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.
Stott ML, Osburn BI.Long-term equine lymphocyte cultures were initiated and maintained in continuous culture with medium containing recombinant human interleukin-2. Cultures were successfully maintained with lectin activation signals and recombinant human interleukin-2 or with recombinant human interleukin-2 alone. All cell cultures that were characterized had a T-lymphocyte phenotype and had lectin-dependent or -independent cytotoxicity directed to various cell types. These findings demonstrate that long-term equine T-lymphocytes cultures can be initiated and maintained easily.
Barker BB, Stannard AA, Maibach HI.Epidermal cell labeling index and cell renewal time were estimated in 8 adult horses, using autoradiography after [3H]thymidine was given intradermally. The mean labeling index was 1.45 +/- 0.47%, and the mean cell renewal time of the viable epidermis was approximately 17 days.
Swanson CR, Muir WW.The influence of positive end-expiratory pressure (PEEP) on the alveolar-arterial O2 tension difference [P(A-a)O2], physiologic right-to-left shunt fraction, physiologic dead space-to-tidal volume ratio, and hemodynamic variables was studied in halothane-anesthetized horses maintained in dorsal recumbency during controlled ventilation. Dobutamine was used to minimize the adverse cardiovascular consequences of PEEP. Six adult horses were anesthetized, using xylazine (2.2 mg/kg of body weight, IM), guaifenesin (50 mg/kg, IV), thiamylal Na (4.4 mg/kg, IV), and halothane (1.5 to 2% inspired) in 10...
Allen D, Korthuis RJ, Clark S.A pump-perfused extracorporeal digital preparation was used to evaluate blood flow, arterial pressure, venous pressure, isogravimetric capillary filtration coefficient, capillary pressure, and vascular compliance in six normal horses. From these data, pre- and postcapillary resistances and pre- and postcapillary resistance ratios were determined. Vascular and tissue oncotic pressures were estimated from plasma and lymph protein concentrations, respectively. By use of the collected and calculated data, tissue pressure in the digit was calculated using the Starling equation. In the isolated equi...
Stolk PW, Firth EC.Intra-osseous pressure was measured in the third metatarsal bone of 8 pony foals at the age of 1, 3, 6 and 26 weeks of age, and on one occasion in the third metatarsal bone of 5 ponies aged 1-5 years; the animals were under general anesthesia and in lateral recumbency. Saphenous venous pressure and lateral superficial plantar metatarsal arterial pressure were also monitored throughout the procedure. There were no statistically significant changes in the epiphyseal, diaphyseal, venous or arterial pressures with increasing age of the foals. There was no statistically significant difference betwe...
Sojka JE, Adams SB, Lamar CH, Eller LL.Effect of butorphanol, pentazocine, meperidine, and metoclopramide on jejunal and pelvic flexure myoelectric and mechanical activity in 4 female ponies was investigated. The agent to be tested or saline solution was administered IV at the start of a 6-hour recording trial. In the jejunum, duration between activity fronts of regular spiking activity, defined as the length of the migrating myoelectric complex (MMC), was measured. The average duration of the MMC during control trials was 150 +/- 46 minutes. The average duration of the MMC after meperidine, butorphanol, pentazocine, and metoclopra...
Jernigan AD, Wilson RC, Booth NH, Hatch RC, Akbari A.In steers, horses and dogs, the comparative pharmacokinetics of yohimbine were determined using model-independent analysis. The intravenous dose of yohimbine was 0.25 mg/kg of body weight in steers, 0.075 or 0.15 mg/kg in horses, and 0.4 mg/kg in dogs. The mean residence time (+/- SD) of yohimbine was 86.7 +/- 46.2 min in steers, 106.2 +/- 72.1 to 118.7 +/- 35.0 min in horses, and 163.6 +/- 49.7 min in dogs. The mean apparent volume of distribution of yohimbine at steady state was 4.9 +/- 1.4 L/kg for steers, 2.7 +/- 1.0 to 4.6 +/- 1.9 L/kg for horses, and 4.5 +/- 1.8 L/kg for dogs. The total ...
