The pH level in horses is a measure of the acidity or alkalinity of various bodily fluids and tissues, which can influence numerous physiological processes. In horses, pH balance is essential for maintaining metabolic functions and overall health. The pH of blood, for example, is maintained within a narrow range through various buffering systems to ensure optimal cellular activity and enzyme function. Deviations from the normal pH range can indicate underlying health issues, such as metabolic disorders or respiratory problems. This topic encompasses peer-reviewed research studies and scholarly articles that explore the regulation, measurement, and implications of pH levels in equine biology, including their impact on performance, digestion, and disease states.
Carregaro AB, Mataqueiro MI, Soares OA, Queiroz-Neto A.The study of caffeine in racing horses has been of growing concern in veterinary sports medicine since the Association of Racing Commissioners International (ARCI) stated that it has no valid therapeutic use in racehorses. We examined the kinetic alterations in the urinary excretion and salivary secretion of caffeine in seven horses subjected to urinary acidification using ascorbic acid because this procedure can simulate the acidosis that follows anaerobic exercise. They participated in two treatment groups: the control group (SG) received 500 ml of saline and then 2.0 mg kg(-1) caffeine i.v....
Deane JC, Dagleish MP, Benamou AE, Wolf BT, Marlin D.To evaluate the consistency of partial pressures (P) of arterial oxygen (aO(2)), arterial carbon dioxide (aCO(2)) and pH measurements in equine carotid arterial blood samples taken into syringes made from three different materials and stored at room temperature or placed in iced water for measurement at three different times. Methods: Prospective observational study over 19 days. Methods: Four clinically normal Thoroughbred or Thoroughbred-cross horses (three geldings, one mare, mean age 6.25 years, range 5-7 years). Methods: Identical blood samples were taken on two separate occasions from th...
Mudge MC, Macdonald MH, Owens SD, Tablin F.To compare viability of equine whole blood stored by 4 different methods, and to establish optimal storage protocols for an equine autologous blood donation program. Methods: In vitro study of stored equine whole blood. Animals- Six healthy adult horses. Methods: Blood from each horse was collected into 4 different containers: glass bottles containing acid-citrate-dextrose solution (ACD), plastic bags containing ACD, citrate-phosphate-dextrose (CPD), and CPD with supplemental adenine (CPDA-1). Blood was stored for 5 weeks and sampled at 2-day intervals. Standard hematologic and biochemical var...
Sanchez LC, Murray MJ, Merritt AM.To evaluate the efficacy of omeprazole paste, a commonly used antiulcer drug, on intragastric pH in clinically normal neonatal foals. Methods: 6 clinically normal foals between 5 and 14 days of age. Methods: Intragastric pH was recorded in each foal by use of a disposable antimony pH electrode with internal reference. Values for intragastric pH were recorded every 4 seconds by use of an ambulatory pH monitor. There were two 24-hour recordings of intragastric pH for each foal, with 24 hours between recordings. Foals were not administered any drugs during the first recording. Foals were administ...
Hassel DM, Rakestraw PC, Gardner IA, Spier SJ, Snyder JR.A prospective, unmatched case control study was performed to identify dietary and environmental risk factors for enterolithiasis in horses in California and to determine whether colonic ingesta analyses differed between horses with and without enteroliths. Forty-three horses with enterolithiasis were compared with 19 horses with surgical colic attributable to nonstrangulating obstruction of the colon without enteroliths. Colonic ingesta samples were collected at surgery from horses with enteroliths and control horses. Colonic pH and colonic concentrations of magnesium, phosphorus, sulfur, sodi...
Dias AJ, Maia MS, Retamal CA, López ML.The expression of alpha-1,4-glucosidase activity was fluorometrically and electrophoretically assessed in the epididymal fluid and seminal plasma of stallions. alpha-Glucosidase specific activity in the epididymis increased significantly from the proximal caput to the cauda. Stallion epididymal glucosidase maintained activity in a wide range of pH, with two distinct peaks (around pH 4.0 and 6.0, respectively). Enzyme activities at different pH, inhibition assays with sodium dodecyl sulfate (SDS) and maltotriose (MTT, selective inhibitors of alpha-glucosidases "acidic" and "neutral" isoforms, d...
Zeyner A, Geissler C, Dittrich A.To investigate effects of hay intake and feeding sequence on indicators of the microbial activity within the hindgut, six horses were fed 1.00 kg oats plus 0.50, 0.67, 0.83 or 1.00 kg hay/100 kg body weight (BW) x day, each for 14 days. Oats was offered either 30 min prior to hay (OA) or in the reversed sequence (HA) in a 2 x 8-week crossover design. Because typically exercised horses should be subjected to the study, faeces was used as substrate. Faecal dry matter (DM), the faecal waters' short-chain fatty acids (SCFA, in mmol/1) and molar percentages (mol%) of propionate and iso-butyrate wer...
