Sodium is an essential electrolyte in horses, involved in maintaining fluid balance, nerve function, and muscle contraction. It plays a significant role in the regulation of osmotic pressure within cells and the overall homeostasis of bodily fluids. Horses obtain sodium primarily through their diet, and it can be supplemented through salt blocks or electrolyte solutions, especially in cases of heavy sweating or increased physical activity. Imbalances in sodium levels, either deficiency or excess, can impact a horse's health and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the metabolism, dietary requirements, and physiological effects of sodium in equine health.
Lloyd DR, Rose RJ.Sodium bicarbonate given by nasogastric tube has been used by some trainers as the key ingredient in a 'milkshake'. It has been suggested that such treatment given 3-5 h prior to racing may enhance a horse's racing performance by increasing the blood buffering capacity and enhancing lactate clearance from skeletal muscle, thereby delaying the onset of fatigue. Several experiments were conducted to examine the effects on fluid, electrolyte and acid-base values of 0.5 g kg-1 dose of sodium bicarbonate, were examined. The effects of fasting, the simultaneous administration of glucose (0.5 g kg-1)...
Mealey RH, Carter GK, Roussel AJ, Ruoff WW.Two different fluid solutions were infused through percutaneous cecal catheters in 6 healthy ponies to determine the effects on body weight; CBC; packed cell volume (PCV); total plasma protein concentration; plasma fibrinogen concentration; abdominal fluid analysis; concentrations of blood urea nitrogen (BUN), serum creatinine, Ca, total CO2 (TCO2), Na, Cl, K, and P; and fractional clearance (FC) of Na, Cl, K, and P. During intracecal administration of solution 1, FCNa and FCCl were significantly increased, whereas FCK and BUN were significantly decreased. During administration of solution 2, ...
Taylor LE, Ferrante PL, Kronfeld DS, Meacham TN.Seven Arabian horses performed a standard incremental exercise test on a high-speed treadmill at 6% slope then were randomly assigned to two diets, a control diet of ground hay and concentrates and a similar diet with 10% added fat (by weight). Horses were sprint-trained 4 d/wk, and two additional exercise tests were performed at 5-wk intervals. Heart rates and rectal temperatures were monitored and venous blood samples were collected at rest and at each speed increment. Whole blood was analyzed for glucose, lactate, and hemoglobin concentrations, and plasma was analyzed for pH, pCO2, albumin,...
Cannon SC, Hayward LJ, Beech J, Brown RH.1. Equine hyperkalemic periodic paralysis (E-HPP) is a dominantly inherited disorder of muscle that causes recurrent episodes of stiffness (myotonia) and weakness in association with elevated serum K+. Affected horses carry a mutant allele of the skeletal muscle isoform of the Na channel alpha-subunit. To understand how this mutation may cause the disease phenotype, the functional defect in Na channel behavior was defined physiologically by recording unitary currents from cell-attached patches on normal and affected equine myotubes. 2. The presence of the mutation was confirmed in our cell lin...
Frey LP, Kline KH, Foreman JH.Analysis of data collected at racetracks showed that temperature, the diuretic drug, frusemide, exercise, temperature/exercise interaction and sex/age had significant (P < 0.05) effects on pH and bicarbonate ion concentration (P < 0.01). Sodium concentrations were significantly (P < 0.001) affected by temperature and frusemide. We suggest that the normal range limits for blood sodium, bicarbonate and pH used in prerace testing procedures should be adjusted for ambient temperature and for horses given frusemide and/or prerace exercise. These adjustments should improve the precision of ...
von Engelhardt W, Rösel E, Rechkemmer G.Short circuit current (ISC) and transepithelial conductance (gt) across sheets of epithelia were measured in the caecum, the proximal and the distal colon of pig, sheep, pony, rat and guinea pig. The electrical parameters underline the basic segmental and species differences. The diversity of ISC demonstrates the different nature of electrogenic transport mechanisms, and data clearly show the heterogeneity with respect to transport mechanisms along the large intestine in the various species. The great differences in amiloride sensitive ISC indicate the variabilities in the electrogenic Na tran...