Sairam MR, Yarney TA, Bhargavi GN, Sanford LM.A membrane preparation from the testis of maturing Dorset-Leicester-Suffolk sheep, capable of discriminating pituitary LH (lutropin) from placental gonadotropins human choriogonadotropin (hCG) and equine choriogonadotropin is described. Maximum binding of 125I-oLH (ovine lutropin) to the testicular receptors occurred at 4 degrees C in a rapid manner, attaining equilibrium in 12-16 h. Under such optimal conditions, only unlabeled ovine LH or the structurally identical bovine LH effectively competed for receptor occupation. Other highly purified pituitary LH preparations from rat and human pitui...
Johansson J, von Bahr-Lindström H, Jeck R, Woenckhaus C, Jörnvall H.The primary structure of the mitochondrial form of horse liver aldehyde dehydrogenase has been determined, utilizing peptide analyses and homology with other enzyme forms. The subunit exhibits N-terminal heterogeneity in size similar to that for the corresponding human mitochondrial protein, the longest form having 500 residues. Catalase was identified as a contaminant of the preparations. All four pairs within a set of aldehyde dehydrogenases can now be compared, including the same two species variants (horse and human) for both the cytosolic and mitochondrial enzyme, revealing characteristic...
Smyth GB.Lengths of small intestine, caecum, ascending colon and descending colon were measured in intestinal tracts from 103 foetuses, foals and adult horses. Intestinal tracts from 21 of the horses were measured at varying intervals after death. Total intestinal length increased markedly from mid-gestation to one year of age, then showed little increment up to 35 years. Small intestinal length increased most rapidly in the first month of life. Caecal length increased most rapidly from one to six months and length of ascending colon increased most rapidly between one week and one year. Descending colo...
Meistrich ML.The problem of extrapolating effects of reproductive toxins on experimental animals to predict the doses that would produce infertility in human males is discussed using published data on effects of testosterone and estradiol on sperm production in the rat, rabbit, rhesus monkey, ram, stallion, and humans. This analysis indicates that calculation of the dose of testosterone that reduces human sperm counts by a given percentage is best done using the dose administered to laboratory animals expressed on the basis of body weight, as opposed to some other parameter such as body surface area. A sur...
Evans DL, Rose RJ.A rapid incremental treadmill exercise test was used to determine the repeatability of the following measurements in exercising horses: maximal oxygen consumption (VO2max), maximal heart rate (HRmax), velocity at a heart rate of 200 beats/min (V-200), oxygen consumption at a heart rate of 200 beats/min (VO2-200), oxygen consumption at HRmax (VO2-HRmax), work rate at a heart rate of 200 beats/min (W-200), work rate at HRmax (W-HRmax) and treadmill velocity at HRmax (V-HRmax). Six Standardbred geldings were exercised on three separate occasions on a treadmill set at an inclination of 6 degrees. ...
Sweeney RW, Beech J, Simmons RD, Soma LR.The pharmacokinetics of ticarcillin and clavulanic acid following administration by the intravenous (i.v.) and intramuscular (i.m.) routes were investigated in six normal adult horses. Following i.v. administration, the ticarcillin disposition data conformed to a two-compartment model with an elimination half-life of 1.0 h. The disposition of clavulanic acid was described by a one-compartment model with an elimination half-life of 0.40 h. Following i.m. administration, the half-lives of both drugs were prolonged (ticarcillin 1.8 h, clavulanic acid 1.2 h). The bioavailability of ticarcillin was...
Godovac-Zimmermann J, Conti A, James L, Napolitano L.The complete primary structure of donkey beta-lactoglobulin I was determined by pulsed-liquid phase microsequencing of tryptic peptides. The protein has been isolated in monomeric form and it corresponds to monomeric beta-lactoglobulin of type I. With the inclusion of donkey beta-lactoglobulin I there are 13% common residues amongst the members of the beta-lactoglobulin family. Donkey beta-lactoglobulin I is homologous to the retinol-binding protein, bilin-binding protein and five other proteins belonging to the new superfamily of hydrophobic molecule transporters. A rapid method for peptide i...
