Electrolytes are minerals that carry an electric charge and are essential for various physiological functions in horses. These minerals include sodium, potassium, chloride, calcium, and magnesium, among others. Electrolytes are involved in maintaining fluid balance, nerve function, muscle contraction, and acid-base balance in equine bodies. Imbalances or deficiencies in electrolytes can occur due to factors such as exercise, diet, or illness, affecting a horse's performance and health. This page compiles peer-reviewed research studies and scholarly articles that explore the role, regulation, and impact of electrolytes on equine physiology and performance.
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...
McCutcheon LJ, Geor RJ.In the horse, sweat is produced by apocrine glands which are present over most haired and nonhaired skin. Although sweat secretion is initiated under a number of circumstances, the central drive for sweating in response to a thermal stimulus is the primary mechanism for its production. Sweating is an essential and primary mechanism for heat dissipation during exercise or exposure to hot ambient conditions. The rate of sweat production will reflect the interaction of numerous factors, including exercise intensity, ambient conditions, state of hydration, and the training or heat acclimation stat...
Flaminio MJ, Rush BR.In horses, fluid losses of 10L to 15L per hour can occur during endurance exercise under hot environmental conditions. The horse's sweat is hypertonic with respect to plasma, and large amounts of sodium, chloride and potassium are lost during prolonged exercise. Horses that reach exhaustive syndrome often show pronounced increases in plasma protein concentration. This could be an indication of failure of the compensatory fluid shift from the intracellular compartment caused by severe dehydration. Thorough physical examination by the ride veterinarian allows early recognition of dehydration and...
White SL.Horses competing in 3-day, combined-training events develop a metabolic acidosis that is partially compensated for by a respiratory alkalosis immediately after phases B and D. By the end of phase C and 30 minutes to 2 hours after phase D, the acidosis is resolved by the oxidation of lactate, and a metabolic alkalosis prevails. A reduction in TBW and cation content occurs, which often is not replenished 12 to 24 hours after the event, even though the serum or plasma concentration of various constituents may be within normal limits. Hypochloremia and hypocalcemia, however, may persist 12 or more...
Hyyppä S, Pösö AR.During both high-intensity and short-distance exercise, the high rate of expended energy is met by anaerobic oxidation of glucose to lactic acid; this is the main cause of metabolic acidosis observed during racing. In addition, plasma volume decreases because water moves from the vasculature to the intracellular and interstitial spaces at the onset of intense exercise. These fluid shifts, together with active ion-exchange between blood and tissue, cause marked changes in electrolyte concentrations. This article reviews the mechanisms of acid-base disturbances, fluid shifts, and electrolyte cha...
Johnson PJ.This article presents a brief overview of the physiology of homeostasis in the horse and discusses the units of measurement by which dissolved electrolytes are assessed. Differences in electrolyte composition between compartments of the body and the manner in which water is exchanged between them are reviewed. The mechanisms by which alterations in osmolality and effective circulating volume are detected and the physiological responses to those alterations are presented.
McKeever KH.Exercise places large demands on the equine cardiovascular system which are further complicated by environmental factors. In many respects, performance is limited by fluid and electrolyte stores and the ability to maintain cardiovascular and thermoregulatory stability in the face of severe sweat losses. Studies in the exercising horse have been primarily descriptive or associative, with only a limited number seeking to identify physiologic mechanisms associated with the control of fluid and electrolyte balance. More mechanistic studies are needed to fully understand the integration of the card...
Foreman JH.Exhaustion occurs in most equestrian sports, but it is more frequent in events that require sustained endurance work such as endurance racing, three-day eventing, trial riding, and hunting. Exhaustion is also more likely when an unfit, unacclimatized, or unsound horse is exercised. Mechanisms that contribute to exhaustion include heat retention, fluid and electrolyte loss, acid-base imbalance, and intramuscular glycogen depletion. Clinical signs include elevated temperature, pulse, and respiratory rate; depression; anorexia; unwillingness to continue to exercise; dehydration; weakness; stiffne...
Friend TH, Martin MT, Householder DD, Bushong DM.To characterize progressive patterns of dehydration, stress responses, and water consumption in horses transported long distances in hot weather and to evaluate various measurements in detecting dehydration and stress in transported horses. Methods: Prospective study. Methods: 30 mature, healthy horses. Methods: The following 4 treatment groups were studied: horses that were penned and offered water every 5 hours (n = 5), horses that were penned and not offered water (5), horses that were transported in a truck and offered water every 5 hours (10), and horses that were transported and not offe...