Merritt AM, Sanchez LC, Burrow JA, Church M, Ludzia S.Ulceration of the squamous gastric mucosa is commonly associated with intensive training programmes in horses, but only one compound ('Gastrogard') has been subjected to controlled scrutiny as to therapeutic efficacy. Objective: To compare the gastric acid inhibitory efficacy of one manufactured ('GastroGard') and 3 generic pharmacy-compounded preparations of the proton pump inhibitor omeprazole (OME) in the mature horse. Objective: All OME preparations tested would induce a clinically acceptable effect. Methods: Six healthy mature gastrically cannulated horses of various breeds, 3 mares and 3...
Robinson VL, Smith BB, Arnone A.In 1947, Perutz and co-workers reported that crystalline horse methemoglobin undergoes a large lattice transition as the pH is decreased from 7.1 to 5.4. We have determined the pH 7.1 and 5.4 crystal structures of horse methemoglobin at 1.6 and 2.1 A resolution, respectively, and find that this lattice transition involves a 23 A translation of adjacent hemoglobin tetramers as well as changes in alpha heme ligation and the tertiary structure of the alpha subunits. Specifically, when the pH is lowered from 7.1 to 5.4, the Fe(3+) alpha heme groups (but not the beta heme groups) are converted from...
Frias AF, Mársico F, Gómez de Segura IA, Nascimento PR, Nascimento A, Soares JH, Almosny NR.To characterize responses to different doses of propofol in horses pre-medicated with xylazine. Methods: Six adult horses (five females and one male). Methods: Each horse was anaesthetized four times with either ketamine or propofol in random order at 1-week intervals. Horses were pre-medicated with xylazine (1.1 mg kg-1 IV over a minute), and 5 minutes later anaesthesia was induced with either ketamine (2.2 mg kg-1 IV) or propofol (1, 2 and 4 mg kg-1 IV; low, medium and high doses, respectively). Data were collected continuously (electrocardiogram) or after xylazine administration and at 5, 1...
Malisauskas M, Zamotin V, Jass J, Noppe W, Dobson CM, Morozova-Roche LA.The calcium-binding equine lysozyme has been found to undergo conversion into amyloid fibrils during incubation in solution at acidic pH. At pH 4.5 and 57 degrees C, where equine lysozyme forms a partially unfolded molten globule state, the protein forms protofilaments with a width of ca. 2 nm. In the absence of Ca(2+) the protofilaments are present as annular structures with a diameter of 40-50 nm. In the presence of 10 mM CaCl(2) the protofilaments of equine lysozyme are straight or curved; they can assemble into thicker threads, but they do not appear to undergo circularisation. At pH 2.0, ...
Nadeau JA, Andrews FM, Patton CS, Argenzio RA, Mathew AG, Saxton AM.To identify the pathogenesis of gastric ulcers by comparing injury to the nonglandular gastric mucosa of horses caused by hydrochloric acid (HCl) or volatile fatty acids (VFAs). Methods: Gastric tissues from 30 horses. Methods: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance calculated for tissues after addition of HCl and VFAs to normal Ringer's solution (NRS). Tissues were examined histologically. Results: Mucosa exposed to HCl in NRS (pH, 1.5) had a significant decrease in Isc, co...
Santos M, Fuente M, Garcia-Iturralde R, Herran R, Lopez-Sanroman J, Tendillo FJ.Recovery from inhalant anaesthesia in the horse is a critical and difficult period to manage; however, several factors could help to obtain a calm recovery period including choice of anaesthetic and analgesic procedure used and the conditions under which anaesthetic maintenance and recovery occur. Objective: The objective of this study was to evaluate and compare the quality of recovery in horses administered saline, xylazine, detomidine or romifidine during recovery from isoflurane anaesthesia. Methods: Six mature and healthy horses were premedicated with i.v. xylazine and butorphanol, and an...
Qureshi SH, Moza B, Yadav S, Ahmad F.The denaturation of bovine and horse cytochromes-c by weak salt denaturants (LiCl and CaCl(2)) was measured at 25 degrees C by observing changes in molar absorbance at 400 nm (Delta epsilon(400)) and circular dichroism (CD) at 222 and 409 nm. Measurements of Delta epsilon(400) and mean residue ellipticity at 409 nm ([theta](409)) gave a biphasic transition for both modes of denaturation of cytochromes-c. It has been observed that the first denaturation phase, N (native) conformation X (intermediate) conformation and the second denaturation phase, X conformation D (denatured) conformation are...
