8 to 20 after ovulation prevented luteolysis in most of the treated but none of the control mares, indicating a role for oxytocin in cyclical luteolysis in mares. In the present study, measurement of oxytocin concentrations in uterine flushings recovered from nine mares during days 14-18 after ovulation gave values that were many times higher than those measured concurrently in peripheral plasma. Furthermore, intrauterine administration of oxytocin to four mares on day 14 after ovulation stimula...
Scott MA, Liu IK, Overstreet JW, Enders AC.Uterotubal junction tissues (n=12) recovered from young nulliparous mares 4 h after insemination were examined for spermatozoa in situ using scanning electron microscopy. Mares were inseminated before ovulation with semen containing 66-85% morphologically abnormal spermatozoa and approximately 1 x 10(9) progressively motile spermatozoa. Spermatozoa were found in all the tissues and displayed a variety of relationships to the epithelium, depending on regional location, spatial constraints and epithelial surface characteristics. Spermatozoa were most abundant in the epithelial folds on the uteri...
Madill S, Troedsson MH, Alexander SL, Shand N, Santschi EM, Irvine CH.The aim of this study was to investigate the effect of different breeding stimuli on uterine contractility and pituitary oxytocin release in five oestrous mares, in order to design better treatments for mares with defective physical uterine clearance mechanisms. Electrodes and strain gauges were implanted surgically on the uterine myometrium and myometrial activity was monitored with a Grass polygraph. A catheter was placed non-surgically in the intercavernous sinus of each oestrous mare to sample pituitary venous blood and a second catheter was placed in the jugular vein. Continuous sampling ...
Batellier F, Gérard N, Courtens JL, Palmer E, Magistrini M.Milk-based diluents are generally considered efficient for survival of stallion spermatozoa in vitro. However, milk is a complex and variable medium and native phosphocaseinate is a milk component that is more efficient for preservation of sperm motility and fertility, although the mechanisms involved in this protection have not yet been elucidated. The aim of the present study was to characterize the interactions between native phosphocaseinate and equine spermatozoa. No binding between sperm membranes and native phosphocaseinate was observed using indirect immunofluorescent staining or elect...
Causey RC, Ginn PS, Katz BP, Hall BJ, Anderson KJ, LeBlanc MM.The aims of this study were to compare various staining and fixation techniques for endometrial biopsy samples and, thus, to investigate the mucociliary apparatus in endometrium from reproductively healthy mares and mares with delayed uterine clearance. Endometrial samples were collected from the left and right uterine horns of reproductively healthy mares (n=5) and mares with delayed uterine clearance (n=4) during anoestrus, transition, oestrus and dioestrus. Each sample of endometrium was fixed in either Bouin's fixative or formalin, and stained with alcian blue (pH 1.0 or 2.5), periodic aci...
Evans TJ, Ganjam VK, Miller MA, Niswender KD, Krause WJ, Youngquist RS.Endometrial periglandular fibrosis (EPF) has been proposed as a possible aetiology for equine embryonic and fetal loss. However, the pathophysiology of EPF is not well understood. Angiotensin-converting enzyme (ACE) is found in macrophages, endothelium (during angiogenesis) and myofibroblasts at sites of fibrosis in the heart, kidneys, liver and skin in several species. An increase in local tissue ACE-binding activity appears to be a critical event in the initiation and progression of fibrosis in these tissues. The aim of this study was to investigate the correlation between ACE activity in th...
Enders AC, Jones CJ, Lantz KC, Schlafke S, Liu IK.Invasion of trophoblast cells of the chorionic girdle into the endometrium and their subsequent dependence as endometrial cup cells on the maternal vascular system are unique features of equine gestation. This study of exocrine secretion by the endometrial glands and endocrine secretion by the cup cells was initiated to examine the relationships between and the effects of two disparate epithelial cell types sharing the endometrium. Endometrial cups were examined from day 36 to day 83 of gestation by light and electron microscopy, and immunohistochemical and lectin analysis. As the cup cells in...
Shand N, Irvine CH, Turner JE, Alexander SL.Jugular blood samples were collected at 4 h intervals from six mares during an oestrous cycle to study the hormonal events that occur around the time of luteolysis. Blood samples from day 10 (day 0 = ovulation) until day 3 of oestrus were assayed for prostaglandin metabolite 13,14-dihydro-15-keto PGF2alpha (PGFM), oxytocin, prolactin, progesterone and oestrogen conjugates. PGF2alpha (0.5 or 1.5 mg) was administered to six mid-dioestrous mares and the oxytocin and prolactin responses were measured. One to five large (peak > or =2 x nadir) pulses of PGFM, oxytocin and prolactin were detected ...