Sosa León LA, Hodgson DR, Rose RJ.We examined the gastric emptying (GE) of oral rehydration solutions (ORS) at rest and after exercise in four Standardbred horses. In one study isotonic, cold isotonic (5 degrees C), isotonic containing glucose and hypertonic fluid were tested at rest. In another study, isotonic fluid was given following a bout of treadmill exercise at 70 per cent VO2 max until exhaustion or at rest. In both studies, a single dose of 8 litres was given via nasogastric tube. GE and electrolyte concentrations (Na+, K+ and Cl-) of the stomach content were measured at 15 minutes intervals for one hour. In both stud...
Dabareiner RM, White NA.The cecum is an important site of water and electrolyte absorption, as well as microbial digestion of soluble and insoluble carbohydrates. These functions of the cecum and ascending colon require that ingesta be mixed constantly and retained long enough to complete the digestion of cellulose. Parasites, changes in regional blood flow, diet, and various pharmacologic agents are associated with alterations in normal cecal motility patterns.
Schott HC, McGlade KS, Molander HA, Leroux AJ, Hines MT.To investigate effects of prolonged exercise on fluid and electrolyte losses in horses competing in 50- and 100-mile endurance competitions, with emphasis on recovery. Methods: Changes in body weight (BW); PCV; serum osmolality; plasma total protein, lactate, aldosterone, and serum electrolyte concentrations; and exchangeable cation content were measured in 12 and 7 horses before and after and before, during, and after successful completion of 50- and 100-mile endurance rides, respectively. Methods: BW was measured by use of a portable load bar scale, and blood samples were collected during th...
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 ...
McCutcheon LJ, Geor RJ.The objectives of this study were to: 1) determine incremental and total sweat fluid and ion losses during and following (a) exercise training and (b) a treadmill Speed and Endurance exercise test (SEET) which simulated running speeds and distances required for each phase of an Olympic level (CCI****) 3-day-event in cool and hot ambient conditions and 2) determine the requirement for ion supplementation based on the calculated ion losses associated with these activities. Six exercise-trained Thoroughbred horses completed 2 weeks of exercise training in each of 2 ambient conditions: cool, dry (...
Nyman S, Jansson A, Dahlborn K, Lindholm A.To avoid dehydration and a decrease in performance capacity in horses, fluid and electrolyte losses need to be compensated for during long distance rides as well as on other occasions when sweat losses are high during exercise. Thirteen endurance-trained horses, age 5-14 years, were used to compare 3 strategies of voluntary rehydration during prolonged exercise, offering 1) water, 2) water after administering salt paste (3 x 30 g of NaCl) per os and 3) 0.9% saline. The ride covered 62 km and consisted of 3 rounds, of 20, 22 and 20 km, respectively. During the first 20 km, no fluid was offered ...
Foreman JH, Grubb TL, Benson GJ, Frey LP, Foglia RA, Griffin RL.This study was designed to characterise the acid-base and electrolyte effects of shortening the distance required during steeplechase (Phase B) in the face of hot and humid weather conditions during a treadmill-simulated Speed and Endurance test. Eight conditioned Thoroughbred horses underwent 3 randomised permutations of a standardised exercise test on a high speed treadmill. Each test consisted of trotting at 3.7 m/s for 10 min (Phase A); galloping at 11 m/s (Phase B) for 4 (cool laboratory conditions), 3 (hot and humid), or 2 (hot and humid) min; trotting at 3.7 m/s for 30 min (Phase C); an...
Saville WJ, Hinchcliff KW, Moore BR, Kohn CW, Reed SM, Mitten LA, Rivas LJ.The clinical and clinicopathologic characteristics of fatal necrotizing enterocolitis were examined in 16 horses (age 4 months to 12 years). At initial presentation, 8 of 16 horses were pyrexic (median temperature, 38.4 degrees C; range, 33.8 to 40.6 degrees C); all 16 were tachycardic (median heart rate, 93 bpm, range, 66 to 138 bpm); 13 of 16 were tachypneic (median heart rate, 36 bpm, range, 16 to 80 bpm), dehydrated, and had discolored mucous membranes. All horses that were pyrexic were also tachycardic and tachypneic. PCV was high (> 45%) in 14 horses. Six horses were leukopenic (< 5,000 ...