Mueller PO, Hunt RJ, Allen D, Parks AH, Hay WP.The effect of intraperitoneal sodium carboxymethylcellulose (SCMC) administration on clinical outcome and survival was evaluated in horses undergoing exploratory celiotomy for acute gastrointestinal disease. Comparison of variables was made retrospectively between 44 horses that had SCMC and 92 horses (controls) not treated with SCMC. Mean age, body weight, heart rate, packed cell volume and plasma total protein of horses at admission, and convalescent period were not significantly different between control and SCMC groups. No significant differences were noted between control horses and SCMC ...
Barlet JP, Davicco MJ, Coxam V.Intestinal absorption of inorganic phosphorus. In most mammalian species inorganic phosphorus (P) is absorbed at the duodenal and jejunal level. However in horses some P is absorbed from the large intestine, whereas in ruminant animals some absorption also takes place in the forestomachs. The structure of the putative phosphate-sodium carrier of the brush border from enterocytes still awaits identification. P absorption is modulated both by endocrine (calcitriol, triiodothyronine) and nutritional factors (minerals of the diet, chemical form of phosphorus). Regulation of salivary P secretion, i...
Sammut EB, Kannegieter NJ.Intra-articular injection of sodium monoiodoacetate (MIA) was investigated as an agent for chemical arthrodesis of the distal hock joints in the horse. Five horses diagnosed with either spavin (three horses), a small tarsal bone fracture or a failed surgical arthrodesis, had 150 mg of MIA injected into the tarsometatarsal (TMT) joint of the affected hock(s). Eight joints were treated in the five horses. Follow-up evaluation by clinical and radiological examination took place over 9 to 14 months. Two of the five horses were sound at the conclusion of the study and one horse, although lame after...
Hoffman EP.The pathological genetic defects in the inherited myotonias and periodic paralyses were recently elucidated using molecular genetic studies. These disorders are usually transmitted as a dominant trait from an affected parent to a child. The many clinical symptoms include cold-induced uncontrollable contraction of muscle, potassium-induced contraction and paralysis, myotonia with dramatic muscular hypertrophy, muscle stiffness, and insulin-induced paralysis (in males). Horses afflicted with the disorder can suddenly collapse, despite an impressive physique. In the past three years, these clinic...
van der Kolk JH.A 2-year-old Friesian mare was examined because she had been sluggish for a few weeks. Blood biochemistry showed that concentrations of creatinine (136 mumol.L-1) and urea nitrogen (6.1 mmol.L-1) in plasma were within their normal limits. Severe metabolic acidosis was apparent; the venous pH was 7.154 and the bicarbonate concentration was 13 mmol.L-1. The base excess amounted to -15.3 mmol.L-1 and the venous pCO2 measured 5.1 kPa. Plasma sodium was normal (135 mmol.L-1) and plasma chloride (113 mmol.L-1) was slightly elevated, but there was a hypokalaemia (2.9 mmol.L-1). The urine had a specif...
Ferrante PL, Kronfeld DS.Collection of a satisfactory blood sample requires special procedures to prevent changes in glucose and lactate content after the sample has been obtained. Changes in measured plasma glucose and blood lactate concentrations attributable to anticoagulants and storage procedures, respectively, were examined in blood samples obtained from horses at rest and after exercise. To evaluate the effect of anticoagulants on measured plasma glucose concentration, blood was preserved with either sodium fluoride/potassium oxalate or lithium heparin. Measured plasma glucose concentration in blood obtained at...
Abass BT, Weaver BM, Staddon GE, Waterman AW.The pharmacokinetics of thiopentone sodium administered intravenously as a single dose (11 mg/kg) were studied in acepromazine pre-medicated horses and ponies in which anaesthesia was maintained with either halothane (Group 1) or isoflurane (Group 2). The results showed that the disposition kinetics of thiopentone in horses and ponies were best described by a three-compartment open model. In plasma, a very short initial distribution phase in both horses and ponies, half-life 1.4 +/- 1.2 min (mean +/- SD) and 1.3 +/- 0.7 min, respectively, was obtained, which was followed by a second comparativ...