Weidolf LO, Lee ED, Henion JD.Sulfoconjugated anabolic steroids were separated by micro-bore high-performance liquid chromatography. The eluent was introduced into the atmospheric pressure ion source of the triple-quadrupole mass spectrometer via an ion spray liquid chromatograph/mass spectrometer interface operated in the negative ion mode. The limit of detection was 10 pg on-column by selected ion monitoring of the molecular ion and the response increased linearly over a concentration range of 2.4 orders of magnitude. Following work-up by a liquid-solid extraction procedure of equine urine samples, full-scan daughter ion...
Gleed RD, Dobson A.Observations were made on horses spontaneously breathing oxygen, with halothane at a constant end tidal concentration. The horses were positioned in dorsal recumbency for the first 45 minutes of each anaesthetic episode during which the arterial oxygen tension (PaO2) was found to peak and then decline. The remaining 60 minutes of each anaesthesia was used to test the effect of various manoeuvres on PaO2. The PaO2 of horses decreased further both when remaining in dorsal recumbency and when repositioned in right or left recumbency. In contrast, placing the horses in sternal recumbency for these...
Evans DL, Rose RJ.Cardiovascular and respiratory responses to submaximal exercise training were investigated in 6 thoroughbred racehorses. Oxygen uptake, heart rate (HR) and arteriovenous oxygen content difference were measured during incremental treadmill exercise tests, before and after 7 weeks of treadmill training. Cardiac output during exercise was calculated by the direct Fick technique. Maximal oxygen uptake (VO2max) was increased by 23% after training, from 129.7 ml/kg/min to 160.0 ml/kg/min. The treadmill speed at which VO2max was attained increased by 19%. The increased aerobic power after training wa...
Firth EC, Klein WR, Nouws JF, Wensing T.Single doses of sodium ampicillin (10 mg/kg) and kanamycin sulfate (5 mg/kg) were administered intramuscularly (i.m.) separately, and then together, to five pony mares. The plasma antibiotic concentration-time curves were constructed. The pharmacokinetic parameters of the antibiotics given separately were not altered by concurrent administration. Four of the five pony mares were then given the i.m. kanamycin/ampicillin combination 4 h after acute synovitis and fever had been induced by injection of lipopolysaccharide into the left intercarpal joint. The plasma concentration-time curves and the...
Stoianova LG, Abramova LA, Ladodo KS.The main biological parameters were studied in sublimated mare's milk: protein fraction composition, amino-acid spectrum, fatty-acid composition of lipids and the content of vitamins and mineral substances. A high biological value of the sublimated mare's milk has been proved, as well as significant proximity of its composition to human milk. Preliminary data have evidenced expediency of mare's milk use for the development of adapted milk mixtures for baby foods. However, the fatty component of the mixtures needs certain correction by addition of vegetable oil. The sublimated mare's milk can b...
Martens JG, Martens RJ, Renshaw HW.The capacity of hematogenous polymorphonuclear neutrophilic leukocytes (PMNL) to kill Rhodococcus equi was compared in horses of various ages. A radioisotope bactericidal assay was used to determine the capacity of PMNL to kill R equi. Assays were conducted on PMNL from horses in 3 groups: group I, 13 foals with a mean age of 3.3 days; group II, 10 group-I foals at a mean age of 35.7 days; and group III, adult dams of group-I foals. Bacteria were obtained from the lungs of a foal with R equi pneumonia and opsonized with fresh adult equine serum that contained R equi specific antibody. The mean...
Alexander SL, Irvine CH, Livesey JH, Donald RA.A non-surgical, non-stressful technique was used for collection of pituitary venous blood from five conscious horses every minute for two 10-min periods before and during isolation from the herd, which caused a predictable, yet humane and physiological, emotional stress. Pituitary blood was also sampled every 5 min for two approximately 90-min periods before and after isolation, while jugular blood was sampled every 15 min throughout the experiment. During isolation, all horses became agitated, hyperventilating and sweating. Packed red cell volume increased, as did pituitary venous concentrati...
