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.
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...
Muccioli G, Bellussi G, Ghé C, Pagnini G, Di Carlo R.The binding of 125I-labeled ovine prolactin (125I-oPRL) to membranes from different brain regions of pigeon, rabbit, rat, pig, calf, horse, and ewe was studied. The hypothalamus from rabbit, pig, horse, and pigeon showed a low but specific binding for 125I-oPRL clearly different from the other brain regions examined (cortex and cerebellum), whereas in the brain from rat, calf, and ewe the binding was very small and quite uniform in the various regions. Also the membranes from choroid plexus of rabbit, pig, calf, and horse showed an evident specific binding for prolactin. The binding of 125I-oP...
Anderson GB.Investigations on the mechanisms that allow survival of the fetal allograft have been extended by pregnancies in which the fetus and pregnant female are from different species. Such interspecific pregnancies are useful models for the study of maternal/fetal interactions and also may assist in the preservation of endangered species. Results of experiments with three different interspecific model systems are discussed: a murine model using Mus musculus and M. caroli; an equine model involving primarily the domestic horse and donkey, but including several wild Equidae; and a bovid model that cros...
Garza F, Thompson DL, Mitchell PS, Wiest JJ.Five lighthorse mares were actively immunized against gonadotropin releasing hormone (GnRH) conjugated to bovine serum albumin (BSA) to study the involvement of GnRH in luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion following ovariectomy (OVX) and after administration of testosterone propionate (TP). Five mares immunized against BSA served as controls. Immunizations were started on November 1, and OVX was performed in June (d 1). All mares were treated with TP from d 50 to 59 after OVX. On the day of OVX, concentrations of LH were lower (P less than .05) in GnRH-immu...
Freeman DW, Potter GD, Schelling GT, Kreider JL.Nitrogen metabolism was measured in five mature geldings performing varying levels of work that simulated race training. Following an initial maintenance period without forced exercise, workload was increased in succeeding 18-d periods by doubling the distance the horses were galloped in each period from period 2 through 4. A 4-d N balance experiment was conducted at the end of each 18-d period. The maximum distance galloped daily, which was in period 4, was repeated in period 5. Then, workloads were decreased through period 7. Nitrogen balance was determined in two additional periods, 8 and 9...
Songer JG, Beckenbach K, Marshall MM, Olson GB, Kelley L.Isolates (n = 94) of Corynebacterium pseudotuberculosis were obtained from sheep, goats, horses, and cattle from various parts of the world. The isolates were characterized biochemically and by restriction endonuclease analysis of DNA. We found near homogeneity in the ability of isolates to ferment carbohydrates and to produce urease. All isolates produced phospholipase D and catalase. The ability of isolates from horses to reduce nitrate, the inability of isolates from sheep and goats to do so, and the correlation of this characteristic with results of restriction endonuclease analyses confir...
Koblik PD, Hornof WJ, Seeherman HJ.Review of 121 bone scintigrams obtained on racing Thoroughbred horses with clinical histories indicative of forelimb lameness revealed 3 scintigraphic patterns of stress-induced trauma to the dorsal cortex of the third metacarpal bone: (1) focal, intense uptake associated with recent stress fracture; (2) regional uptake of varying intensity or a mixed pattern of uptake associated with chronic stress fracture; and (3) diffuse, mild to moderate uptake associated with periostitis (bucked shins). The latter scintigraphic pattern appeared to be an exaggerated manifestation of the normal remodeling ...
Rose RJ, Hodgson DR, Kelso TB, McCutcheon LJ, Reid TA, Bayly WM, Gollnick PD.This study determined maximal O2 uptake (VO2max), maximal O2 deficit, and O2 debt in the Thoroughbred racehorse exercising on an inclined treadmill. In eight horses the O2 uptake (VO2) vs. speed relationship was linear until 10 m/s and VO2max values ranged from 131 to 153 ml.kg-1.min-1. Six of these horses then exercised at 120% of their VO2max until exhaustion. VO2, CO2 production (VCO2), and plasma lactate (La) were measured before and during exercise and through 60 min of recovery. Muscle biopsies were collected before and at 0.25, 0.5, 1, 1.5, 2, 5, 10, 15, 20, 40, and 60 min after exercis...