The Journal of physiologyJune 15, 1996
Volume 493 ( Pt 3), Issue Pt 3 885-894 doi: 10.1113/jphysiol.1996.sp021431
Ko WH, Chan HC, Chew SB, Wong PY.1. The ionic mechanism involved in Ca(2+)-stimulated electrolyte transport in cultured equine sweat gland epithelial cells was studied using the short-circuit current (ISC) technique. 2. Microscopy revealed that the cultured cells grown on Millipore filters formed polarized monolayers with tight junctions. Monolayers exhibited a mean transepithelial resistance of 333.9 +/- 40.4 omega cm2. 3. Ca(2+)-mobilizing agents, A23187 (1 microM) or thapsigargin (0.01-1 microM), stimulated ISC while forskolin exerted little effect on the ISC. 4. Replacement of external Cl- by gluconate significantly reduc...
Weiss DJ, Geor RJ, Burger K.To determine whether furosemide treatment altered the blood flow properties and serum and RBC electrolyte concentrations of Thoroughbreds during submaximal treadmill exercise. Methods: Thoroughbreds were subjected to submaximal treadmill exercise with and without treatment with furosemide (1 mg/kg of body weight, IV). Methods: 5 healthy Throughbreds that had raced within the past year and had no history of exercise-induced pulmonary hemorrhage. Methods: Venous blood samples were obtained before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise, and hemorheologic and ...
Bickhardt K, Deegen E, Espelage W.Investigations of renal function have been done on the basis of renal clearance (Clr) and excretion (E) of endogenous creatinine in healthy horses of different body weight (23 female, 7 male). Creatinine was measured by enzymatic PAP-method. Creatinine-E of female horses was poor positively correlated with body weight. The creatinine-Clr was highly correlated with the inulin-Clr (r = 0,896, p < 0,001). The excretion of creatinine was 35% higher than the filtration of creatinine, determined by inulin-Clr. That demonstrate a tubular net secretion of 26% of the total creatinine excretion. However...
Johnson PJ.Laboratory electrolyte and acid-base analyses are important for the characterization and assessment of the severity of disorders of fluid balance, and they enable the veterinarian to institute appropriate corrective therapeutic interventions. Abnormalities of electrolytes or acid-base rarely define the diagnosis, but certain diseases are characterized by predictable trends in these parameters. Important clinical situations in which assessment of electrolyte and acid-base status should be regarded as important to the equine practitioner include diarrhea, severe colic, peritonitis, pleuritis, dy...
Harris PA, Marlin DJ, Scott CM, Harris RC, Mills PC, Michell AR, Orme CE, Roberts CA, Schroter RC, Marr CM.Four horses (H, J, N and M) undertook a simulated competition exercise test (CET), designed to simulate physiological and metabolic stresses of the Speed and Endurance (S & E) test of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD] 2 sessions); 30 degrees C/40% RH (hot, dry [HD]) and 30 degrees C/80% RH (hot, humid [HH]) (Marlin et al. 1995a). Venous blood samples for electrolyte and total protein (TP) determinations were collected from indwelling catheters at predetermined time points throughout each CET and initial 30 min...
Art T, Votion D, Lekeux P.The purpose of this study was 1) to measure and compare some physiological parameters in horses during a standardised treadmill exercise performed either in temperate atmospheric conditions (TC) (ambient temperature: 15 degrees C; relative humidity: 55%), or in hot and humid conditions (HHC) (ambient temperature: 30 degrees C; relative humidity: 75%) and 2) to follow the recovery of the same horses during 1 h after both tests. Five healthy fit Standardbred horses were investigated twice at 8 days interval, in TC and in HHC. Some measurements were made during a standardised treadmill exercise t...
Hinchcliff KW, Kohn CW, Geor R, McCutcheon LJ, Foreman J, Andrews FM, Allen AK, White SL, Williamson LH, Maykuth PL.We examined the effects of participation in each of 3 modifications of Day 2 of a 3-day-event on blood and serum variables indicative of hydration, acid:base status and electrolyte homeostasis of horses. Three groups of horses - 8 European (E) horses and 2 groups each of 9 North American horses performed identical Days 1 (dressage) and 3 (stadium jumping) of a 3-day-event. E horses and one group of the North American horses (TD) performed modifications of Day 2 of a 1 Star 3-day-event and the other group of North American horses (HT) performed a Horse Trial on Day 2. Jugular venous blood was c...