Evans DL, Rose RJ.The effects of a respiratory gas collection mask on arterial blood gases, acid base values, oxygen content, respiratory frequency and heart rate, were investigated in standardbred horses during treadmill exercise at speeds up to 10 m sec-1 and a treadmill slope of 10 per cent. The mask had no significant effect on heart rates during exercise, but respiratory frequency was lower when the mask was used. The increase in respiratory frequency as treadmill velocity increased was also significantly slower with the mask operative. Arterial carbon dioxide tensions were significantly higher during exer...
Manohar M, Goetz TE, Holste LC, Nganwa D.Diaphragmatic O2 and lactate extraction were studied in 10 healthy ponies at rest and during treadmill exercise. The phrenic vein was aseptically catheterized via a lateral thoracotomy 8-35 days before the study. Arterial and phrenic venous blood samples were obtained simultaneously at rest and at 30-s intervals during 4 min of exertion. Three levels of exertion were studied (moderate, 10 mi/h; heavy, 15 mi/h; maximal, 20 mi/h), and a rest period of at least 90 min was allowed between them. Each pony was studied twice at least 2-3 days apart. At rest the diaphragmatic venous PO2, O2 saturation...
Clarke LL, Ganjam VK, Fichtenbaum B, Hatfield D, Garner HE.The effect of feeding frequency and associated meal size on the renin-angiotensin-aldosterone system (RAAS) in seven horses was examined. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen (MF), in which the ration was divided into six equal portions fed at 4-h intervals, or as a single large feeding (SF) given from 9 A.M. until 11 A.M. Plasma renin activity (PRA), aldosterone (PAC), cortisol (PCC), protein concentration (TP), packed cell volume (PCV), and serum sodium and potassium were measured serially. To prevent significant RAAS stimulation d...
Boyer RF, Clark HM, LaRoche AP.The reductive release of ferritin iron by several naturally occurring o-diphenols was studied. The initial rate of iron release was quantified by spectrophotometric measurement of the Fe(ferrozine)3(2+) complex, which absorbs maximally at 562 nm. The initial rate of iron release was dependent upon o-diphenol concentration, but not on the concentration of the chromophoric chelating agent, ferrozine, Stoichiometric measurements resulted in a ratio of 2Fe(II) released per molecule of o-diphenol. The series of o-diphenols studied included, caffeic acid, chlorogenic acid, dihydrocaffeic acid, 3,4-d...
Bijman J, Quinton PM.The effects of Ca2+, the cyclic nucleotides adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP), and other parameters of sweat secretion from single equine sweat glands were examined in vitro. Extracellular Ca2+, the Ca2+ ionophore A23187, and the Ca2+ channel antagonist verapamil were all without effect on sweat secretion. Prolonged rinsing of the glands in Ca2+-free Ringer solution with 5 mM ethylenediaminetetraacetic acid decreased the secretion to 30% of the control sweat rate in response to the beta-adrenergic agonist isoproterenol; the sweat respon...
Miller PA, Lawrence LM.Eight horses exercised to fatigue were used to characterize the resulting changes in blood pH, in blood lactate, free fatty acid, bicarbonate, and ammonia concentrations, and in muscle glycogen concentrations. The exercise test was conducted at a speed of 4.5 m/s on a motorized equine treadmill set at a 9% grade. At fatigue, all variables differed significantly (P less than 0.05) from base-line values. Heart rate averaged 191.1 +/- 6.5 beats/min at fatigue, and the plasma lactate concentrations increased from 7.8 +/- 0.95 mg/dl to 94.3 +/- 19.2 mg/dl. Ammonia concentrations increased from 66.7...
Reinert M, Calvete JJ, Sanz L, Töpfer-Petersen E.SSP-7 is a protein originally isolated from stallion seminal plasma. It has extensive amino acid sequence homology with boar spermadhesin AWN, and, like its porcine counterpart, SSP-7 displays zona pellucida-binding activity. Strikingly, however, immunohistochemical studies presented here show that the stallion and the boar spermadhesin homologues are secreted at different places of the male genital tract. Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover th...