Zhou J, Spier SJ, Beech J, Hoffman EP.It is often suggested that polygenic or environmental factors are responsible for clinical variability between patients with identical mutations. However, most dominant diseases are caused by a change-of-function alteration in the mutant allele's protein product. All patients are heterozygous and presumably express both mutant and normal proteins from the corresponding genes. Thus, a possible molecular mechanism for clinical variability could be the difference in relative levels of mutant vs. normal mRNA in different patients with the same mutation. To investigate this hypothesis, it is necess...
Andrews FM, Ralston SL, Sommardahl CS, Maykuth PL, Green EM, White SL, Williamson LH, Holmes CA, Geiser DR.Body weight of 48 horses competing in a 3-day event was measured the day before the event (baseline), following the dressage phase of the event (day 1), after the endurance phases of the event (day 2), and 18 to 24 hours after the endurance phases (day 3). Plasma sodium and potassium concentrations were measured the evening before, immediately after, and 10 minutes after the endurance phases. Total body water, water loss, and net exchangeable cation loss were then calculated. Body weight and total body water were significantly decreased, compared with baseline values, at all times during the e...
Geor RJ, Weiss DJ, Smith CM.Hemorheologic alterations induced by incremental treadmill exercise were examined in 5 Thoroughbreds. Blood viscosity; PCV; RBC filterability, density gradient profile, and shape; serum and RBC electrolyte concentrations; and plasma total solids and lactate concentrations were measured before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise. Exercise was associated with significant (P < 0.05) increases in PCV, blood viscosity, and plasma total solids concentration. After adjustment of PCV to 40% by adding or removing each horse's own plasma, blood viscosity ...
Hare JE, Viel L, O'Byrne PM, Conlon PD.Some young horses with clinical signs of small airway disease demonstrate increased metachromatic cell numbers on bronchoalveolar lavage. The purpose of this study was to determine the effect of sodium cromoglycate treatment on clinical signs, bronchoalveolar lavage cytology and bronchoalveolar lavage histamine parameters in these horses. Twelve racehorses (age: 3.4 +/- 1.6 years) with a history of respiratory embarrassment at exercise, clinical signs of obstructive airway disease and bronchoalveolar lavage metachromatic cell differential greater than 2% were selected. Horses were randomly ass...
Furr MO, Bender H.To determine the effects of age on each analyte, CSF variables were evaluated in healthy foals from birth through 42 days of age. Cerebrospinal fluid was collected from 14 clinically normal, naturally delivered cross-bred foals and was analyzed for glucose, sodium, potassium, magnesium, and total protein concentrations, total and differential WBC counts, RBC count, and lactate dehydrogenase, aspartate transaminase, and creatine kinase activities. Samples were collected in 3 foals < 48 hours old, and at 11 to 14 days of age in 4 foals, 21 to 22 days of age in 3 foals, and 31 to 42 days of ag...
Naylor JM.The purpose of this review is to present an up-to-date summary of the signs, diagnosis, treatment, and implications of equine hyperkalemic periodic paralysis. The review encompasses all original articles published between 1986 and early 1993. Hyperkalemic periodic paralysis is the result of a genetic mutation in the skeletal muscle sodium channel gene. It is inherited as an autosomal dominant trait; most affected horses are heterozygotes. The classical signs are muscle fasciculation, spasm, and weakness associated with hyperkalemia. However, these signs are only rarely observed in affected hor...