Sosa León LA, Davie AJ, Hodgson DR, Rose RJ.Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in e...
Jansson A, Nyman S, Morgan K, Palmgren-Karlsson C, Lindholm A, Dahlborn K.In this study 4 Standardbred geldings (age 3-8 years, weight 431-531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed. Phase I consisted of 23.5 min of mainly submaximal exercise, Phase 2 of 2 h of box rest and Phase 3 of 26 min of exercise including an intensive trot over 2600 m at 90% of VO2max. The ET was repeated 3 times: the first at 20 degrees C (30-40% RH), the second at 35 degrees C (30-40% RH) and the third at 35 degrees C (30-40% RH) after a nasogastric...
Maughan RJ, Lindinger MI.This review provides an overview of the challenges that face man and horses when exercising in the heat. Some of the strategies that are used and are being developed for human athletes exercising in the heat are reviewed. There are many similarities between human and equine physiological responses to exercise in the heat; and equine exercise science may gain some useful insights from the training, fluid replacement and heat acclimatisation strategies used by human athletes. There are, however, some important differences that impact on the ability of horses to thermoregulate and to regulate flu...
Andrews FM, White SL, Williamson LH, Maykuth PL, Geiser DR, Green EM, Ralston SL, Mannsman RA.Thirty-four horses competing in the Endurance Test of a 3-day-event were divided into 3 groups: horses in Group 1 (n = 15) competing in a 3.5 min steeplechase phase; horses in Group 2 (n = 13) in a 3 min steeplechase phase (Phase B) and horses in Group 3 (n = 6) in a 2.5 min steeplechase phase. The shortening of Phase B was associated with a lengthening of Phase C so that the total distance of the event for all horses was 14,940 m. Bodyweight (BW) was measured and total body water (TBW) and water loss estimated. Blood samples were collected from the horses prior to the Endurance Test, at the e...
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)...
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 ...
Agne GF, Jung SW, Wooldridge AA, Duran SH, Ravis W, Toribio R.Diuretic treatment is the mainstay for management of congestive heart failure in horses, and its use has been restricted to injectable medications because no currently data supports the use of PO administered loop diuretics. Objective: To determine the pharmacokinetic and pharmacodynamic properties of PO administered torsemide and, determine if PO administered torsemide, could be used as an alternative to injectable diuretics in the horse. Methods: Six healthy adult mares. Methods: A 2-phase, prospective study, that consisted of pharmacokinetic profiling of a single dose (6 mg/kg PO) and pharm...
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...
Art T, Votion D, Lekeux P.The purpose of this study was 1) to measure and compare some physiological parameters in horses during a standardised treadmill exercise performed either in temperate atmospheric conditions (TC) (ambient temperature: 15 degrees C; relative humidity: 55%), or in hot and humid conditions (HHC) (ambient temperature: 30 degrees C; relative humidity: 75%) and 2) to follow the recovery of the same horses during 1 h after both tests. Five healthy fit Standardbred horses were investigated twice at 8 days interval, in TC and in HHC. Some measurements were made during a standardised treadmill exercise t...
Gomez DE, Buczinski S, Darby S, Palmisano M, Beatty SSK, Mackay RJ.Use of different analyzers to measure electrolytes in the same horse can lead to different interpretation of acid-base balance when using the simplified strong ion difference (sSID) approach. Objective: Investigate the level of agreement between 2 analyzers in determining electrolytes concentrations, sSID variables, and acid-base disorders in sick horses. Methods: One hundred twenty-four hospitalized horses. Methods: Retrospective study using paired samples. Electrolytes were measured using a Beckman Coulter AU480 Chemistry analyzer (PBMA) and a Nova Biomedical Stat Profile (WBGA), respectivel...
Magalhaes HB, Canuto LEF, Canisso IF.The objectives of this study were to determine (i) the usefulness of serial assessment of mammary gland electrolytes concentrations and correspondent pH to detect impending parturition in jennies; and (ii2) the associations between mammary gland secretions, and gestation length, foal sex, maternal, placental, and foal birth weights. Multiparous jennies (n = 37) were monitored daily from 350 to 355 days of gestation until parturition. The pH of mammary gland secretions was assessed daily with a hand-held device. Aliquots of mammary secretions were frozen daily and then retrospectively assesse...