Research in microbiologyFebruary 11, 2003
Volume 154, Issue 1 29-35 doi: 10.1016/s0923-2508(02)00003-7
Silva TA, Rodrigues PH, Ribeiro RN, Noronha FS, Farias Lde M, Carvalho MA.The influence of growth medium, hemin and menadione, blood source and atmosphere of incubation on the expression of hemolytic activity of 25 strains of Prevotella intermedia and Prevotella nigrescens was evaluated. The best hemolytic activity was observed for samples of both species growing in brain heart infusion agar and incubated in Brewer-like anaerobic jars for 48 h. Hemolysis was less intense and occurred later in the presence of hemin and menadione in solid media. beta-Hemolysis was detected for medium supplemented with horse or human blood and alpha-hemolysis was observed when sheep bl...
Manohar M, Goetz TE, Hassan AS.It is reported that preexercise hyperhydration caused arterial O(2) tension of horses performing submaximal exercise to decrease further by 15 Torr (Sosa-Leon L, Hodgson DR, Evans DL, Ray SP, Carlson GP, and Rose RJ. Equine Vet J Suppl 34: 425-429, 2002). Because hydration status is important to optimal athletic performance and thermoregulation during exercise, the present study examined whether preexercise induction of hypervolemia would similarly accentuate the arterial hypoxemia in Thoroughbreds performing short-term high-intensity exercise. Two sets of experiments (namely, control and hype...
Fintl C, Milne EM, McGorum BC.To determine whether urinalysis can aid the diagnosis of equine grass sickness, samples of urine from 15 horses with acute grass sickness, eight horses with subacute grass sickness, 17 co-grazing horses and 17 stabled control horses were analysed. The samples from all of the horses with grass sickness had a significantly higher specific gravity, higher protein and creatinine concentrations and a significantly lower pH; the samples from the horses with acute grass sickness also had significantly higher glucose concentrations. These differences may support a diagnosis of grass sickness but they ...
Vervuert I, Coenen M, Wedemeyer U, Chrobok C, Harmeyer J, Sporleder HP.Physical exercise is known to affect calcium homeostasis in horses, but there is little information on the hormonal regulation of calcium metabolism during exercise. In order to evaluate the effects of exercise and training on calcium homeostasis and intact plasma parathyroid hormone, 7 untrained Standardbred horses were studied in a 6 week training programme. These horses were accustomed to running on the treadmill 3 weeks before onset of training and were exercised on a high-speed treadmill with an initial incremental standardised exercise test (SET 1: 6 incremental steps of 5 min duration e...
Lorenzo-Figueras M, Merritt AM.To assess effects of exercise on a treadmill with changes in gastric volume and pH in the proximal portion of the stomach of horses. Methods: 3 healthy adult horses. Methods: A polyester bag of approximately 1,600 mL was placed into the proximal portion of the stomach of each horse via a nasogastric tube. Changes in bag volume, determined by an electronic barostat, were recorded before, during, and after a training session on a treadmill with and without prior withholding of food. In separate experiments, pH in the proximal portion of the stomach was continuously recorded during exercise for f...
Bailey SR, Rycroft A, Elliott J.Acute laminitis can be induced experimentally in horses by the administration of carbohydrate, resulting in fermentation within the cecum and ischemia-reperfusion of the digits. The products of fermentation that trigger acute laminitis are as yet unknown; however, compounds such as amines might play a role due to their potential vasoactive properties. The objectives of this study were to quantify the amines present in equine cecal contents and to use a model of carbohydrate overload in vitro to test the hypothesis that carbohydrate fermentation is associated with increased amine production. Ce...
Medina B, Girard ID, Jacotot E, Julliand V.Eight horses were allotted into pairs consisting of one cecum- and right ventral colon-fistulated animal and one cecum-fistulated animal. They were fed daily at the same level of intake either a high-fiber (HF) or a high-starch (HS) diet without or with 10 g of a Saccharomyces cerevisiae preparation, in a 4 x 4 Latin square design. The HS diet provided a starch overload (i.e., 3.4 g starch x kg(-1) BW x meal(-1)) while maintaining a high amount of fiber intake (i.e., dietary NDF/starch ratio was 1.0). A 21-d period of adaptation to the treatments occurred before cecal and colonic contents were...
Beard LA, Hinchcliff KW.Sodium bicarbonate is often administered to horses before racing in an attempt to delay fatigue and improve performance. We examined the effect of acid-base status on serum ionised calcium concentration (iCa) during high intensity exercise in 8 Standardbred mares. In a randomised, blinded, cross-over study, mares were administered each of 3 treatments, NaCl (0.7 g/kg bwt), NaHCO3 (1 g/kg bwt) in 3 l water, or 3 l of water only, 4 h before performing a standardised exercise test to fatigue on a treadmill. Mixed venous blood samples were collected as the horses ran for 5 min at 3 m/s, to fatigue...