Hejłasz Z, Nicpoń J, Czerw P.Sweat secretion was analyzed quantitatively and qualitatively in 20 horses after a 5 min. gallop at 450 m/min. The analysis revealed concentration of proteins 63.3 +/- 6.47 g/l, mainly albumins, a high level of sodium 254.43 +/- 62.84 mM/,l chloride 268.68 +/- 98.46 mM/l, potassium 98.95 +/- 49.62 mM/l and calcium 4.14 +/- 0.8 mM/l. A dependence was found between the protein concentration in serum and its quantity in sweat and between the level of potassium in sweat and its loss from the cells within a range 8.6 to 25.8 mM/l. The hypertonic horse sweat protects organism for excessive water los...
Todhunter RJ, Wootton JA, Altman N, Lust G, Minor RR.Collagen type I and type II were purified from equine flexor tendon and articular cartilage, respectively. Equal amounts of these collagens were cleaved with cyanogen bromide, and 11 mixtures containing increasing proportions of type II collagen were separated in seven identical sodium dodecyl sulfate-polyacrylamide gels. The density of bands was measured in wet gels and the peak areas were used to form six ratios of peptide bands that had polynomial relationships with the known proportions of type I and type II collagen in the mixtures. Calibration curves for determining the proportion of typ...
Schott HC, Hinchcliff KW.In an attempt to enhance performance, primarily by delaying the onset of fatigue, a variety of formulations of fluids, electrolytes, and sodium bicarbonate are administered to performance horses. Some current practices of fluid and electrolyte supplementation are well justified; others have no basis to support their use. In addition, occasional combined administration of certain agents (i.e., furosemide and sodium bicarbonate) can have detrimental effects on performance.
Naylor JR, Bayly WM, Schott HC, Gollnick PD, Hodgson DR.The effects of dehydration and 40 min of exercise at approximately 40% of maximal O2 consumption on plasma volume (PV) and blood volume (BV) were studied in six horses. Horses were exercised while euhydrated (C); 4 h after administration of furosemide (1.0 mg/kg i.v.; FDH), which induced isotonic dehydration; and after 30 h without water (DDH), which caused hypertonic dehydration. Dehydration resulted in decreases of 6.3 and 9.9% for PV and BV, respectively, with FDH and 10.7 and 8.5%, respectively, with DDH. During exercise in C, PV and BV increased by 12.7 and 20.0%, respectively; during exe...
Beech J, Lindborg S, Braund KG.Potassium concentrations were measured in semimembranosus muscle, plasma and erythrocytes, and the urinary fractional excretion determined in normal horses and those that had chronic intermittent exercise-associated rhabdomyolysis. Muscle from the rhabdomyolysis horses was also evaluated microscopically. The horses with rhabdomyolysis had a lower muscle potassium concentration on a dry weight basis. Although the wet weight potassium content was also lower, the difference was not significant. Urinary fractional excretion of potassium (and also sodium and chloride) did not differ significantly b...
Roussel AJ, Cohen ND, Ruoff WW, Brumbaugh GW, Schmitz DG, Kuesis BS.Saline or glucose solution was infused for approximately 4 hours into six healthy mares in two separate experiments to determine the effect of infusion of crystalloid solutions on fractional excretion (FE) of sodium (Na), chloride (Cl), potassium (K), and phosphorus (P), ratio of urinary creatinine to serum creatinine (UCr/SCr), and ratio of urinary osmolality to serum osmolality (Uosm/Sosm). After intravenous infusion of either saline or glucose solution, FENa, FECl and FEP were significantly increased, whereas UCr/SCr and Uosm/Sosm were significantly decreased. In addition, FEK was significa...
McKeever KH, Hinchcliff KW, Reed SM, Robertson JT.Six intact and 6 splenectomised mares were given an incremental exercise test on a treadmill to examine the fluid and electrolyte changes associated with exercise and the role of the spleen in these changes. Blood samples were obtained at rest and at the end of each 1-min step of the test. Exercise at 7 m/sec caused significant (P 0.05) in either group (intact = 2.7%; splenectomised, = 3.5%). This appears to be the first record of substantial changes of these constituents during short-term exercise, even before the onset of visible sweat losses. The changes in the concentration of plasma prot...