Gómez-Díez M, Muñoz A, Caballero JM, Riber C, Castejón F, Serrano-Rodríguez JM.Pharmacokinetic and pharmacodynamic of IV enalapril at 0.50 mg/kg, PO placebo and PO enalapril at three different doses (0.50, 1.00 and 2.00 mg/kg) were analyzed in 7 healthy horses. Serum concentrations of enalapril and enalaprilat were determined for pharmacokinetic analysis. Angiotensin-converting enzyme (ACE) activity, serum ureic nitrogen (SUN), creatinine and electrolytes were measured, and blood pressure was monitored for pharmacodynamic analysis. The elimination half-lives of enalapril and enalaprilat were 0.67 and 2.76 h respectively after IV enalapril. Enalapril concentrations ...
Huskamp B.Gastroduodenojejunitis is a catarrhal inflammation of the stomach and proximal portion of the small intestine. Secondary overloading of the stomach occurs so that affected horses rapidly enter a state of hypovolaemic shock which is further complicated by the presence of toxins. The condition can occur in a mild or severe form. In mild cases, conservative treatment comprising intravenous electrolyte therapy and repeated gastric decompression is indicated and is usually successful. In severe cases surgical treatment creating duodenocaecal anastomosis has given good results. This should be carrie...
Tofé E, Muñoz A, Castejón F, Trigo P, Castejón-Riber C, Gómez-Díez M, Riber C.The influence of hydration prior to exercise on hormonal response to exercise was investigated in horses, divided into two groups, control (n=11) and dehydrated (n=53). They were also classified according to their body weight in A (≈ 350 kg), B (351-450 kg) and C (≈ 451 kg). Horses covered 60 m on a track pulling a carriage loaded with 2, 2.25 and 2.5 times their body weight, for A, B and C. Blood samples were taken at rest, after exercise and during recovery. Electrolytes, albumin, renin, angiotensin and aldosterone concentrations were measured. Dehydrated and control horses had higher al...
Ohta M, Kurimoto S, Tokushige H, Kuroda T, Ishikawa Y.To determine hemodynamic effects of hydroxyethyl starch (HES) infusion during anesthesia in horses, incremental doses of 6% HES were administered to 6 healthy Thoroughbred horses. Anesthesia was induced with xylazine, guaifenesin and thiopental and maintained with sevoflurane at 2.8% of end-tidal concentration in all horses. The horses were positioned in right lateral recumbency and administered 3 intravenous dose of 6% HES (5 ml/kg) over 15 min with 15-min intervals in addition to constant infusion of lactated Ringer's solution at 10 ml/kg/hr. Hemodynamic parameters were measured before and e...
Schmall LM, Muir WW, Robertson JT.The effects of treatment with small volume hypertonic (2400 mOsm/litre) and isotonic (300 mOsm/litre) saline on serum electrolyte and biochemical concentrations, haemograms and blood gases were evaluated in 12 horses using a haemorrhagic shock model. Intravascular catheters were placed surgically for sample collection prior to anaesthesia. Controlled haemorrhage was initiated and continued until mean systemic pressure reached 50 to 60 mmHg. Hypertonic or isotonic saline (2 litres) was administered by intravenous infusion and data collected for 2 h. Following haemorrhage, packed cell volume (PC...
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...
Fielding CL, Magdesian KG, Carlson GP, Rhodes DM, Ruby RE.To apply the principle of sodium dilution to calculate the changes in the extracellular fluid (ECF) volume (ECFV) and intracellular fluid volume (ICFV) that occur during dehydration and rehydration in horses. Methods: 8 healthy horses of various breeds. Methods: Horses were dehydrated over 4 hours by withholding water and administering furosemide. Saline (0.9% NaCl) solution was administered IV during the next 2 hours (20 mL/kg/h; total 40 mL/kg). Horses were monitored for an additional hour following IV fluid administration. Initial ECFV was determined by use of multifrequency bioelectrical i...
Deldar A, Fregin FG, Bloom JC, Davanipour Z.The effects of strenuous exercise on serum electrolytes, blood metabolites, and serum enzymes were studied in a group of 13 horses participating in a 50-mile endurance ride. Blood samples were collected before, during, and at the end of the ride, as well as 1 hour and 16 hours after the completion of the ride. There were significant changes in these values when preride values were compared with those of samples taken at different sample-collection periods. Significant (P less than 0.001) decreases were observed in serum concentrations of chloride, potassium, and calcium. A significant increase...