Chavatte-Palmer P, Duchamp G, Palmer E, Ousey JC, Rossdale PD, Lombès M.Progesterone, oestrogen and glucocorticoid receptor concentrations in the uterus and mammary glands of pregnant mares during mid- to late gestation (from day 150 of gestation to term) were measured by binding assays to investigate the hormonal mechanisms involved in pregnancy maintenance and lactation. Uterine progesterone receptor concentrations did not increase significantly with increasing gestational age (from 67.8 +/- 13.7 to 126.1 +/- 48.7fmol mg(-1) protein), whereas oestrogen receptor concentrations were significantly higher in pregnant mares (271.7 +/- 28.9 fmol mg(-1) protein) than i...
Malikides N, Kessell A, Hodgson JL, Rose RJ, Hodgson DR.Evaluation of erythropoietic regeneration in horses is difficult unless serial bone marrow aspirates are performed. To investigate the acute and chronic erythropoietic regenerative response of equine bone marrow following acute removal or loss of blood, sequential bone marrow aspirates over 4 weeks were taken from the sternum of five horses from which 20 ml kg(-1)of blood had been removed. We found that the total number of erythroid cells counted (expressed as a percentage of the total number of erythroid and myeloid cells counted) expanded initially by 13.7 per cent within 3 days after blood ...
Corcoran BM, Jarvis S, Hahn CN, Mayhew IG.The autonomic innervation of the mammalian respiratory system is complex, and involves a wide variety of peptide and non-peptide neurotransmitters which will have an important role in normal laryngeal function and the response to disease. This innervation has been partially described in the horse airway and lung, but there is no information on the equine larynx. This paper describes the expression and distribution of nerve fibres immunoreactive for vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), substance P (SP) and the adrenergic enzymatic marker dopamine beta-hyd...
Hoyt DF, Wickler SJ, Cogger EA.Using published values for twelve species of birds and mammals, we investigated the effects of limb length and running speed on time of contact and step length. In addition, we measured the time of contact in horses trotting up a 10 % incline and when carrying a load averaging 19 % of their body mass. From these values, we calculated stride period and step length. Our analysis of the interspecific data yielded the following relationship between time of contact (t(c) in s) and leg length (L in m) and running speed (v in m s(-)(1)): t(c)=0.80L(0.84)/v(0.87) (r(2)=0.97). Both exponents in this re...
Cerón JJ, Tecles F, Espín JC.Effects of seven different blood diluents (distilled water, Triton X-100, saponin, isotonic saline solution, pH 7.5 and 8 phosphate buffers and bovine serum albumin) and two chromophores: 5, 5'-dithiobis 2-nitrobenzoic acid (DTNB) and 2,2'-dithiodipyridine (2- PDS) on blood cholinesterase determination in four domestic species (cow, sheep, goat and horse) are described and compared. Haemolytic diluents (distilled water, Triton X-100 and saponin) gave the best precision results when fresh blood was assayed. However, Triton X-100 induced lower ChE activity values in horses, and saponin yielded v...
Todi F, Mendonca M, Ryan M, Herskovits P.The origin of caffeine detections in equine serum and urine after theophylline administrations was examined. Three different preparations containing theophylline were administered to standardbred mares. Both blood and urine samples were collected. Caffeine was detected and quantified in theophylline administration samples by high performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). Further in vitro analysis showed that caffeine metabolites were not detected when caffeine, or caffeine-containing products, were added to urine. Data derived from ...
Pardoe CH, Wilson AM.Hoof wall cracks need mechanical stabilisation to allow healing. Common techniques are fixation with screws, wires and plates or bonding of a patch across the crack. An in vitro system to determine the shear properties of equine hoof crack repairs is described. The force and displacement at yield, stiffness and ultimate force were determined for 4 repair techniques based on an acrylic material, polyurethane patch attached with cyanoacrylate adhesive, steel plate attached with screws and a transverse metal bar cut into the hoof wall. The cyanoacrylate bonded patch repair had lower values for al...