Harris PA.The effect of feeding diets with low, adequate and high sodium contents on plasma aldosterone concentrations in horses and ponies was evaluated using human immunoassay kits. The effect of moderate to high intensity exercise of up to six minutes duration on plasma aldosterone concentrations in three thoroughbred horses was also investigated. On an adequate sodium diet plasma aldosterone concentrations increased to a peak around four hours after feeding. Little daily variation was found in the pre-feeding aldosterone concentrations over three days. Feeding additional salt resulted initially in n...
Geor RJ, Lund EM, Weiss DJ.Retrospective review of CBC and serum chemical data from 124 horses admitted to the veterinary teaching hospital over a 9-month period (Feb 1, 1990 to Oct 31, 1990) indicated that 54 horses had echinocytosis (prevalence = 44%). In horses with echinocytosis, the most frequent diagnosis was colitis (23 horses; 43%). Odds ratios (measure of association) were calculated to determine the association of echinocytosis with specific hematologic and biochemical abnormalities. When evaluated in a multivariate model, low serum sodium concentration (< 136 mEq/L) was the only variable significantly associa...
Gomez-Perretta C, Armas-Portela R, Stockert JC, Tato A, Ferrer JM.The acidophilic reaction of eosinophil leucocyte granules from human, pig and horse blood smears was investigated by using May-Grünwald-Giemsa staining after previous treatment with EDTA and sodium citrate solutions. The same peak at 530 nm, but absorption values considerably higher than those of controls, were found in eosinophil granules after application of chelating agents, indicating that removal of metal cations could unmask basic groups in these structures.
Lees P, Tavernor WD.1. In horses anaesthetized with halothane the intravenous administration of suxamethonium chloride, at a dose level of 0.2 mg/kg, produced a short-lived period of hypoventilation, which was associated with increases in arterial blood PCO(2) levels and in plasma concentrations of bicarbonate, sodium and potassium ions, and reductions in arterial blood pH and PO(2) values.2. The respiratory depressant action of suxamethonium chloride 0.2 mg/kg was accompanied by increases in blood pressure and heart rate. Doses of suxamethonium chloride 0.4 mg/kg produced similar but quantitatively greater chang...
Traub-Dargatz JL, Ingram JT, Stashak TS, Kiper ML, Tarr S, Child G, MacAllister CG.Four Quarter Horse foals ranging in age from 6 days to 2 months were determined to have upper airway stridor secondary to polymyopathy suspected to be hyperkalemic periodic paralysis. Electromyography revealed spontaneous muscle activity in all muscles examined. Electromyographic findings were similar in the dams of 3 foals (No. 1, 3 and 4). Hyperkalemia was found in foals 1 and 4. Endoscopically, the upper airway stridor in foals 1 and 3 was confirmed to be attributable to laryngeal and pharyngeal collapse or spasm. Foals 1, 2, and 3 were treated with acetazolamide. Foal 4 was not treated, at...
Jarvis SM, Harris RC.The inward transport of two purines, adenosine and hypoxanthine, at 37 degrees C by horse erythrocytes was compared. No mediated transport of adenosine was detected in horse erythrocytes, nor was saturable, high-affinity binding of the potent facilitated-diffusion inhibitor nitrobenzylthioinosine demonstrable in horse erythrocyte membranes. In contrast, erythrocytes from most horses possessed a saturable sodium-dependent hypoxanthine transporter (apparent K(m), 100 +/- 28 microM; Vmax, 0.20 +/- 0.08 mmol (l cells)-1 h-1; means +/- S.E.M., n = 5). Guanine inhibited hypoxanthine influx (apparent...
Alexander F.1. The effect on plasma, urinary and faecal electrolytes of frusemide and hydrochlorthiazide was measured in ponies, mean weight 180 kg. 2. The rapid loss in urine of large quantities of sodium had only a small effect on plasma sodium concentration. 3. Faecal sodium excretion was increased substantially after the administration of frusemide. 4. Frusemide increased faecal potassium during the 48 h following administration and faecal water in the 24/48 h period. It also produced a hypopotassaemia. 5. Hydrochlorthiazide increased faecal chloride during the 24 h after administration. 6. Frusemide ...