Bailey J, Colahan P, Kubilis P, Pablo L.This study was designed to test the hypothesis that a specific beta 2 adrenergic receptor agonist, albuterol sulphate, when delivered by metered-dose inhaler (MDI) would affect the performance of Thoroughbred horses during incremental exercise testing. Six conditioned Thoroughbred horses were randomly assigned to one of 2 treatment groups: Group 1 horses received placebo and Group 2 received albuterol. Each horse received both treatments in a crossover design with a 3 week interval between trials. Horses inspired albuterol (900 micrograms) or placebo over a 5 min period followed by an incremen...
McKeever KH, Scali R, Geiser S, Kearns CF.The purpose of the present study was to determine whether the training-induced hypervolaemic response seen in the horse is associated with aldosterone-mediated renal mechanisms affecting sodium conservation during the first days of training. Five healthy, Standardbred mares (weight 450-500 kg, age 4-8 years) that were unfit, but accustomed to running on the treadmill, were used to test the hypothesis that repeated submaximal exercise would alter plasma aldosterone (ALDO) concentration and renal excretion of electrolytes in horses within the first 3 days of training. The experiment consisted of...
Waterman A.Disturbances of fluid and electrolyte balance may occur in the horse as a consequence of many disease processes. Disorders may be classified into 3 main categories, primary water loss, mixed water and electrolyte depletion and acid base disturbances. This paper reviews the changes which occur with each type of disorder and discusses methods of diagnosis and assessment of such imbalances. The principles of treatment are described and the management of fluid replacement therapy in 3 of the disorders, mainly acute intestinal obstruction, inability to drink and diarrohea is discussed.
Foreman JH, Grubb TL, Benson GJ, Frey LP, Foglia RA, Griffin RL.This study was designed to characterise the acid-base and electrolyte effects of shortening the distance required during steeplechase (Phase B) in the face of hot and humid weather conditions during a treadmill-simulated Speed and Endurance test. Eight conditioned Thoroughbred horses underwent 3 randomised permutations of a standardised exercise test on a high speed treadmill. Each test consisted of trotting at 3.7 m/s for 10 min (Phase A); galloping at 11 m/s (Phase B) for 4 (cool laboratory conditions), 3 (hot and humid), or 2 (hot and humid) min; trotting at 3.7 m/s for 30 min (Phase C); an...
van der Kolk JH, de Groot J.Serological surveys showed that equine monocytic ehrlichiosis (EME) occurs in the USA, Canada and Europe. The causative agent is Rickettsia Ehrlichia risticii, isolated for the first time in 1984. The clinical features of the disease are sluggishness, anorexia, colic and fever, possibly followed by watery diarrhoea. Complications of an infection with E. risticii are laminitis and abortion. Colitis of the ascending colon may be observed at autopsy. Following a positive serological diagnosis (IgM ELISA) of EME, treatment with oxytetracycline can be initiated. It is also important to restore the ...
Eiler H, Goble D, Oliver J.The plasma concentration of hydrocortisone was determined in mares given either cosyntropin (100 IU, given IV) or corticotropin (200 IU, given IM). Plasma hydrocortisone concentrations of the mares treated with cosyntropin increased by 46%, 57% and 80% at 30, 60, and 120 minutes, respectively, when compared with base-line values; these values returned to base line at 240 minutes. In mares treated with corticotropin, mean plasma hydrocortisone concentrations increased by 42%, 143%, 101% and 155% at 30, 60, 120, and 240 minutes, respectively, when compared with base-line values. Differences in t...
Frey LP, Kline KH, Foreman JH, Lyman JT.The efficacy of using calcium carbonate as an osmolar control treatment for acid-base studies in horses receiving alkalizing compounds was evaluated. Six mares were nasogastrically intubated with isomolar quantities of sodium or calcium as sodium bicarbonate or calcium carbonate or with water during three treatment periods. Doses of the carbonic acid salts were 500 mg/kg sodium bicarbonate mixed with 4 L of distilled water (positive control) and 595 mg/kg calcium carbonate mixed with 2 L of distilled water to yield isoosmolar treatments. Four liters of distilled water served as the negative co...