Mohr E, Krzywanek H, Pinkowski W.Monitoring training by measuring blood lactate content is a well-known procedure in sports physiology. Because of the difficulties in standardizing a test procedure in field studies, this method is fraught with considerable problems when applying it to race horses. The aim of the present study was to develop a test procedure which is able to give evidence about the training state of different race horses after nonidentical test-loads. Under almost identical environmental conditions, the level of blood lactate was determined in five trotters which were kept in training. Immediately after the si...
Perkins NR.This article reviews therapies and strategies commonly used to treat diseases of the mare's genital tract and modulate the reproductive cycle of the mare. Many reproductive treatments are based on historical use and empirical evidence rather than well controlled clinical studies. This article attempts to present practical information in a summary form while highlighting the need for continued research documenting the efficacy and safety of reproductive therapies.
Magee AA, Galuppo LD.To determine the bursting strength of ventral median abdominal incisions closed by either simple continuous or inverted cruciate suture patterns. Methods: Experimental. Methods: Twelve equine cadavers. Methods: A 25 cm ventral median incision was made through the linea alba and a 200 L polyurethane bladder was placed within the abdomen. Either a simple continuous or an inverted cruciate pattern using 3 polyglactin 910 with a bite size and suture interval of 1.5 cm was used to close linea incisions. Closure time was recorded for each pattern. The bladder was inflated with air at 40 L/min, and t...
Shipstone , Mueller , Bettenay , Mason , Friend .The macroscopic and microscopic effects following the intradermal injection of the mast cell degranulator compound 48/80 were investigated in horses. It was found that a 1000 μg mL-1 solution of compound 48/80 could be used as an alternative to histamine as a positive control in equine intradermal allergy tests. An inflammatory cell infiltration was noted on histological examination, following compound 48/80 injection. This inflammatory cell pattern was similar to that noted for Type-I hypersensitivity.
Aurich C, Gerlach T, Aurich JE, Parvizi N.Modulation of reproductive functions is one of the multiple effects of growth hormone (GH). To investigate effects of reproductive functions on GH release in the horse, plasma GH concentrations in ovary-intact (n = 7) and ovariectomized (n = 8) mares during the anovulatory and breeding seasons and in pregnant mares (n = 6) at various stages of gestation were determined. To analyze an opioidergic regulation of GH release, repeated blood samples were taken over 3 h, and mares were injected with the opioid antagonist naloxone (0.5 mg/kg i.v.) or saline. GH was determined by RIA with an antiserum ...
Gastal EL, Bergfelt DR, Nogueira GP, Gastal MO, Ginther OJ.The effects of several doses of progesterone on FSH and LH concentrations were used to study the role of the gonadotropins on deviation in growth rates of the two largest follicles during the establishment of follicle dominance. Progesterone was given to pony mares at a daily dose rate of 0 mg (controls), 30 mg (low dose), 100 mg (intermediate dose), and 300 mg (high dose). All follicles > or = 6 mm were ablated at Day 10 (Day 0 = ovulation) to initiate a new follicular wave; prostaglandin F(2alpha) was given to induce luteolysis, and progesterone was given from Days 10 to 24. The low dose ...
Hoffmann B, Landeck A.To gain further information on gonadal function of the stallion, concentrations of testicular steroids in blood plasma (bpl) and seminal plasma (spl) and their distribution in the ejaculate were determined. Blood and semen samples from a total of 11 stallions were collected from November to July. Estrone (E1), estrone sulfate (E1S), estradiol-17beta (E2beta) and testosterone (T) were determined in bpl and spl, and in addition androstenedione (A), dehydroepiandrosterone (DHEA) and 5alpha-dihydrotestosterone (5alpha-DHT) were measured in spl. At certain points of time, aliquots of an ejaculate w...
Murabayashi H, Hondo E, Kitamura N, Furuoka H, Taguchi K, Nambo Y, Yamada J.One of the most attractive characteristics of a horse testis is the change of the weight during development. As the testicular weight changes and the number of Leydig cells decreases, pigments appear in interstitial tissues. In the present study, the characteristics of the pigments found in the interstitial tissues were examined histochemically and ultrastructurally. Specific stainings indicated that the pigmented granules showed almost all of the histological and histochemical characteristics of ceroid or ceroid-like pigment. The cells showed positive reaction for acid phosphatase while the p...