Colahan PT, Bailey JE, Johnson M, Rice BL, Chou CC, Cheeks JP, Jones GL, Yang M.Following the regimen used to treat equine protozoal myeloencephalitis, sulfadiazine (20 mg/kg) and pyrimethamine (1mg/kg) were administered orally once daily to 12 physically conditioned Thoroughbred horses for 4 consecutive days. The horses were randomly assigned to two test groups in a crossover design, with each horse serving as its own control. A stepwise exercise stress test was conducted to exhaustion. No effect on athletic performance was observed, and only marginal effects were noted in some hematologic and serochemical measurements, including decreased total white blood cell counts, ...
Tschudi PR.The purpose of this study was to compare the results of horse blood examinations on a portable blood analysis system, i-STAT SDI, with conventional laboratory equipment and to verify the accuracy and precision. The precision within run was high and the coefficients of variation ranged from 0 to 3.85%. The comparative analysis of patient samples with routine methods showed a very strong positive correlation with correlation coefficients above 0.96 for blood gases, pH, glucose, urea, hemoglobin, hematocrit, sodium and potassium, with the exception of chloride where it was 0.867. The i-STAT syste...
Freeman DE, Donawick WJ.Mucosa obtained from the cecum of healthy horses and incubated in vitro with 0.1 mM cycloleucine could accumulate this amino acid against an apparent concentration gradient after 60 and 120 minutes. Accumulation by the serosal (antiluminal) surface of the tissue was 3 times greater than accumulation by the mucosal (luminal) surface after 120 minutes (P less than 0.001). Cycloleucine accumulation was significantly reduced by Na deprivation after 60 minutes (P less than 0.05) and 120 minutes (P less than 0.01) and by anoxic conditions after 120 minutes (P less than 0.05). Transmucosal flux from ...
Ziemer EL, Parker HR, Carlson GP, Smith BP.Two horses were admitted separately for evaluation and treatment of profound hyperchloremic metabolic acidosis without azotemia. One, an 11-year-old Quarter Horse mare, had been depressed and ataxic for 2 days. The other, a 2-year-old Quarter Horse colt, had a 6-week history of depression, anorexia, and weight loss. Both horses responded to fluid and electrolyte therapy, but required daily oral administration of sodium bicarbonate for maintenance. In each case, the diagnosis was renal tubular acidosis.
Robb EJ, Kronfeld DS.A 3-year-old mare repeatedly had clinical signs of rhabdomyolysis on mild exertion. Serum creatine kinase and aspartate transaminase activities were high at rest. Responses to dietary sodium bicarbonate were tested through 7 alternating periods of supplementation of a basal ration of timothy hay and oats. Physical signs; venous blood pH and gases; blood glucose and lactate; serum electrolytes, enzymes, and creatinine; and urine pH were monitored before and after exercise. Dietary sodium bicarbonate raised resting venous blood pH and bicarbonate slightly and significantly increased urine pH fro...
Frost AB, Larsen F, Ostergaard J, Larsen SW, Lindegaard C, Hansen HR, Larsen C.Development of suitable in vitro release models for formulation development as well as quality control purposes has to be initiated in the early design phase of injectable depots. Optimally, construction of an in vitro release model may lead to the establishment of in vitro in vivo correlations. By using a model compound (sodium diatrizoate, DTZ), the purpose of this study was to investigate the possibility of establishing in vitro in vivo relations between the DTZ disappearance profile obtained from the donor compartment of the rotating dialysis cell model and the joint disappearance profile ...
Muir WW, Kohn CW, Sams R.The effects of IV administered furosemide upon plasma volume (PV) and extracellular fluid volume were determined in horses at rest and after exercise. Serum sodium, potassium, chloride, and osmolality determinations were made. Furosemide caused a significant (P less than 0.05) decrease in PV and serum potassium concentrations in resting horses only. Furosemide's effects upon PV and electrolytes were evident longer than its hemodynamic effects.