Wyatt CR, Davis WC, McGuire TC, Perryman LE.Six monoclonal antibodies reacting with equine T lymphocytes at different stages of maturation were selected from antibodies produced against lymphoid cell preparations. EqT12 and EqT13 antibodies identified subsets of cortical thymocytes with high terminal deoxynucleotidyltransferase (TdT) activity and no phytolectin responsiveness. EqT12+ thymocytes were scattered throughout the cortex while EqT13+ thymocytes were located in the subcapsular cortex. EqT12 bound to small numbers of bone marrow cells, splenocytes, and circulating lymphoid cells, but not to mature T lymphocytes. EqT13 bound to v...
Oftedal OT, Jenness R.Milk samples of four species of wild equids (onager, Equus hemionus onager; mountain zebra, E. zebra hartmannae; plains zebra, E. burchelli; Przewalski horse, E. caballus przewalskii) and two domesticated equids (ass, E. asinus; pony, E. caballus) were analysed. At mid to late lactation the milks of all species were very similar, containing on average 10-12% total solids, 1-2% fat, 1.6-1.8% true protein, 6-7% 'lactose', 0.3-0.5% ash, 0.08-0.12% calcium, 0.04-0.07% phosphorus and a calculated energy content of 2.0-2.4 kJ/g. Milk samples collected in the first 2 weeks after birth showed elevated...
Gibbs PG, Potter GD, Schelling GT, Kreider JL, Boyd CL.Mature ponies fitted with permanent ileal cannulas were used in a 3 X 3 Latin square experiment to quantify prececal, postileal and total tract digestion of hay protein. Coastal Bermuda grass (CB), containing 11.7% crude protein, and two qualities of alfalfa, containing 15.0% (low-protein alfalfa; LA) and 18.1% (high-protein alfalfa; HA) crude protein, were fed in coarsely chopped form at 2% of body weight daily. Total tract apparent digestibility of the N in HA (73.8%) was higher than that in CB (57.0%; P less than .05) and was slightly higher than that in LA (66.1%; P less than .10). Nitroge...
Stull CL, Rodiek AV.Two experiments were conducted to determine the response of blood glucose, insulin and cortisol levels to four common equine diets. Experiment 1 was designed to determine the diurnal variation of glucose and two glucoregulatory hormones, insulin and cortisol, in four fasting geldings. No diurnal variation was observed in either glucose or insulin levels during the 24-h sampling period. However, cortisol levels did exhibit a circadian rhythm, with elevated values observed in the morning and low values in the evening. Experiment 2 investigated the response of glucose, insulin, cortisol and selec...
Kasman LH, Hughes JP, Stabenfeldt GH, Starr MD, Lasley BL.Serum and urinary estrone sulfate concentrations were determined in 7 pregnant mares before and after prostaglandin-induced abortion (n = 4) or surgical removal of the fetus (n = 3) to determine the source of estrogen during early pregnancy (gestation days [GD] 44 to 89). Estrone sulfate concentrations also were determined in serum samples (stored frozen for 2 years) from 3 mares that had been ovariectomized between GD 51 and 58. Estrone sulfate concentrations decreased in serum and urine after expulsion or removal of the fetus (urinary patterns were more definitive than were patterns for seru...
Gronwall R, Brown MP.Para-aminohippuric acid (PAHA, 0.1 mg/min/kg of body weight) was infused IV into 2 mares, followed by concurrent IV infusion of PAHA and probenecid (0.075, 0.15, 0.25, or 0.35 mg of probenecid/min/kg). Probenecid infusion reduced the clearance of PAHA at serum probenecid concentrations greater than 55 micrograms/ml. At 12-hour intervals, probenecid (in 5 repeated doses - 50, 75, 100, or 200 mg/kg) was administered by gavage to 2 mares. Mean serum probenecid concentration was greater than 55 micrograms/ml for all dosages. At dosages less than 200 mg/kg, accumulation of probenecid in the serum w...
Young JD, Mason DK, Fincham DA.Na+-dependent system ASC and Na+-independent system asc are characterized by a common selectivity for neutral amino acids of intermediate size such as L-alanine and by their interactions with dibasic amino acids. For system ASC, the positive charge on the dibasic amino acid side chain is considered to occupy the Na+-binding site on the transporter. We report here the use of harmaline (a Na+-site inhibitor in some systems) as a probe of possible structural homology between these two classes of amino acid transporter. Harmaline was found to inhibit human erythrocyte system ASC noncompetitively w...