McCutcheon LJ, Geor RJ, Ecker GL, Lindinger MI.This study examined sweating responses in six exercise-trained horses during 21 consecutive days (4 h/day) of exposure to, and daily exercise in, hot humid conditions (32-34 degrees C, 80-85% relative humidity). On days 0, 3, 7, 14, and 21, horses completed a standardized exercise test on a treadmill (6 degrees incline) at a speed eliciting 50% of maximal O(2) uptake until a pulmonary artery temperature of 41.5 degrees C was attained. Sweat was collected at rest, every 5 min during exercise, and during 1 h of standing recovery for measurement of ion composition (Na(+), K(+), and Cl(-)) and swe...
Macdonald DG, Fretz PB, Baptiste KE, Hamilton DL.The anatomy of the internal carotid and maxillary arteries was examined using angiography, subtraction angiography and arterial cast preparations in three horses. Subtraction angiography was superior to angiography in demonstrating the anatomy of the occipital, external ophthalmic, ethmoidal and palatine arteries. In three horses manipulation of the internal carotid and occipital arteries during angiography resulted in vasospasm which prevented filling of these vessels with contrast. Direct arterial blood pressure measurements of the maxillary artery impinging on the guttural pouches was measu...
da Costa RP, Branco V, Pessa P, Silva JR, Ferreira-Dias G.Steroid hormones act via specific receptors, and these play an important physiological role in the ovary. The objective of this study was to evaluate the cellular distribution of progesterone receptors and their staining intensity in different equine luteal structures during the breeding season, as well as their relationship to luteal cell composition, cell proliferation pattern and plasma progesterone (P4) concentration. There was an increase in proliferating cell nuclear antigen (PCNA) expression in large luteal cells from the corpus hemorrhagicum (CH) to mid-luteal phase, followed by a decr...
Eisenhauer KM, Roser JF.A stallion testicular cell incubation system was developed and used to investigate the regulation of steroidogenesis in stallion testes. Cells isolated from testes of 2- to 4-year-old stallions (n = 6) were cultured for 12 hours in a defined medium with and without varying doses of lipoprotein, equine luteinizing hormone (eLH), human chorionic gonadotropin (hCG), equine follicle-stimulating hormone (eFSH), and/or equine prolactin (ePRL). Estrogen conjugate (EC), testosterone (T), and estradiol-17 beta (E2) production were determined by RIA. Increasing doses of lipoprotein significantly (P <...
Moens VY, Gootjes P, Lagerweij E, van Dijk P.The use of pulse oximetry for on-line monitoring of oxygen saturation of arterial blood using a probe on the nasal septum is described in the horse. When compared to the results of blood gas analysis an excellent correlation between the two methods for measuring oxygen saturation is found. Nevertheless a discrepancy between the values for oxygen saturation provided by either method is found. This can lead to misinterpretation of oxygen saturation values generated by the pulse oximeter. The cause of this discrepancy is not clear but differences in measuring principle, presence of dyshemoglobins...
Sivertsen T.Reduced glutathione (GSH), per cent methaemoglobin and haemolysis were measured in physiologic saline suspensions of erythrocytes from sheep, goat, cattle, horse, swine and man; incubated for 24 hours at 37 degrees with and without copper sulphate (0,5 and 10 micrograms Cu/ml suspension). Formation of Heinz bodies was studied in similar experiments with sheep and swine cells only. Generally, GSH depletion developed first, followed by methaemoglobinemia and Heinz bodies, while haemolysis was limited. Both spontaneous and copper-induced GSH depletion was slow in swine erythrocytes compared to ot...
Lanier CJ, Taintor JS, Christopherson PW, Spangler EA.Acidemia in sick or injured horses is often due to lactic acid accumulation. Alterations in platelet function and hemostasis are among numerous deleterious effects caused by decreased physiologic pH. Objective: We aimed to evaluate the effect of hyperlactatemia and resultant acidemia on platelet aggregation in equine whole blood using impedance aggregometry. Methods: Platelet aggregation was measured using the Multiplate analyzer in whole blood from 34 healthy horses at baseline and after in vitro addition of lactic acid to adjust the pH. Platelet aggregation of each sample was quantified by t...