Aurich C, Seeber P, Müller-Schlösser F.To maintain the fertility of stallion spermatozoa during cooled storage, extender media are added to semen. In this study, three semen extenders were compared: EquiPro which contains defined caseinates and whey proteins instead of dried skim milk. The extender is provided in dry form and dissolved in distilled water prior to use. EquiPro TM has the same composition as EquiPro but is provided in a sterilized ready-to-use liquid form. AndroMed-E contains soybean lecithin as protein source. Semen was collected from seven stallions. Ejaculates were divided into three aliquots, diluted with the dif...
diBella G, Scandariato G, Suriano O, Rizzo A.The dependence of blood oxygen affinity and the Bohr effect on the concentration of 2,3-diphosphoglycerate (DPG) in erythrocytes was investigated in 24 trotter horses and 24 healthy men. The oxygen tension at half saturation and standard conditions (P50st at pH 7.4, PCO2(40) mmHg and 37 degrees C) and the carbon dioxide or fixed-acid-induced Bohr effect (dlogP50/dpH) were determined. Samples of fresh blood and blood depleted of or enriched with DPG were studied. In the absence of measurable DPG, the equine and human blood had similar mean (SD) values of P50st (16.6 [0.6] and 16.2 [0.7] mmHg, r...
Sojka JE, Johnson MA, Bottoms GD.This study was conducted to investigate the effect of starting time on dexamethasone suppression test results in horses. Eight adult horses were used throughout the trial. Baseline cortisol levels were established by collecting cortisol levels twice daily, at 8:00 A.M. and 8:00 P.M. for 4 consecutive days. Morning baseline cortisol levels were 46.3 +/- 5.94 ng/ml, and evening baseline cortisol levels were 32.8 +/- 5.59 ng/ml. Although lower, the evening cortisol levels were not statistically different (P = 0.154) from the morning levels. Dexamethasone suppression tests initiated at either 9:00...
Segabinazzi LGTM, Landers M, Kent A, Peterson E, Gilbert R, French H.Due to the limited literature available evaluating doses of Prostaglandin F2α in donkeys, doses for horses have been extrapolated and used as guidelines. This study aimed to assess the efficacy and side effects of four different cloprostenol sodium and dinoprost tromethamine doses to induce luteolysis in jennies. Sixty-three cycles of seven Jennies (nine cycles per jenny) were used in this study. Seven days after ovulation, jennies randomly received one of the treatments in a crossover design as follows: Control, no treatment was administered; C1, 250 µg of cloprostenol sodium (CS, Estrumate...
Symons JE, Fyhrie DP, Hawkins DA, Upadhyaya SK, Stover SM.Race surfaces have been associated with the incidence of racehorse musculoskeletal injury, the leading cause of racehorse attrition. Optimal race surface mechanical behaviors that minimize injury risk are unknown. Computational models are an economical method to determine optimal mechanical behaviors. Previously developed equine musculoskeletal models utilized ground reaction floor models designed to simulate a stiff, smooth floor appropriate for a human gait laboratory. Our objective was to develop a computational race surface model (two force-displacement functions, one linear and one nonlin...
Ginther OJ, Beg MA.The temporal relationships between a pulse of 13,14-dihydro-15-keto-PGF(2alpha) (PGFM) and the concentrations of circulating hormones during the luteolytic period were studied for 11 pulses in 11 mares (Equus caballus) using samples collected hourly. Mean PGFM pulses encompassed 4h before to 4h after the peak, and hormone data were normalized to the PGFM peak (Hour 0). Concentration of progesterone decreased (P < 0.05) between Hours -4 and -3 and continued to decrease linearly throughout the PGFM pulse. The concentrations of cortisol and prolactin increased (P < 0.004) during Hours -4 to...
DelVento VR, Amann RP, Trotter GW, Veeramachaneni DN, Squires EL.A sample of testicular parenchymal tissue, approximately 2 x 7 x 7 mm, was aseptically removed from 1 testis in each of 9 stallions on day 0. Slight to moderate hemorrhage from the tunica albuginea was observed in 8 stallions, but bleeding from the parenchyma was detected in only 2 stallions. Stallions were castrated 27 days later. Normal development of granulation tissue was evident at the biopsy site, but hematomas were not observed. In situ measurement of the widths of the right and left testes, total scrotal width, and evaluation of testicular echogenicity during ultrasonography were varia...