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)...
Rose RJ.In this article a physiological approach to fluid therapy is discussed, commencing with examination of fluid distribution in the normal horse. The functions of individual plasma electrolyte concentrations are considered and practical causes of acid-base disturbances discussed. When fluid administration is necessary, selection of the route for fluid administration as well as the type of fluid are important considerations and these must be adjusted to the needs of the individual case. Balanced polyionic solutions appear to be most suitable for general use because normal saline can produce hypoka...
Hjortkjaer RK.In the first series of experiments enema containing a water soluble marker was given to two groups of horses fasted for 1 and 18 hours, respectively. The marker was only in 1 out of 14 experiments found orally of the pelvic flexure (Table II). Fasting seemed to facilitate the flow in oral direction. The results were discussed with the possible significance in the treatment of large intestinal impactions. In the second series the effect of enemas on water, electrolyte and acid-base status in the acute furosemide-dehydrated horse was studied. Moderate acidifying and hypokalemic effect was encoun...
Rose RJ.Many factors can influence electrolytes in the horse. With the major electrolytes (sodium and potassium), alterations in serum or plasma values do not reflect changes in total body status. However, estimates of electrolyte alterations may be made by combining assessments of body weight changes with plasma sodium values by using the formula of Edelman et al. In planning electrolyte therapy, it has to be remembered that access to green feed or hay is important in correcting any total body potassium depletion and that diets marginal in sodium may interfere with exercise capacity by limiting sweat...
Ousey JC, Dudan F, Rossdale PD.The status of the mare and foetus in relation to readiness for birth was assessed by measurement of the electrolytes sodium, potassium and calcium in mammary secretions pre-partum. Sixteen Thoroughbred mares were allowed to foal spontaneously and the ionic status of their mammary secretions was measured over three to five weeks pre-partum. From these measurements, a scoring system was developed where an ionic score of 35 points or more suggested that the mare was within 24 h of foaling. On the basis of this ionic score, 10 pony mares were induced with either oxytocin or fluprostenol and assess...
Weiss DJ, Geor RJ, Burger K.To determine whether furosemide treatment altered the blood flow properties and serum and RBC electrolyte concentrations of Thoroughbreds during submaximal treadmill exercise. Methods: Thoroughbreds were subjected to submaximal treadmill exercise with and without treatment with furosemide (1 mg/kg of body weight, IV). Methods: 5 healthy Throughbreds that had raced within the past year and had no history of exercise-induced pulmonary hemorrhage. Methods: Venous blood samples were obtained before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise, and hemorheologic and ...
Kohn CW, Strasser SL.Urine samples were obtained from 6 healthy mares. During a 2-day acclimation period, mares were kept in stalls, fed sweet feed and mixed grass hay, and allowed free access to water and trace mineral salt. The mares were crosstied in their stalls within reach of hay, salt, and water for 24 hours during which urine was obtained by constant flow via indwelling Foley catheters. Twenty-four-hour urine production was 7,649 to 11,904 ml/day (mean = 9,212 +/- 1,9285) or 14.7 to 25.1 mlĝ/day. (mean = 19.3 +/- 4.1). Urinary excretion and clearance of electrolytes and protein were determined from aliquo...
Maughan RJ, Lindinger MI.This review provides an overview of the challenges that face man and horses when exercising in the heat. Some of the strategies that are used and are being developed for human athletes exercising in the heat are reviewed. There are many similarities between human and equine physiological responses to exercise in the heat; and equine exercise science may gain some useful insights from the training, fluid replacement and heat acclimatisation strategies used by human athletes. There are, however, some important differences that impact on the ability of horses to thermoregulate and to regulate flu...
Hess TM, Kronfeld DS, Carter RA, Treiber KH, Byrd BM, Staniar WB, Smith LT, Gay LA, Harris PA.Electrolyte mixtures given to counter sweat loss usually contain abundant potassium. However, increases in plasma [K+] occur with exercise and supplementation may further increase plasma levels, potentially increasing the risk of neuromuscular hyperexcitability and development of adverse clinical sequellae. This proposition requires study. Objective: To compare effects of a K-rich electrolyte supplement (EM+K) to a K-free one (EM-K) on plasma [K+], [Ca++] and acid-base status during an endurance incremental exercise test on the treadmill. Methods: The test consisted of 3 bouts (simulating loop...