Dawson J, Lees P, Sedgwick AD.The direct effects of four non-steroidal anti-inflammatory drugs (NSAIDs) on equine polymorphonuclear (PMN) and mononuclear (MN) leucocyte movement were investigated using two in vitro assay systems. The Boyden chamber microfilter technique measures both chemokinetic and chemotactic locomotion, and the agarose microdroplet assay measures solely chemokinesis. Zymosan-activated plasma (ZAP) and the synthetic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) were used as standard chemoattractants for PMN and MN leucocytes, respectively. The actions of six concentrations of each NSAID, indome...
Garcia Lascurain AA, Sumano Lopez H, Steffey EP, Santillán Doherty P, Hernandez EN.To characterize behavioral and physiological responses to short-term, unsupplemented intravenous (IV) anesthesia in healthy horses at high altitude (2240 m), and to test the hypothesis that the dose of butorphanol modifies the response of the horse to propofol anesthesia following xylazine pre-medication. Methods: Randomized prospective butorphanol dose cross-over experimental design. Animals Eight healthy horses, 13 +/- 6 (mean +/- SD) years of age, and weighing 523 +/- 26 kg. Methods: Each horse was anesthetized three times with at least 3 weeks between each anesthesia. After collecting pre-...
Gentry PA, Zareie M, Liptrap RM.The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with f...
Ganeshpurkar A, Singh R, Kumar D, Gutti G, Sardana D, Shivhare S, Singh RB, Kumar A, Singh SK.Machine learning (ML), an emerging field in drug design, has the potential to predict toxicity, shape-based analysis of inhibitors, scoring function (SF) etc. In the present study, a homology model, docking protocol, and a dedicated SF have been developed to identify the inhibitors of horse butyrylcholinesterase (BChE) enzyme. Horse BChE enzyme has homology with human BChE and is a substitute for the screening of inhibitors. The developed homology model was validated and the active site residues were identified from Cavityplus to generate grid box for docking. The validation of docking invol...
Lorenzo-Figueras M, Preston T, Ott EA, Merritt AM.To evaluate the effect of ingestion of a high-carbohydrate versus a high-fat meal on relaxation of the proximal portion of the stomach and subsequent gastric emptying in horses. Methods: 6 healthy adult horses. Methods: The study consisted of 2 phases. In phase I, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal (0.5 g/kg) of identical volume, caloric density, and protein content. In phase II, meals consisted of a commercial sweet feed meal (0.5 g/kg) or this meal supplemented with corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Proximal...
Eydt C, Geburek F, Schröck C, Hambruch N, Rohn K, Pfarrer C, Staszyk C.Aspiration of equine sternal bone marrow is required for the cultivation of bone marrow-derived multipotent mesenchymal stromal cells (BM-MSCs) for regenerative therapies. For bone marrow aspiration as well as for MSC cultivation, there is a need to optimize techniques and protocols to enhance MSC harvest at minimized culture times. In a comparative study bone marrow aspirates from sternebra 4 and 5 were collected at two different positions within the sternebrae, either from 10 mm or from 30 mm dorsal from the ventral margin of the sternebrae. Accuracy of the puncture depth was confirmed by ...
Agüera EI, Rubio MD, Vivo R, Santisteban R, Muñoz A, Castejón F.A study was performed on Andalusian horses in order to assess the response of heart rate and various blood parameters to training. Two tests were performed, at two and four months of training respectively. Exercise schedules were of increasing intensity, over a distance of 1000 meters. Speed was progressively increased, from 4 m/s to 8.5 m/s, over four exercise stages. In both tests, a recovery period of 5 min followed each stage. Sample collection (by puncture of the external jugular vein) was performed with the animals at rest, within the first minute after each exercise stage, and at 10, 15...
Araki M, Ohtaki T, Kimura J, Hobo S, Taya K, Tsunoda N, Taniyama H, Tsumagari S, Nambo Y.Immunohistochemical investigations of the expression of surfactant protein A (SP-A) and surfactant protein D (SP-D) in the uterine and placental tissues of 13 pregnant mares were performed using anti-horse monoclonal primary antibodies. Strong positive reactions for both SP-A and SP-D were observed in the trophoblasts in the microcotyledons of the placentae at 182 to 314 days of gestation; in uterine glandular epithelial cells, faint-to-weak reactions were observed during gestation. This study describes, for the first time, the changes in the SP-A and SP-D expression levels in the endometrium ...