Godovac-Zimmermann J, Shaw D, Conti A, McKenzie H.The presence of two new alpha-lactalbumins has been demonstrated in the colostrum of a single mare (Equus caballus, Persian Arab). They have been designated equine alpha-lactalbumin B and C, and that isolated previously from the milk of Australian horses (English Thoroughbred) as alpha-lactalbumin A. The primary structures of B/C have been determined by automatic Edman degradation of enzymatic cleavage of the oxidized protein. Cyanogen bromide cleavage of S-carbamoyl-methylated protein provided necessary overlapping peptides. Comparison of the sequences of B and C with that of A indicates 3 an...
Gasthuys F, De Moor A, Parmentier D.The effects of calcium chloride administered at low infusion rates on the cardiovascular depression and the blood calcium balance were studied during a constant halothane anaesthesia in dorsally recumbent ventilated ponies. A pronounced cardiopulmonary depression characterized by decreases of all cardiac parameters and lowering of the mean arterial blood pressure was observed after the initial anaesthetic stabilization period of 30 minutes in the ponies. A significant decrease in the total calcium plasma concentration together with a constant ionized and complexed calcium fraction was present ...
Stubley D, Campbell C, Dant C, Blackmore DJ, Pierce A.The concentration of copper and zinc in the blood and sera of over 300 Thoroughbreds in training was determined by atomic absorption between February 1979 and July 1981. The mean (+/- sd) concentration of copper in the serum of stabled Thoroughbreds (79 +/- 16 micrograms/dl) was significantly (P less than 0.0001) lower than that of those at grass (101 +/- 26 micrograms/dl), whereas the mean serum zinc concentration of stabled Thoroughbreds (170 +/- 54 micrograms/dl) was higher than that of those at grass (111 +/- 45 micrograms/dl). No such differences were observed in whole blood. There were m...
Donabedian M, Delguste C, Perona G, Lebecque P, Duboeuf F, Lepaga O, Martin-Rosset W.Bone mineral density (BMD) is correlated to mechanical properties of bone. In the horse, dual energy X-ray absorptiometry (DXA) has yet only been performed ex-vivo, but a new portable DXA device would be ideal for in-vivo BMD measurement. We explored field suitability, precision and accuracy of this device for in-vivo third metacarpal density assessment. Precision was analysed by calculating measurement variation under repeated measurement tests with (reproducibility) and without (repeatability) limb repositioning. Repeatability and reproducibility were tested ex-vivo, at the same time that in...
Flood PF, Marrable AW.The distribution of several hydroxysteroid dehydrogenases (HSD) was examined in a variety of equine placental and fetal tissues. The main points of interest were: (a) the lack of dehydrogenase activity in the gonad, (b) the appearance of a variety of HSDs in the trophoblast as early as 13 days of gestation, (c) the histochemical similarity between the cells of the trophoblast and the endometrial cup, and (d) the restriction of the strong endometrial 17beta-HSD reaction to those parts of the uterine epithelium directly apposed to the trophoblast.
Hernández-Avilés C, Castaneda C, Raudsepp T, Varner DD, Love CC.Acrosomal dysfunction has been considered as a cause of subfertility in males of different species, including stallions. A subset of subfertile stallions with acrosomal dysfunction is unique because they have normal sperm quality (motility, morphology, viability, and DNA quality). The current work aims to describe the clinical characteristics of subfertile stallions that were diagnosed with Impaired Acrosomal Exocytosis (IAE) by using two high throughput methods: flow cytometry and molecular genetic analysis, and to identify the prevalence of subfertility due to IAE in stallions evaluated at T...