Hoffman RM, Hess TM, Williams CA, Kronfeld DS, Griewe-Crandell KM, Waldron JE, Graham-Thiers PM, Gay LS, Splan RK, Saker KE, Harris PA.To test the hypothesis that endurance performance may be related quantitatively to changes in blood, we measured selected blood variables then determined their reference ranges and associations with speed during an 80 km race. The plan had 46 horses in a 2 x 2 factorial design testing a potassium-free electrolyte mix and a vitamin supplement. Blood samples were collected before the race, at 21, 37, 56 and 80 km, and 20 min after finishing, for assay of haematocrit, plasma pH, pO2, pCO2, [Na+], [K+], [Ca++], [Mg++], [Cl-], lactate, glucose, urea, cortisol, alpha-tocopherol, ascorbate, creatine ...
Zeyner A, Kirbach H, Fürll M.Feeding a high-fat diet may have potential advantages by maintaining pH homeostasis during intense exercise; conversely, effects including elevated PCV and increased plasma concentration of total protein may indicate effects detrimental to performance by reducing perfusion of tissues and organs. Six horses were used to determine the effects of an replacement of starch (diet '0.00') with 0.33, 0.67, 1.00 and 1.33 g soybean oil/kg bwt/day (diets '033', '0.67', '1.00' and '1.33') on venous and renal acid-base status and fractional clearance (FC) of electrolytes in a postprandial state but prior t...
Silverman SC, Birks EK.This study examined the accuracy and precision of a hand-held, chemical analyser, i-STAT, in measuring selected blood constituents which may be of use in the diagnosis and management of metabolic disorders found in exercising horses. Venous blood samples were taken from 3 Thoroughbred geldings, fit and trained to exercise on a treadmill, both before and after exercise at a speed sufficient to elicit VO2max. The samples were analysed both with the i-STAT and with in-house analysers to compare the values of pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), bicarbon...
Schuback K, Essén-Gustavsson B, Persson SG.Administration of bicarbonate has been shown to cause metabolic alkalosis both in man and in horses and is, therefore, thought to increase the buffering capacity of the body and thereby delay the onset of fatigue. However, results regarding the influence of sodium bicarbonate loading on performance both in human athletes and in horses are conflicting. The aim of this study was, therefore, to investigate the metabolic response to a standardised treadmill exercise test to fatigue, in horses given bicarbonate (0.6 g/kg bwt), in comparison to horses given placebo (water). Five Standardbred trotter...
Paynter S, Russell DA.Recently, the observation of pH-induced conformational changes of biomolecules supported on carboxymethyldextran (CMD)-coated surfaces measured using surface plasmon resonance (SPR) has been reported. However, it is apparent that the evidence reported in the literature is ambiguous. The research presented in this paper describes investigations to study the changing SPR signal of immobilized biomolecules as a function of varying pH, to provide a detailed understanding of the origin of the pH-induced changes in the SPR profile. SPR measurements were performed with cytochrome c, concanavalin A, a...
van der Kolk JH, Nachreiner RF, Refsal KR, Brouillet D, Wensing T.Our objectives were to 1) establish ionised calcium (ICa), C-terminal PTH and biologically active PTH (intact molecule) concentrations in blood from normal horses, 2) examine the stability of ionised calcium and acid-base values in stored equine heparinised blood and serum and 3) check the applicability of the formulas based on these parameters in certain disease states. Mean +/- s.d. % ionised calcium in heparinised blood of normal Warmbloods was 51 +/- 2.7 (n = 20) of total calcium, range 1.45-1.75 mmol/l (n = 15) at Michigan State University and 1.43-1.69 mmol/l (n = 20) at Utrecht Universi...
Tsekova D, Popova S, Nanev C.The nucleation of horse spleen ferritin (HSF) crystals on substrates was investigated using a new modification of the double pulse technique. The influence of three different structureless substrates (glass, glass covered by methyl groups and poly-L-lysin template) on the nucleation was studied. The boundaries in the phase-diagram, which separate zones of crystal nucleation and growth were obtained by keeping pH = 5.0, and using CdSO(4) as crystallizing agent. The steady-state nucleation rates were determined. The energy required for critical nuclei formation was evaluated (10(-13) erg) and th...
Widenhouse TV, Lester GD, Merritt AM.To determine the effect of pH with or without pepsin or taurocholic acid on the bioelectric properties of gastric squamous mucosa in horses. Methods: Gastric tissues obtained from 16 adult horses that did not have evidence of gastric disease. Methods: Bioelectric properties of squamous mucosa were determined, using modified Ussing chambers. Tissues then were exposed to mucosal pepsin (1 mg/ml) or taurocholic acid (2.5 mM) under neutral (pH 74) or acidic (pH 1.7) conditions. Results: Exposure of mucosal sheets to an acidic pH resulted in an immediate and sustained decrease in transmembrane pote...