Köhne M, Unruh C, Böttcher D, Tönissen A, Ulrich R, Sieme H.Uterine pathologies are the most common causes of infertility in mares. This study aimed to establish an ex vivo blood-perfused model for equine uteri and investigate the possible effects of different cycle stages (estrus, diestrus and anestrus) on the applicability of the model. Uteri (n = 13) were collected at an abattoir, flushed with preservation solution, transported to the laboratory on ice, and isolated perfused with autologous blood for 6 h (n = 12). For negative control, one uterus was handled as described but left without perfusion for 6 h. The cycle stage was determined by ex...
Annandale A, Stroehle RM, Schulman ML, Sibeko-Matjila KP, Fosgate GT, Handler J, Vemming DC, Clift SJ.Persistent breeding-induced endometritis (PBIE) or delayed uterine clearance (DUC) are major causes of mare subfertility. Oxytocin and its receptor are thought to play significant roles in the pathogenesis of DUC but the specific roles of oxytocin receptor (OR) distribution and gene expression remain undefined. In this study both OR distribution and gene expression in the endometrium, myometrium and cervix during both luteal and non-luteal phases in non-pregnant mares (n = 27) of differing age (young: 2-9 years, n = 17; old: > 10 years, n = 10) and endometrial biopsy score were ...
Davis K, Carter R, Tully T, Negulescu I, Storey E.To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Methods: Twenty-six raptors, ten dogs, three cats, and one horse. Methods: Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, US...
Manohar M, Hassan AS.To ascertain whether costal diaphragm engages in ammonia and lactate production (like limb muscles) during high-intensity short-term exercise, experiments were carried out on six healthy trained ponies in which phrenic venous catheters had been implanted 5-9 days earlier. Simultaneous anaerobically obtained blood samples from abdominal aorta and the phrenic vein at rest and during 4 min of exertion at 32 km/h and at a 7% grade were analyzed for blood-gas variables as well as lactate and ammonia concentrations using standard procedures. At rest, heart rate was 47 +/- 4 beats/min and the diaphra...
Björkman N, Nielsen P, Hornshøj Møller V.Formaldehyde was removed from embalmed animal cadavers by pumping ethanol (20%) through the pleural and peritoneal cavities of 4 goats, 4 cows and 4 horses. The goats were percolated intermittently for 7 days and the large animals continuously for 72 h. Just after opening the body cavities, samples of air close to the organs were collected and analyzed for formaldehyde using a spectrofluorimetric method. The concentration of formaldehyde in the air samples was in goats 0.45 +/- 0.44 microgram/l (mean +/- SD), cows 0.42 +/- 0.29 microgram/l and horses 0.43 +/- 0.25 microgram/l.
Rangel-Sánchez IY, Salas-Treviño D, Soto-Domínguez A, Garza-Rodríguez OI, Saucedo-Cárdenas O, Zapata-Benavides P, Zarate-Ramos JJ....The Wilms' tumour gene (WT1) has previously been described as an oncogene in several neoplasms of humans, including melanoma, and its expression increases cancer cell proliferation. Recent reports associate the expression of the PPARβ/δ gene (peroxisome proliferator-activated receptor beta/delta) with the downregulation of WT1 in human melanoma and murine melanoma cell lines. The aim of this work was to analyse the expression of WT1 and its association with PPARβ/δ in samples of healthy and melanoma-affected skin of horses by immunohistochemistry. WT1 protein expression was detected in hea...
Peck KE, Matthews NS, Taylor TS, Mealey KL.To compare serum disposition of sulfamethoxazole and trimethoprim after IV administration to donkeys, mules, and horses. Methods: 5 donkeys, 5 mules, and 3 horses. Methods: Blood samples were collected before (time 0) and 5, 15, 30, and 45 minutes and 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 8, 10, and 24 hours after IV administration of sulfamethoxazole (12.5 mg/kg) and trimethoprim (2.5 mg/kg). Serum was analyzed in triplicate with high-performance liquid chromatography for determination of sulfamethoxazole and trimethoprim concentrations. Serum concentration-time curve for each ani...
Freestone JF, Shoemaker K, Bessin R, Wolfsheimer JK.Twenty-three well-conditioned ponies were evaluated for insulin and glucose response following oral glucose administration (1 g/kg bodyweight [bwt] as a 20 per cent solution). Ponies were defined as normal if total insulin secretion (TIS) was less than 149 mu iu/ml h and the glucose concentration was below 11.1 +/- 0.11 mmol/litre (200 +/- 2 mg/dl) at all times following oral glucose administration. When glucose concentrations were maintained below 11.1 +/- 0.11 mmol/litre, the area under the glucose curve (TG) was less than 17.4 mmol/litre/h (314 mg/dl/h). The ponies were assigned to four gro...