Datt SC, Usenik EA.Physical signs and blood changes were studied in horses with artificially produced obstructions of the duodenum and the small colon and simulated volvulus of the ileum. Horses with obstruction of the duodenum had the most violent physical signs and the shortest survival time. Blood changes were an initial rise in pH followed by acidosis, hyperkalemia and a decrease in HCO3 minus, Na+ and C1 minus. Obstruction of the small colon resulted in mild physical signs. The blood parameters recorded were normal. Simulated volvulus resulted in continuous colic. Blood changes were acidosis and hyperkalemi...
Fielding CL, Magdesian KG, Elliott DA, Craigmill AL, Wilson WD, Carlson GP.The purpose of this study was to describe the pharmacokinetics of bromide in horses and to evaluate the corrected bromide space as an indicator of extracellular fluid volume (ECFV) in horses after the administration of a single dose of bromide by intravenous infusion. Sodium bromide (30 mg/kg of body weight, IV) was administered to 6 clinically healthy mares over a period of 3 minutes. Blood samples were collected before infusion and at intervals between 0.5 hours and 53 days after infusion. Mean elimination half-life (harmonic mean) was 126 hours (5.2 days), clearance was 1.4 +/- 0.09 mL/(kg ...
Rumbaugh GE, Carlson GP, Harrold D.Clinicopathologic effects of rapid intravenous infusion of 3 L of 5% dextrose in water containing 150 g of sodium bicarbonate were evaluated in 8 clinically normal horses. A highly significant metabolic alkalosis was produced in all the horses. This response was maximal at the end of the 20-minute infusion but persisted for as long as 8 hours. Packed cell volume, total plasma proteins, plasma potassium, and plasma chloride concentration decreased significantly after infusion, while plasma sodium concentration increased significantly. The clinical and clinicopathological responses of the horses...
Koterba A, Carlson GP.In examination of the acid-base and electrolyte status of 7 horses with acute exertional rhabdomyolysis, the most consistent abnormality was hypochloremia. Metabolic acidosis was not evident in any of the horses. Therefore, the use of sodium bicarbonate in treatment of such disorders may not be indicated in all cases.
Contreras A, Martínez R, Devés R, Marusic ET.Marked differences in the activities of three monovalent cation transport systems in horse versus human erythrocytes are reported. Whereas horse erythrocytes exhibit a 6-fold higher sodium-lithium countertransport, the unidirectional flux of potassium through the sodium pump is 3-4 times slower and the sodium-potassium cotransport system cannot be detected. In spite of this, horse and human cells are able to maintain similar Na+ and K+ gradients.
Crews LJ, Waelchli RO, Huang CX, Canny MJ, McCully ME, Betteridge KJ.To investigate how equine conceptuses expand rapidly despite the hypo-osmolality of their yolk sac fluid, 18 conceptuses, aged 8-12 days and 0.8-10.0 mm in diameter, were examined by cryoscanning electron microscopy and energy dispersive X-ray microanalysis to determine the distribution of Na, Cl and K in their fluids. No osmotic gradient was found between central and peripheral yolk sac fluid. In conceptuses > or = 6 mm in diameter, the concentrations of both Na and K in the subtrophectodermal compartments were higher than those determined previously in uterine fluid, supporting the concep...
Taylor EA, Beard WL, Douthit T, Pohlman L.Caecal acidosis is a central event in the metabolic cascade that occurs following grain overload. Buffering the caecal acidosis by enterally administered sodium bicarbonate (NaHCO3 ) may be beneficial to affected horses. Objective: To determine the effect and duration of enterally administered NaHCO3 on caecal pH in healthy horses. Methods: Experimental study using horses with caecal cannulas. Methods: Nine horses had been previously fitted with a caecal cannula. Six horses received 1.0 g/kg bwt NaHCO3 and 3 control horses were given 3 l of water via nasogastric tube. Clinical parameters, ...