Erickson HH, Sexton WL, Erickson BK, Coffman JR.The recognition of the horse as a natural athlete has led to increased interest in equine sports medicine, exercise physiology, new training methods, and factors improving the performance of horses (Engelhardt, 1977; Milne et al., 1977; Bayly et al., 1983b; Persson et al., 1983). A considerable amount of research has been performed in recent years in order to describe the physiological responses of the horse to exercise and training (for reviews see Engelhardt, 1977; Physick-Sheard, 1985; Rose, 1985). Most of these studies, however, have examined the effects of acute exercise training rather t...
Olson LE, Lai-Fook SJ.Pleural liquid pressure was measured at end expiration in 11 spontaneously breathing anesthetized ponies in the prone and supine positions. A liquid-filled capsule was implanted into a rib to measure pleural liquid pressure with minimal distortion of the pleural space (Wiener-Kronish et al., J. Appl. Physiol. 59: 597-602, 1985). Capsule position relative to lung height was measured from thoracic radiographs taken in each position. In each body position, pleural liquid pressure was most negative in the superior lung regions and least negative in the inferior lung regions. In the supine position...
Serteyn D, Deby-Dupont G, Pincemail J, Mottart E, Philippart C, Lamy M.Arachidonic acid cyclooxygenase metabolites, thromboxane B2 (TXB2), prostaglandin E2 (PGE2) and 6-keto-prostaglandin F1 (6-keto-PGF1) were measured in horses where anaesthesia was maintained with halothane. Two horses suffering from postanaesthetic myositis were compared with four normal horses. TXB2 and PGE2 levels were higher in mixed venous blood drawn from the myopathic horses. An increase of TXB2 and PGE2 levels appeared when myopathic horses were rolled into dorsal recumbency after a prolonged period of lateral recumbency. One hour after the end of anaesthesia, TXB2 had continued to incr...
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...
Garg M, Sharma D, Kumar R.1-allyl-3-methylimidazolium chloride (AMIMCl) acts as a potential green solvent for proteins. The present work provides a possible pathway by which the structural, kinetic, thermodynamic, and folding properties of horse cytochrome c (cyt c) are affected in green aqueous-AMIMCl systems. Analysis of the effect of AMIMCl on thermodynamic stability, refolding/unfolding kinetics, and motional dynamics of cyt c provided important information, (i) AMIMCl decreases the thermodynamic stability of reduced cyt c and also strengthens the guanidinium chloride (GdmCl)-mediated decrease in thermodynamic stab...
Boss MA, Chris Hammel P.The influence of proton diffusion on nuclear magnetic resonance (NMR) relaxation was investigated in the presence of horse spleen ferritin at 7 T. Binary mixtures of water and glycerol were used to control diffusion within the range of 0.6-2.0 × 10(-9)m(2)/s, which was confirmed by pulsed gradient techniques. The effect of chemical exchange by hydrolysis between water and glycerol on relaxation was characterized with Carr-Purcell-Meiboom-Gill (CPMG) dispersion experiments. The relaxation rate enhancement of the protons due to ferritin was found to be inversely proportional to the diffusion co...
Mair TS, Stokes CR, Bourne FJ.An indirect immunoperoxidase technique was used to demonstrate both free immunoglobulin and immunoglobulin-containing plasma cells of IgG, IgA, and IgM classes in the mucosa of the equine respiratory tract. IgA-producing plasma cells predominated in the upper airways, whereas IgG-producing cells predominated in the lower respiratory tract. IgM-secreting cells were uncommon, but present in their highest numbers in the nasopharynx. Plasma cells specific for all of the immunoglobulin classes were identified in the surface epithelium, lamina propria connective tissue, glandular tissue and organise...
Hyde KA, Aguiar FLN, Alves BG, Alves KA, Gastal GDA, Gastal MO, Gastal EL.Characterization of the ovarian preantral follicle population is a necessary step to improve understanding of folliculogenesis and ovarian physiology. Therefore, in the present study, the preantral follicle population in the equine ovary in young and old mares was investigated according to follicular morphology, follicular class, distance from the geometric center using ovarian maps, and follicular density within ovarian portions (lateral vs intermediary) and regions (dorsal vs ventral). Ovaries were collected from an abattoir and histologically processed for evaluation, and the follicle popul...
Aramaki S, Suzuki E, Ishidaka O, Momose A.The effects of exercise on the metabolism of caffeine (CA) were studied 3h after administration of the drug to race horses which then underwent exercise sets (1000-m gallop). Analysis was made of pharmacokinetics of CA, changes in its plasma concentrations, its metabolites, i.e., theophylline (TP), theobromine (TB) and paraxanthine (PX), and the molar concentration ratios of CA to these metabolites. After exercise, AUC and t1/2 tended to decrease, and the concentration of CA decreased, while the concentrations of TP and TB significantly increased. The TP/CA ratio and TB/CA ratio significantly ...