Dorneles TEA, Costa Junior JD, Almeida RM, Teixeira Neto AR.Anaerobic cellular metabolism causes a series of structural and physiologic changes during storage that could compromise post-transfusion viability, reducing the safety of using blood stored for an extended period. Objective: We aimed to follow the biochemical and hematologic alterations of equine blood stored in plastic bags containing citrate-phosphate-dextrose-adenine (CPDA-1) for up to 28 days. Methods: Whole blood samples (450 mL) were collected from 20 Brazilian Saddle horses into CPDA-1 pouches and stored between 2°C and 6°C in a blood bank. On days 0, 7, 14, 21, and 28 of storage, ...
Vitello LB, Erman JE.The binding of horse heart cytochrome c to yeast cytochrome c peroxidase in which the heme group was replaced by protoporphyrin IX was determined by a fluorescence quenching technique. The association between ferricytochrome c and cytochrome c peroxidase was investigated at pH 6.0 in cacodylate/KNO3 buffers. Ionic strength was varied between 3.5 mM and 1.0 M. No binding occurs at 1.0 M ionic strength although there was a substantial decrease in fluorescence intensity due to the inner filter effect. After correcting for the inner filter effect, significant quenching of porphyrin cytochrome c pe...
Kalantari RK, Rouzbehan Y, Fazaeli H, Direkvandi E, Salem AZM.The aim of this study was to investigate, the effect of different levels of concentrates and grain processing on feeding behavior, nutrient digestibility, fecal pH and blood metabolites in the horse. Sixteen 5 to 11 years old Turkmen horses with an initial body weight 433±50 kg were used in this experiment based on completely randomized design. Four treatments were studied, in three treatments were used 20, 25 and 30% of concentrate containing processed grains (A20, A25 and A30, respectively), and in one treatment was used 25% of concentrate containing whole grain (B25). The amount of feed in...
Sanchez LC, Murray MJ, Merritt AM.To evaluate the efficacy of omeprazole paste, a commonly used antiulcer drug, on intragastric pH in clinically normal neonatal foals. Methods: 6 clinically normal foals between 5 and 14 days of age. Methods: Intragastric pH was recorded in each foal by use of a disposable antimony pH electrode with internal reference. Values for intragastric pH were recorded every 4 seconds by use of an ambulatory pH monitor. There were two 24-hour recordings of intragastric pH for each foal, with 24 hours between recordings. Foals were not administered any drugs during the first recording. Foals were administ...
Shirer HW, Erichsen DF, Orr JA.Previous reports indicate that intravenous infusion of HCl can alter breathing and blood pressure even if reductions in systemic arterial pH are prevented. To extend these findings, as well as to determine whether other acids elicit comparable results, this report compares the cardiopulmonary response between right atrial infusion of lactic acid and HCl in awake ponies. Lactic acid, infused at a dose of 1.5 mmol/kg over 18 min, lowered systemic and pulmonary arterial pH 0.062 and 0.092 U, respectively, and increased pulmonary arterial pressure (delta Ppa, 4 mmHg), heart rate (HR, 4/min), and t...
Munsterman AS, Dias Moreira AS, Marqués FJ.Wei Le San (WLS) is a Chinese herbal formula comprised of 9 herbs selected for their putative anti-inflammatory effects. Objective: To evaluate the effects of WLS administration in horses with nonglandular gastric ulcers. Methods: Ten mixed breed mares (aged 7-21 years, 401-567 kg body weight). Methods: Experimental design was a blinded, prospective, 2-period crossover study. All horses received a placebo (25 mL dextrose-based syrup; n = 10) and the treatment (WLS, 5 g in 25 mL dextrose-based syrup; n = 10), administered twice daily. Horses underwent a 1-week, alternating feed-depriv...
Silver M, Fowden AL.In the present study, ten insulin challenge tests were carried out on nine chronically catheterized fetal foals between 253 and 314 days gestation (term > 320 days). Changes in fetal plasma concentrations of glucose, catecholamines, cortisol, ACTH, free fatty acid (FFA) and lactate were measured before and after a bolus dose of insulin (0.5-2.0 u/kg I.V.). Fetal blood gases, pH, haemoglobin levels and heart rate were measured throughout the 2-3h experimental period. The fetuses fell into two distinct groups on the basis of proximity to delivery and basal plasma cortisol and catecholamine level...