Schott HC, Hinchcliff KW.A number of feeding and management practices, dietary electrolyte supplements, and medications may affect fluid and electrolyte status in resting and exercising horses. The contents of the gastrointestinal tract of the equine athlete, unlike its human counterpart, are responsible for more than 10% of body weight. Although ingesta traditionally has been considered dead weight for the sprinting horse, it is a valuable reservoir of fluid and electrolytes that may be used during endurance exercise. Numerous strategies for hyperhydration of the equine athlete and for replacement of fluid and electr...
Hyyppä S, Saastamoinen M, Pösö AR.Nine adult riding horses performed on a treadmill a competition exercise test (CET) and 24 h later a standardised exercise test (SET) at mean temperature 28 degrees C and relative humidity 58%. Each horse performed the tests 5 times at 2 week intervals. The horses were given isotonic glucose-electrolyte solution via a nasogastric tube 30 min after the CET, except after the last trial when water was given. Blood lactate, plasma concentration of aldosterone, arginine vasopressin, protein, sodium, potassium, chloride, magnesium and calcium were measured. Heart rate at blood lactate concentration ...
van der Kolk JH.A 2-year-old Friesian mare was examined because she had been sluggish for a few weeks. Blood biochemistry showed that concentrations of creatinine (136 mumol.L-1) and urea nitrogen (6.1 mmol.L-1) in plasma were within their normal limits. Severe metabolic acidosis was apparent; the venous pH was 7.154 and the bicarbonate concentration was 13 mmol.L-1. The base excess amounted to -15.3 mmol.L-1 and the venous pCO2 measured 5.1 kPa. Plasma sodium was normal (135 mmol.L-1) and plasma chloride (113 mmol.L-1) was slightly elevated, but there was a hypokalaemia (2.9 mmol.L-1). The urine had a specif...
Waelchli RO, Betteridge KJ.Horse conceptuses collected between Day 11 and Day 18 of pregnancy float in isotonic media. To investigate this phenomenon, blastocyst fluids from 30 conceptuses from 13 mares were analysed for osmolality and for concentrations of Na+, Cl-, K+, glucose, urea and creatinine. In conceptuses from Group A, samples from Day 11 to Day 16 yielded the following results (mean +/- s.e.m.): osmolality, 121.4 +/- 1.5 mOsm kg-1; Na+, 11.0 +/- 2.2 mM; Cl-, 29.3 +/- 2.5 mM; K+, 26.2 +/- 2.6 mM; glucose, 0.6 +/- 0.1 mM; urea, 6.0 +/- 0.6 mM; creatinine, 9.6 +/- 1.1 microM. Between Day 16 and Day 25, the osmol...
Cohen ND, Roussel AJ, Lumsden JH, Cohen AC, Grift E, Lewis C.Alterations of acid-base status, and fluid and electrolyte balance subsequent to exercise in Thoroughbred racehorses in North America have not been well-characterized. Des-cribed here are the results of an observational study conducted to characterize changes in fluid and electrolytes following strenuous exercise of 16 Thoroughbreds under routine training conditions. Changes following strenuous exercise were determined for the following variables: serum concentrations of sodium (Na), potassium (K), chloride (Cl) and protein; pH of blood; osmolality of plasma and urine; body weight; and, fracti...
Wijnberg ID, van der Kolk JH, Franssen H, Breukink HJ.To determine whether electromyographic abnormalities are evident in skeletal muscles in horses with induced hypocalcemia and hypomagnesemia. Methods: 7 healthy adult Dutch Warmblood horses. Methods: Electromyographic examination was performed in the lateral vastus, triceps, and subclavian muscles before and after IV infusion of EDTA. An initial dose (mean +/- SD, 564+/-48 ml) of a 10% solution of sodium EDTA was administered IV during a period of 21+/-73 minutes to establish a blood concentration of ionized calcium of approximately 0.5 mmol/L. Average rate of EDTA infusion to maintain ionized ...