Foster AP, Cunningham FM.Equine eosinophils and neutrophils are believed to play an important part in the protection of horses against parasitic and bacterial invasion. Eosinophils may also play a key role in the pathogenesis of equine inflammatory conditions such as the allergic skin disease, insect hypersensitivity. The factors which stimulate the respiratory burst of equine eosinophils and neutrophils are poorly understood. The first aim of the present study was to determine the effects of the phorbol ester, phorbol myristate acetate (PMA), which is believed to activate intracellular protein kinase C, and opsonised...
Silberzahn P, Rashed F, Zwain I, Leymarie P.An homogenate from cortical tissue of mare adrenals was incubated in the presence of tritiated pregnenolone. The (3H) androstenedione and the (3H) testosterone synthesized during the incubation were extracted, purified, and co-crystallized to constant specific activity in the presence of unlabeled carriers. The rate of conversion of pregnenolone to androstenedione and testosterone was of the order of 5 and 0.15 per cent respectively. The high ratio of (3H) androstenedione to (3H) testosterone observed in this study suggests that androstenedione is the main androgen produced by mare adrenals. I...
Allen MJ, Jemmerson R, Nall BT.Refolding of surface epitopes on horse cytochrome c has been measured by monoclonal antibody binding. Two antibodies were used to probe re-formation of native-like surface structure: one antibody (2B5) binds to native cytochrome c near a type II turn (residue 44) while the other (5F8) binds to a different epitope on the opposite face of the protein near the amino terminus of an alpha-helical segment (residue 60). The results show that within the first approximately 100 ms of refolding all of the unfolded protein collapses to native-like folding intermediates that contain both antibody binding ...
van Bergen T, Doom M, van den Broeck W, Wiemer P, Clegg PD, Cornillie P, Martens A.There are no previous studies correlating the anatomy of the equine epiploic foramen and its defining structures with laparoscopic images. Objective: The purpose of this study was to describe the precise anatomy of the epiploic foramen and omental vestibule, to quantify the dimensions of the epiploic foramen and to relate these findings to laparoscopic images. Methods: Descriptive study of cadaver material and laparoscopic images. Methods: Thirty-two horses subjected to euthanasia for reasons unrelated to colic were studied. Two cadavers were used to make vascular casts of the coeliac artery a...
Supokawej A, Korchunjit W, Wongtawan T.The Wingless and Int-1 (WNT) and bone morphogenic protein/growth differentiation factor (BMP/GDF) signalling pathways contribute significantly to the development of the musculoskeletal system. The mechanism by which they contribute is as follows: BMP/GDF signalling usually promotes tendon differentiation, whereas WNT signalling inhibits it. We hypothesised that inhibiting WNT and subsequently stimulating BMP signalling may enhance the tenogenic differentiation of stem cells. The objective of this study was to determine whether a combination of WNT inhibitor (KY02111) and BMP12/GDF7 protein cou...
Casanova E, Knowles TDJ, Outram AK, Stear NA, Roffet-Salque M, Zaibert V, Logvin A, Shevnina I, Evershed RP.Direct and accurate radiocarbon dating of lipid residues preserved in ceramics is a recently established method that allows direct dating of specific food products and their inception in human subsistence strategies. The method targets individual fatty acids originating from animal fats such as ruminant dairy, ruminant adipose, non-ruminant adipose and aquatic fats. Horse lipid residues found in Central Asian pottery vessels are also directly dateable using this new method. Here we present the identification of equine lipid residues preserved in two pottery assemblages from the Neolithic and E...