Dees WL, Sorensen AM, Kemp WM, McArthur NH.Immunohistochemical localization of the decapeptide gonadotropin releasing hormone (GnRH) in neural structures in the pony brain and infundibulum (INF) was conducted at the light-microscopic level. This procedure utilized an antiserum generated against GnRH conjugated to bovine serum albumin. In the rostral INF, GnRH was distributed mainly in the external layer, with greatest concentrations adjacent to the long capillary loops of the hypophyseal portal system. The intermediate portion of the INF contained the hormone throughout the external layer, especially in the dorsolateral regions just ve...
Gueguen L, Lerch N, Grandgeorge M, Hausberger M.Tactile perception is involved in a variety of contexts (adaptations to climatic conditions, protection of the body against external dangers…) and is as important as the other sensory modalities for the survival of an individual. This tactile modality has been particularly well studied in humans, revealing high individual variations modulated by a variety of intrinsic and extrinsic factors such as age, sex, pathological disorders, or temperament. Tactility is also involved in animals' social lives, although there are disparities between species. For example, social tactile contact among hors...
Snow DH, Martin V.To investigate the claim that equine erythrocytes released from the spleen are older cells than those found at rest in the circulation, the 2,3, diphosphoglycerate (2,3 DPG), adenosine triphosphate (ATP) and creatine concentration of erythrocytes before and following splenic emptying were examined. Normal values for thoroughbreds (43) and ponies (10) at rest were established. Following either exercise or intravenous injection of adrenaline in six thoroughbreds, there was an increase in erythrocyte creatine content and a decrease in ATP concentration. Exercise produced a slight increase in 2,3 ...
Bardell D, Mosing M, Cripps PJ.Arterial hypoxaemia is common in anaesthetised horses, but little information exists regarding restoration of arterial oxygen tension (PaO ) during recovery from anaesthesia, or if intra-operative management factors exert any longer-term effect. Objective: To evaluate PaO in horses recovering from general anaesthesia up to 1 h after resuming standing. Methods: Prospective observational clinical cohort study. Methods: Systemically healthy adult horses undergoing inhalational general anaesthesia for elective surgical procedures were studied. Arterial blood samples were obtained anaerobically pr...
Ferreira JC, Meira C, Papa FO, Landin e Alvarenga FC, Alvarenga MA, Buratini J.Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were remov...
Bailey SR, Cunningham FM, Elliott J.Uptake of 5-hydroxytryptamine (5-HT) into platelets is an important mechanism by which low plasma concentrations are maintained, and platelet activation may therefore result in significant release of this vasoconstrictor. The present study examined the kinetics of active uptake of radiolabelled [3H]5-HT by washed equine platelets in vitro, and investigated the effects on this process of 4 other naturally occurring monoamines which may be released from the caecum in conditions of carbohydrate overload. The release of [3H]5-HT by platelets was also studied, since platelet accumulation and activa...
Dart AJ, Snyder JR, Julian D, Hinds DM.The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfu...
Palmer E, Jousset B.Following an initial observation period of 13 days when plasma progesterone levels were determined, synchronization of oestrus and ovulation was investigated in thirty-three mares treated with a prostaglandin analogue ('Equimate') and HCG. Two courses of treatment were given 8 days apart and each consisted of a single intramuscular injection of Equimate (250 mug) followed 6 days later by an intramuscular injection of HCG (2500 i.u.). The first course was designed to remove all luteal tissue and to induce ovulation of any follicles that developed in response to the withdrawal of progesterone. T...
Beadle RE, Guthrie AJ, Kou AH.A density-corrected ultrasonic pneumotachometer designed specifically for horses (UF202) was evaluated and characterized with the aid of a custom-built apparatus. UF202 provided voltage outputs for airflow through and gas density within the flowhead. Baseline stability for flow channel output (VUF202) was or = 0.9976). Under optimal conditions, VUF202 accuracy was determined to be +/- 1.00% FS and repeatability was +/- 0.78% FS. VUF202 resolution was 24 ml/s. The rise time for VUF202 was 18 ms, and the -3-dB point was 18 Hz; digital compensation provided a flat frequency response to 32 Hz. VU...