Looze Y, Polastro E, Deconinck M, Leonis J.Spectrophotometric studies of the alkaline isomerization of horse heart and yeast cytochrome c show that the haemoproteins from Saccharomyces cerevisiae differ significantly from the mammalian cytochrome c. Apparent pKa values of 8.41, 8.40 and 8.73 for isol-1-(the methylated and unmethylated forms) and iso-2-cytochrome c respectively, from baker's yeast were determined and compared with the value of 9.40 found for horse heart cytochrome c. The transitions, measured by observing the decrease of the absorbance at 695 nm as the pH increases, have been found to strictly parallel the decrease in a...
Nakagawa K, Yamada Y, Fujiwara K, Ikeguchi M.Equine beta-lactoglobulin forms a compact intermediate at an acidic pH (A state). It also forms an expanded and helical conformation at low temperatures (C state). The structure of a single disulfide mutant C66A/C160A is similar to the A state in the presence of salts, while it is similar to the C state at low anion concentrations. We have investigated the temperature-dependent change in the secondary structure using circular dichroism and proline scanning mutagenesis. At low anion concentrations, the helical content increased linearly as temperature decreased. In the presence of salts, the A ...
Silver IA.Wound healing is part of the normal general repair process of the body. Its efficient completion depends on many factors, some physical, eg, pH, oxygen tension and tissue tension, and some biological, eg, cell-cell interaction and feedback of extracellular matrix on to the cells which produce it. The factors which affect healing are discussed and failures and anomalies in the process described. New techniques which may improve the quality of healing in specialised tissues are explained. Recent research on wound healing has concentrated on the role of the different cell types in the process and...
Hess TM, Kronfeld DS, Williams CA, Waldron JN, Graham-Thiers PM, Greiwe-Crandell K, Lopes MA, Harris PA.To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with commercial potassium-rich mixtures (EM+K) on acid-base status and plasma ion concentrations in horses during an 80-km endurance ride. Methods: 46 healthy horses. Methods: Blood samples were collected before the ride; at 21-, 37-, 56-, and 80-km inspection points; and during recovery (ie, 30-minute period after the ride). Consumed electrolytes were recorded. Blood was analyzed for pH, PvCO2, and Hct, and plasma was analyzed for Na+, K+,...
Jensen RB, Brokner C, Knudsen KE, Tauson AH.Four Icelandic (ICE) and four Danish Warmblood (DW) horses were used in a crossover study with two treatments to investigate the effect of breed and the effect of stage of maturity of haylage on the apparent total tract digestibility (ATTD) of a diet consisting of sugar beet pulp, black oats and haylage early or late cut. Fibre was analysed as crude fibre (CF), acid detergent fibre (ADF), neutral detergent fibre (NDF) and dietary fibre (DF = non-starch polysaccharides (NSP) plus lignin). In haylage all analysed fibre fractions increased with advancing stage of maturity, with the cell wall comp...
Ward PL, Wohlt JE, Katz SE.Two experiments were conducted comparing pelleted recycled newspaper (PN) to wheat straw (S) and kiln-dried pine wood shavings (WS) as an animal bedding material. Adult horses housed 20 to 21 h/d in boxstalls served as the animal model for comparisons. In Exp. 1 eight boxstalls, each housing one horse, were each bedded with two types of PN (0.32 and 0.64 x 2.54 cm), S, and WS over four 5-d periods (replicated 4 x 4 Latin square). Initial amounts of bedding materials surpassed most commercial conditions, but stalls were cleaned daily of feces only and additional clean bedding was added as neede...
Adler DM, Cornett C, Damborg P, Verwilghen DR.Local anaesthetics (LAs) are frequently used for diagnostic procedures in equine veterinary practice. The objective of this study was to investigate the physico-chemical stability and bacterial contamination of bupivacaine, lidocaine and mepivacaine used for lameness examinations in horses. The LAs were stored in 12 different groups at different temperatures (-18 °C to 70 °C), light intensities and in common veterinary field conditions for up to 16 months. The pH, presence of bacterial contamination and concentrations of LAs and methylparaben (a preservative present in lidocaine) were de...
Hekmatynia F, Eskandarzadeh N, Imani M, Rezaei M, Zamani-Ahmadmahmudi M.Urinalysis is a critical diagnostic test which is performed in routine veterinary medicine practice. In this diagnostic test, semiquantitative measurement of urine biochemical substances is carried out using urinary dipstick. In the current study, we evaluated the diagnostic performance of human urinary dipsticks to estimate pH, specific gravity (SpG), and protein in 80 urine specimens collected from horses. These parameters were measured using two commercial human dipsticks (KP and MN in abbreviation) and quantitative reference methods. The reference methods for pH, SpG, and protein were pH m...