Ansari Mood M, Rajaei SM, Faghihi H, Ghiadi A.This study was performed to evaluate the effect of topical 1% cyclopentolate hydrochloride on tear production (STT), intraocular pressure (IOP), and vertical pupil diameter (VPD) in healthy Turkman horses. Forty eyes of 20 clinically normal horses were used for this study, which were randomly assigned to two groups. Before instillation of 1% cyclopentolate, the baseline STT, IOP, and VPD of each group were recorded. Then, one drop of cyclopentolate was instilled randomly into one eye of each animal, and the contralateral eye served as control. Measurements were repeated at 20 minutes, 60 min...
Cymerys J, Słońska A, Chodkowski M, Golke A, Krzyżowska M, Bańbura MW.Equid herpesvirus 1 (EHV-1) causes respiratory disease, abortion and neurological disorders in horses. Similarly, to other alphaherpesviruses, EHV-1 is neurotropic and establishes latency in the neurons of its natural host. Despite the fact that many studies have been devoted to the pathogenesis of various clinical forms of EHV-1 infection, mechanisms of the neuronal damage are still not fully understood. The aim of this study was to define the phosphorylation status of tau protein in neuronal cell culture infected with EHV-1. Phosphorylation of tau was tested at tau-ser199/ser202, tau-ser404,...
Roberts CJ.Manual crushing of one blastocyst performed on 181 bicornuate twin pregnancies between Days 24 and 45 has shown that the uncrushed blastocyst can either survive and develop normally to full term or may be rejected and resorbed like its crushed twin, depending mainly on the stage of pregnancy. Crushing, which causes rupture of fetal membranes, results in a rapid fall in the survival rate of the uncrushed blastocyst when performed after Day 31. In some mares rupture is not possible after Day 35 even if extreme pressure is used. Crushed, but unruptured, blastocysts mainly between Days 35 and 45 m...
Mykkänen AK, Niku M, Ilves M, Koho NM.To characterize the expression of monocarboxylate transporters (MCTs) 1 and 4 and the ancillary protein CD147 in the intestinal tract of healthy equids and determine the cellular location of CD147 in the intestinal epithelium. Methods: 12 healthy horses and ponies slaughtered for meat production or euthanized for reasons unrelated to gastrointestinal tract disease. Methods: The entire gastrointestinal tract was removed from each equid within 45 minutes after slaughter or euthanasia. Tissue samples were obtained from the antimesenteric side of the duodenum, jejunum, ileum, middle part of the ce...
Stefanetti V, Pascucci L, Wilsher S, Cappelli K, Capomaccio S, Reale L, Passamonti F, Coletti M, Crociati M, Monaci M, Marenzoni ML.Endogenous retroviruses (ERVs) are proviral phases of exogenous retroviruses, which have coevolved with vertebrate genomes for millions of years. The conservation of ERV genes throughout evolution suggests their beneficial effects on their hosts' survival. An example of such positive selection is demonstrated by the syncytin gene, which encodes a protein with affinity for various mammalian placentas that is involved in the formation of syncytiotrophoblasts. Although the horse has an epitheliochorial placenta, in which the fetal trophoblasts are simply apposed to the intact uterine epithelium, ...
Youngblood CD, Hodgson DS, Beard WL, Song Y, Prakash P, Heflin LV.Recumbency affects respiratory mechanics and oxygenation in anesthetized horses. Changes in pleural and abdominal pressures that can impair ventilation have not been described in all recumbencies. The objective of this study was to determine the effects of patient positioning on transdiaphragmatic pressure and selected hemodynamic variables. Horses were maintained under total intravenous general anesthesia with nasal oxygen supplementation. Transnasal balloon catheters in the stomach and thoracic esophagus were used to measure intrathoracic and gastric pressures in standing horses and in anest...
Tzelos T, Blissitt KJ, Clutton RE.To determine whether preoperative electrocardiographic measurements linked to sympathetic nervous activity could be used to predict recovery quality after general anaesthesia in horses. Methods: Prospective, clinical study. Methods: Eighteen adult client-owned horses. Methods: The electrocardiogram (ECG) was recorded presurgery in horses under three standard conditions: stabled unattended; with a groom whilst being led along a standard course; alone in the induction box. After surgery, each animal's recovery quality was scored by eight experienced anaesthetists or technicians using Donaldson's...