Sandbaumhüter FA, Gittel C, Larenza-Menzies MP, Theurillat R, Thormann W, Braun C.The enantioselectivity of the pharmacokinetics of methadone was investigated in anesthetized Shetland ponies after a single intravenous (0.5 mg/kg methadone hydrochloride; n = 6) or constant rate infusion (0.25 mg/kg bolus followed by 0.25 mg/kg/h methadone hydrochloride; n = 3) administration of racemic methadone. Plasma concentrations of l-methadone and d-methadone and their major metabolites, l- and d-2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), respectively, were analyzed by CE with highly sulfated γ-cyclodextrin as chiral selector and electrokinetic analyte injection from...
de Haas GH, Dijkman R, Lugtigheid RB, Dekker N, Van den Berg L, Egmond MR, Verheij HM.The inhibitory power (Z) of a number of (R)-1-alkyl-2-acylamino phospholipid analogues was determined for three mammalian phospholipases A2 from pig, ox and horse pancreas. All three enzymes display a clear preference for anionic (phosphoglycol) inhibitors over the zwitterionic (phosphocholine) derivatives; this effect is most pronounced for the bovine enzyme. Upon variation of the 1-alkyl chain length, the bovine and equine phospholipases, like the porcine enzyme in previous studies, show an optimum in Z for a six-carbon alkyl group. The introduction of a double bond in the 2-acylamino group ...
Fujiwara K, Ikeguchi M, Sugai S.The urea-induced unfolding transition of equine beta-lactoglobulin was studied at pH 8.7 using circular dichroism (CD), ultracentrifugation, and gel filtration chromatography. The unfolding transition curves showed that at least one intermediate accumulates at moderate concentrations of urea. Furthermore, analytical ultracentrifugation experiments indicated that the intermediate forms a dimer. Thus, the urea-induced unfolding transition was measured by CD at various protein concentrations and was analyzed by a model assuming the four conformational states (the native, intermediate, dimeric int...
Peters LW, Smiet E, de Sain-van der Velden MG, van der Kolk JH.Acylcarnitines play an important role in fuel metabolism in skeletal muscle. Objective: To assess acylcarnitine ester utilization by the hindlimb of horses at rest and following low intensity exercise and carnitine supplementation. Methods: Acylcarnitine ester uptake by the hindlimb was investigated using the arteriovenous difference technique. Blood from six warmblood mares (mean age 12 ± 3 (SD) years and weighing 538 ± 39 kg) was collected simultaneously from the transverse facial artery and from the caudal vena cava. Food was withheld for 12 hours prior to exercise. Exercise comprised a s...
Wells HC, Sizeland KH, Kirby N, Haverkamp RG.Thin, strong scaffold materials are needed for surgical applications. New materials are required, particularly those readily available, such as from non-human sources. Bovine amniotic membrane (antepartum) and equine amniotic membrane (postpartum) were characterized with tear and tensile tests. The structural arrangement of the collagen fibrils was determined by small-angle X-ray scattering, scanning electron microscopy, and ultrasonic imaging. Bovine amnion had a thickness-normalized tear strength of 12.6 (3.8) N/mm, while equine amnion was 14.8 (5.3) N/mm. SAXS analysis of the collagen fibri...
Fielding CL, Stolba DN.Changes in arterial pressure due to respiratory phases have been used to predict fluid responsiveness in a number of species and pulse pressure variation (PPV) and systolic pressure variation (SPV) are commonly used. The relationship between PPV and SPV has not been described in horses. Objective: To describe and compare PPV and SPV values of horses under general anesthesia. Methods: Twenty-six horses undergoing general anesthesia and receiving mechanical ventilation were enrolled in the study. Recordings of maximal and minimal values of pulse pressure and systolic pressure were calculated eve...
Schauvliege S, Van den Eede A, Duchateau L, Pille F, Vlaminck L, Gasthuys F.To compare cardiac output () measurements using lithium dilution (LiDCO) and pulse contour analysis (PulseCO) techniques in isoflurane-anaesthetized ponies before and during the administration of different inotropic/vasoactive drugs. Methods: Prospective randomized experimental cross-over trial. Methods: Six ponies aged 5.0 +/- 1.6 (4-6.5) years and weighing 286 +/- 53 (212-368) kg. Methods: After sedation (romifidine) and induction (midazolam + ketamine), anaesthesia was maintained with isoflurane in oxygen. After 90 minutes (= T0), one of four treatments was administered: saline 0.1 mL kg(-1...
Merlo B, Mari G, Iacono E.The increase in demand for in vitro produced horse embryos is fostering the development of commercial laboratories for this purpose. Nevertheless, blastocyst production after intracytoplasmic sperm injection (ICSI) is still not as great as desired in most of these laboratories. In relation to horse oocyte classification, both expanded and compact cumulus-oocyte-complexes (COCs) are used for in vitro embryo production. The aim of this study was to compare in vitro embryo developmental capacity of COCs from horses including those with only the corona radiata, frequently collected after aspiratio...