Waller AP, Lindinger MI.Oral electrolyte supplementation may influence acid-base state during exercise due to the intestinal absorption of administered water and electrolytes used to mitigating sweat losses. This study examined the effect of pre-exercise electrolyte supplementation (3 and 8 L) on plasma acid-base variables at rest, during moderate intensity exercise and during recovery. It was hypothesized that electrolyte supplementation will result in improved acid-base state compared to the alkalosis typical of prolonged exercise. In randomized crossover fashion, four horses were administered 3 L or 8 L of a hypot...
Haouz A, Glandieres JM, Zentz C, Pin S, Ramstein J, Tauc P, Brochon JC, Alpert B.The effects of the solvent conditions (buffer pH 9, 8, or 7 or buffer pH 6.5 alone or mixed with 3.2% ethanol or 6.2% formamide) on the protein dynamics of horse apomyoglobin were investigated through tryptophan fluorescence quenching, spectra, and decay properties. Raising the pH (which induces discontinuous protein conformation changes) increases the structural fluctuations inside the hydrophobic A, G, and H helix core. Mixed solutions containing either 3.2% ethanol or 6.2% formamide (which redistribute water molecules on the protein surface) produce protein dynamics changes in the vicinity ...
Sanmartí J, Robles-Guirado JA, Jose-Cunilleras E, Bassols A.The determination of iCa and iMg is important in veterinary medicine, but their immediate determination in whole blood is not always possible. Their stability in other sample types and the existence of interferences must be evaluated before its use. Objective: We aimed to analyze the effects of storage time on the stability of iCa, iMg, and other analytes in whole blood, plasma, and serum samples in horses and assess the interference of heparin in these measurements. Methods: Whole blood, heparin-plasma, and serum samples from 10 horses were stored at 4°C and analyzed 1, 2, 3, 4, 5, 6, 7, 8, ...
Matsumura Y, Li J, Ikeguchi M, Kihara H.Acidic buffer conditions are known to stabilize helix-rich states of even those proteins with a predominantly beta-sheet native secondary structure. Here we investigated whether such states also exist under alkaline buffer conditions. The guanidine hydrochloride (GuHCl)-induced unfolding transition and kinetic refolding of equine beta-lactoglobulin (ELG) by GuHCl-jump were investigated at pH 8.7 by far-ultraviolet circular dichroism. We found that an equilibrium intermediate appeared in 45% ethylene glycol (EGOH) buffer with 1.5 M GuHCl. The intermediate is rich in non-native alpha-helix, whic...
Marichal G, Trigo P, Soto C, Meikle A, Suárez G.The Raid Uruguayo (RAID) is an equestrian endurance competition. This study characterized the hydroelectrolytic parameters (Na, K, Cl, tCa, and iCa), hematocrit (Ht), total plasma protein (TPP), and blood pH from 900 equine athletes (finishers and non-finishers) competing over distances of 80 to 115 km under different climate conditions. Paired blood samples were taken prior to the start of the competition (sample 1) and at the end of the race or at the time of leaving the competition (sample 2). The association of the comfort index (CI: low, moderate, and high) with blood parameters was evalu...
Korkeala H, Stabel-Taucher R, Pekkanen TJ.When 33 horse kidneys were tested for the presence of inhibitory substances by the Bacillus subtilis BGA method at pH 8 and the Micrococcus luteus ATCC 9341 method, 24 were positive and 9 negative. The pH of the seeded M. luteus test medium changed from pH 6.6 before incubation to 8.7 after 24 hours incubation at 30 degrees C. When the same 33 kidneys were tested by the B. subtilis BGA method, medium pH 6, and 15 of them also by the M. luteus method using a medium buffered to pH 6, all were negative. The cadmium concentration of the 33 horse kidneys was found to be 70.17 +/- 81.28 mg/kg wet we...
Bauck AG, Vidyasagar S, Freeman DE.To examine bicarbonate (HCO3-) secretion ex vivo in the equine large colon to determine any differences between the right dorsal colon (RDC) and right ventral colon (RVC). The effect of phenylbutazone (PBZ) on HCO3- secretion was examined in the RDC. Methods: 14 healthy horses. Methods: In anesthetized horses (n = 10), segments of mucosa from RDC and RVC were harvested to measure HCO3- secretion ex vivo with the pH Stat method. The effect of PBZ on HCO3- secretion in the RDC was studied in 4 additional horses. Results: Three distinct mechanisms of HCO3- secretion previously described in a muri...