Nicodemus MC, Holt KM, Swartz K.The running walk of the Tennessee Walking Horse is often described as a faster variation of the walk, indicating the importance of velocity on the mechanics of the gait. Variations in gait variables create difficulties in clearly identifying the normal and abnormal running walk in a clinical evaluation. The objectives of this study were, therefore, to describe the flat shod running walk and to determine the relationship between velocity and the running walk. From frame-by-frame analysis of 60 Hz film, temporal variables were averaged for 6 strides from 6 horses performing an 'easy' (slow) and ...
Gérard C, Valenchon M, Poulin N, Petit O.In collective movements, some individuals are more effective and attractive leaders than others. Parameters such as social network, personality, and physiologic needs failed to explain why group members follow one leader more than another. In this study in the domestic horse, we propose to focus on the leader's attitude and its impact to the followers' recruitment during two conditions: spontaneous group departures or experimentally induced departures. We postulate that the expressiveness of the leader could enhance its attractiveness and thus produce a successful followership. We found that a...
Irvine CH, Alexander SL, Turner JE.The possibility of seasonal variation in the feedback effect of testosterone or oestradiol was investigated by giving replacement treatment to geldings for 2-3 weeks during breeding and non-breeding seasons. In the non-breeding season, testosterone suppressed LH values (mean +/- s.e.m., ng/ml) in all geldings (before treatment, 7.5 +/- 2.3; final treatment week, 1.8 +/- 0.2; P less than 0.05), whereas early in the breeding season, testosterone caused a prolonged rise in LH (before, 6.8 +/- 2.3; final week, 18.9 +/- 6.4; P less than 0.05). In all testosterone experiments, LH returned to pretrea...
Moens Y, Lagerweij E, Gootjes P, Poortman J.Effects of differential ventilation on gas exchange were studied in 7 isoflurane-anesthetized, laterally recumbent horses, and were compared with effects of conventional ventilation, using similar minute volume. A tracheal tube-in-tube intubation technique allowed each lung to be connected separately to an anesthetic circle system with a ventilator. Two distribution patterns of tidal volume were investigated; half the tidal volume was distributed to each lung and two-thirds the tidal volume was distributed to the dependent lung. Effects of the combination of these patterns with positive end-ex...
Jagodzinski PW, Funk GF, Peticolas WL.The nature of the binding of aromatic aldehyde and aromatic alcohol substrates to the catalytic zinc of equine liver alcohol dehydrogenase has been studied by using resonance-enhanced Raman spectroscopy. When an excess of both enzyme and coenzyme to substrate is used, a stable ternary chemical intermediate is formed between liver alcohol dehydrogenase and the reduced coenzyme, nicotinamide adenine dinucleotide, and the aldehyde, p-(dimethylamino)benzaldehyde, in the pH range 8.5-0.6. Resonance-enhanced Raman spectra clearly show that this same intermediate is formed between the excess enzyme, ...
Zekas LJ, Ramirez S, Brown MP.Left dorsal displacement of the large colon was diagnosed in a 3-year-old Thoroughbred gelding. Conservative treatment that included lunging after administration of phenylephrine and rolling while under general anesthesia was not successful. The displaced segment of colon was reduced surgically through a ventral midline incision, but displacement recurred 4 days after surgery. Ablation of the nephrosplenic space by suturing the nephrosplenic ligament to the splenic capsule was performed through the left flank. At followup 1 year after surgery, the horse had not had further signs of colic and h...
Topper MJ, Prasse KW, Morris MJ, Duncan A, Crowe NA.To adapt and characterize a human ELISA kit to quantify thrombin-antithrombin III (TAT) complexes in horses, and to evaluate TAT as a marker for hypercoagulation in horses. Methods: 29 clinically normal horses used as controls, and 4 ill horses used to evaluate assay for known causes of hypercoagulation. Methods: A commercially available human sandwich-type ELISA kit with 2 antibodies against human thrombin and antithrombin III that bind selectively to their corresponding TAT antigenic sites was used. Equine TAT standards were made from purified equine thrombin and antithrombin III. Proteins d...