Heidbuchel A, Van Rossom S, Molenaers N, Minguet P, Jonkers I.In dressage riding, rider posture plays an important role in the performance of the exercises. The purpose of this study was to compare physical fitness and posture on an equestrian simulator between different competitive dressage rider skill levels. Participants (ten expert and twelve novice competitive dressage riders) performed a physiotherapeutic screening test and an equestrian simulator test. The expert rider group (G2) had less variability in both left (P = .002) and right (P = .021) rein force during medium canter on the simulator compared to the novice rider group (G1). The should...
Jose-Cunilleras E, Hinchcliff KW, Lacombe VA, Sams RA, Kohn CW, Taylor LE, Devor ST.Fatiguing exercise substantially decreases muscle glycogen concentration in horses, impairing athletic performance in subsequent exercise bouts. Our objective was to determine the effect of ingestion of starch-rich meals after exercise on whole body glucose kinetics and muscle glycogen replenishment. In a randomized, cross-over study seven horses with exercise-induced muscle glycogen depletion were either not fed for 8 h, fed half of the daily energy requirements ( approximately 15 Mcal DE) as hay, or fed an isocaloric amount of corn 15 min and 4 h after exercise. Starch-rich meals fed after e...
Gomez-Cuetara C, Flores JM, Sanchez J, Rodriguez A, Sanchez MA.An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reac...
Oberhaus EL, Thompson DL, Foster BA, Pinto CR.This experiment assessed the hormonal production, secretory aspects, and changes in luteinizing hormone (LH) receptor gene expression of early induced ovulatory-sized follicles relative to the first ovulatory-sized follicles occurring naturally in the spring. Anovulatory mares were treated on January 21 with (1) 50 mg of estradiol cypionate (ECP, n = 8) alone or (2) with ECP followed by two 3-g sulpiride injections (n = 8), 5 and 12 days later. Half of each group also received complete follicle ablation via transvaginal aspiration before ECP treatment. Ovaries were scanned regularly until ...
Gahne S, Gånheim A, Malmgren L.Different insemination doses have been used for artificial insemination(AI) in horses. Since the insemination dose can affect the pregnancy rate, it is important to ensure that an adequate dose be used regardless of the type of inseminationprotocol used. The aim of this study was to find out if it is possible to decrease the insemination dose from 500 x 10(6) progressively motile spermatozoa to 300 x 10(6) progressively motile spermatozoa and still maintain an acceptable pregnancy rate when using extended fresh semen. Thirteen stallions of known fertility and a well-defined group of 64 mares w...
Cavens VJ, Gemensky-Metzler AJ, Wilkie DA, Weisbrode SE, Lehman AM.To describe the long-term histologic and intraocular pressure (IOP) lowering effects of diode laser transscleral cyclophotocoagulation (TSCP) on the normal equine eye. Methods: Eight normal adult horses. Methods: TSCP was performed in one randomly assigned eye. Sixty spots were treated at settings of 1500 ms and 1500 mW. Two horses were randomly selected for euthanasia at 2, 4, 12, or 24 weeks post-TSCP. Both eyes were enucleated and histologically evaluated. Intraocular pressure was measured by applanation tonometry prior to TSCP, immediately post-TSCP, twice daily for 7 days post-TSCP and th...
Zacharias JR, Lescun TB, Moore GE, Van Sickle DC.To determine the effect of 2 hydroxyapatite pin coatings on heat generated at the bone-pin interface and torque required for insertion of transfixation pins into cadaveric equine third metacarpal bone. Methods: Third metacarpal bone pairs from 27 cadavers of adult horses. Methods: Peak temperature of the bone at the cis-cortex and the hardware and pin at the trans-cortex was measured during insertion of a plasma-sprayed hydroxyapatite (PSHA)-coated, biomimetic hydroxyapatite (BMHA)-coated, or uncoated large animal transfixation pin. End-insertional torque was measured for each pin. The bone-pi...
Hodge SL, Kreider JL, Potter GD, Harms PG, Fleeger JL.Over a 2-year period, mares (n = 32) of predominantly Quarter Horse breeding and their foals were used to study the effects of photoperiod on reproduction during the periparturient period. Specific objectives of the study were (i) to evaluate the effects of an extended photoperiod regimen (16 hours' light) on gestation length, foal development, and postpartum reproductive performance, and (ii) to measure changes in plasma progesterone concentrations during the last trimester of gestation and plasma luteinizing hormone (LH) concentrations after foaling until ovulation. Mares in the extended day...