Milner PI, Smith HC, Robinson R, Wilkins RJ, Gibson JS.Hypoxia and acidosis are recognized features of inflammatory arthroses. This study describes the effects of IGF-1 and TGF-β(1) on pH regulatory mechanisms in articular cartilage under hypoxic conditions. Acid efflux, reactive oxygen species (ROS), and mitochondrial membrane potential were measured in equine articular chondrocytes isolated in the presence of serum (10% fetal calf serum), IGF-1 (1, 10, 50, 100 ng/ml) or TGF-β(1) (0.1, 1, 10 ng/ml) and then exposed to a short-term (3 h) hypoxic insult (1% O(2)). Serum and 100 ng/ml IGF-1 but not TGF-β(1) attenuated hypoxic regulation of pH hom...
Tsekova D, Popova S, Nanev C.The nucleation of horse spleen ferritin (HSF) crystals on substrates was investigated using a new modification of the double pulse technique. The influence of three different structureless substrates (glass, glass covered by methyl groups and poly-L-lysin template) on the nucleation was studied. The boundaries in the phase-diagram, which separate zones of crystal nucleation and growth were obtained by keeping pH = 5.0, and using CdSO(4) as crystallizing agent. The steady-state nucleation rates were determined. The energy required for critical nuclei formation was evaluated (10(-13) erg) and th...
Sojka JE, Weiss JS, Samuels ML, You GM.The effect of the somatostatin analogue, octreotide, on gastric fluid pH was investigated in 4 ponies. Gastric fluid pH was determined after SC administration of octreotide or physiologic saline solution (control). A baseline sample of fluid was obtained, the agent was given, and 8 additional samples were collected hourly. Administration of octreotide at all dosages tested (0.1, 0.5, 1.0, and 5.0 micrograms/kg of body weight) increased gastric pH to > 5.0. Baseline values were consistently 4.0 for 2.4 +/- 1.2, 4.8 +/- 0.8, 5.7 +/- 1.3, and 5.4 +/- 2.6 (mean +/- SD) continuous hours, respec...
Kumar R, Prabhu NP, Bhuyan AK.Laser flash photolysis and stopped-flow methods have been used to study the dynamic events in the micro- to millisecond time bin in the refolding of horse ferrocytochrome c in the full range of guanidine hydrochloride concentration at pH 12.8 (+/-0.1), 22 degrees C. Under the absolute refolding condition, the earliest relaxation time of the unfolded protein chain is less than 1 micros. The chain then undergoes diffusive dynamics-mediated contraction and expansion, in which intrapolypeptide ligands make transient contacts with the heme iron, giving rise to two distinct kinetic phases of approxi...
Matoba H, Allen JR, Bayly WM, Oakley CR, Gollnick PD.Comparisons were made of the histochemical characteristics of skeletal muscle from 10 animal species. The basic comparison was made from the staining patterns for the myofibrillar actomyosin ATPase produced by preincubation of fresh frozen cross-sections of muscle at alkaline pH (10.30) or acid pH (4.60) with those produced by preincubation in media containing Cu2+ at alkaline pH (10.30), near neutral pH (7.40), or acid pH (4.60). Muscle sections were also stained for reduced nicotinamide adenine dinucleotide tetrazolium reductase and alpha-glycerophosphate dehydrogenase to provide an indicati...
Peterman BF, Morton RA.The apparent equilibrium constant and rate of oxidation was investigated for the reaction of cytochrome c with iron hexacyanide. It was found that if horse heart ferricytochrome c was exposed to ferricyanide (to oxidize traces of reduced protein) the cytochrome subsequently, even after extensive dialysis, had an apparent equilibrium constant different from that of electrodialyzed protein. The effect of ferricyanide ion apparently cannot be removed by ordinary dialysis. The ionic strength dependence of the apparent equilibrium constant and bimolecular oxidation rate constant was measured in the...
Deane JC, Dagleish MP, Benamou AE, Wolf BT, Marlin D.To evaluate the consistency of partial pressures (P) of arterial oxygen (aO(2)), arterial carbon dioxide (aCO(2)) and pH measurements in equine carotid arterial blood samples taken into syringes made from three different materials and stored at room temperature or placed in iced water for measurement at three different times. Methods: Prospective observational study over 19 days. Methods: Four clinically normal Thoroughbred or Thoroughbred-cross horses (three geldings, one mare, mean age 6.25 years, range 5-7 years). Methods: Identical blood samples were taken on two separate occasions from th...
Huxford KE, Dart AJ, Perkins NR, Bell R, Jeffcott LB.AIMS To compare the efficacy of an enteric coated esomeprazole paste with an enteric coated omeprazole paste to increase gastric pH after oral administration in horses. METHODS Nine adult Standardbred horses were randomly assigned to three groups, each containing three horses, for a study comprising three phases of 10 days, with an 18-day washout period between each phase. In each phase, three horses received either 0.5 mg/kg esomeprazole, 1 mg/kg omeprazole or a placebo, as an oral paste, once daily for 10 days (Days 0-9). Over the course of study all horses received all three treatments....
