Hydration in horses refers to the maintenance of adequate fluid balance within the body, which is essential for physiological functions, including temperature regulation, digestion, and circulation. Horses obtain water primarily through drinking and to a lesser extent from feed. Factors such as exercise, environmental conditions, and diet can influence a horse's hydration status. Monitoring hydration involves assessing parameters such as skin elasticity, mucous membrane moisture, and urine concentration. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms of fluid balance, the effects of dehydration, and strategies for maintaining optimal hydration in horses.
Smith L, Moran AW, Al-Rammahi M, Daly K, Shirazi-Beechey SP.Studies carried out in several species have demonstrated that detection of low-calorie sweeteners in the lumen of the intestine, by the sweet receptor, T1R2-T1R3, initiates a signaling pathway leading to enhanced expression and activity of intestinal Na/glucose cotransporter 1, SGLT1. This results in an increased gut capacity to absorb glucose, sodium chloride and water, the basis for oral rehydration therapy. Horses express T1R2, T1R3 and downstream signaling elements in the intestinal tissue. As such, the potential of sweetener-stimulation of T1R2-T1R3 leading to upregulation of SGLT1 allows...
Lindinger MI.Horses that sweat for prolonged periods lose considerable amounts of water and electrolytes. Maintenance of hydration and prevention of dehydration requires that water and electrolytes are replaced. Dehydration is common in equine disciplines and can be avoided, thus promoting equine wellness, improved performance and enhanced horse and rider safety. Significant dehydration occurs through exercise or transport lasting one hour or more. Oral electrolyte supplementation is an effective strategy to replace water and electrolytes lost through sweating. The stomach and small intestine serve as a re...
Waller AP, Lindinger MI.Exercise results in rapid and large extracellular to intracellular fluid shifts, as well as significant sweating losses of water and ions. It is unknown whether ions within oral electrolyte supplements are taken up by muscle (and other soft tissues) and whether oral supplementation can effectively offset sweating losses. Pre-loading with 8 L of a balanced hypotonic electrolyte supplement attenuated extracellular fluid losses, increased exercise duration and increased sweating fluid and ion losses during submaximal exercise. Supplemented electrolytes appear in skeletal muscle within 1 h after...
Akbari Shahkhosravi N, Gohari S, Komeili A, Burvill C, Davies H.Most simulation studies on equine hoof biomechanics employed linear elastic (LE) material models. However, the equine hoof wall's stress-strain relationship is nonlinear and varies with hydration level. Therefore, it is essential to investigate the accuracy of the LE model compared to more advanced material models, such as hyperelastic (HE) or viscoelastic models. The current research investigated performances of LE and three HE models (Mooney-Rivlin, Neo-Hookean, and Marlow) in describing equine hoof's mechanical behavior using finite element (FE) analysis. In the first attempt, a rectangular...
Kiely M, Warrington GD, McGoldrick A, Pugh J, Cullen S.Kiely, M, Warrington, GD, McGoldrick, A, Pugh, J, and Cullen, S. Physiological demands of professional flat and jump horse racing. J Strength Cond Res 34(8): 2173-2177, 2020-No information is currently available on the effect of race distance on the physiological demands of jockeys. This study aimed to quantify the respective demands of short and long flat and jump race distances. Twenty professional jockeys (10 flat and 10 jump) participated in the study. The subjects initially performed a graded incremental exercise test to volitional exhaustion on a treadmill to determine the peak heart rat...
Rinnovati R, Romagnoli N, Gentilini F, Lambertini C, Spadari A.Platelet-rich plasma (PRP) commonly refers to blood products which contain a higher platelet (PLT) concentration as compared to normal plasma. Autologous PRP has been shown to be safe and effective in promoting the natural processes of soft tissue healing or reconstruction in humans and horses. Variability in PLT concentration has been observed in practice between PRP preparations from different patients or from the same individual under different conditions. A change in PLT concentration could modify PRP efficacy in routine applications. The aim of this study was to test the influence of envi...
O'Reilly J, Cheng HL, Poon ET.Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the "in-race" heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. "In-race" HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (le...
Zinchenko AV, Govorova YS.Critical to the understanding the mechanism of destruction and protection during cryopreservation of biological objects is the knowledge of the conformational transitions of biopolymers experiencing low temperatures in the presence of cryoprotective agents. This information may be derived from the kinetic and thermodynamic parameters of macromolecular thermal denaturation kinetics under different environmental conditions. Objective: The study deals with the influence of cryoprotective agents (glycerol, 1.2-propanediol (1.2-PD), and dimethyl sulfoxide (DMSO)) on thermodynamic and kinetic parame...
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...
Sugimoto M, Kuwano A, Ikeda S, Kume S, Yoshihara E, Wada S.To examine the distribution of water in hoof wall specimens of horses via nuclear magnetic resonance (NMR) microscopy and determine changes in water distribution during hydration. Methods: 4 hoof wall specimens (2 obtained from the dorsum and 1 each obtained from the lateral quarter and lateral heel regions) of the stratum medium of healthy hooves of 1 horse. Methods: Equine hoof wall specimens were examined via NMR microscopy. Proton density-weighted 3-D images were acquired. Changes during water absorption were assessed on sequential images. Results: The inner zone of the stratum medium had ...
Hampson BA, de Laat MA, Mills PC, Pollitt CC.To determine the effect of various environmental conditions on the degree of hydration in hoof wall horn tissue from feral horses and investigate the effect of short-term foot soaking on moisture content in hoof wall and sole tissue in domestic horses. Methods: 40 feral horses from 3 environments (wet and boggy [n = 10], partially flooded [20], and constantly dry desert [10]) and 6 nonferal Quarter Horses. Methods: The percentage of moisture content of hoof wall samples from feral horses was measured in vitro. In a separate evaluation, the percentage of moisture content of hoof wall and sole t...
Fielding CL, Dechant JE.Colic is a common reason for elimination from equine endurance competitions and has recently been identified as the leading cause of mortality in this group of horses. Hydration and electrolyte derangements are often severe, but are probably related to endurance exercise and not necessarily the episode of colic. Better understanding of the causes of colic and the expected outcome is needed to guide treatment decisions in endurance horses. Objective: To describe the history, case details, clinical examination, laboratory, treatment and outcomes for horses presenting to equine referral centres f...
Nógrádi N, Tóth B, Macgillivray KC.Factors associated with the outcome of peritonitis in horses are seldom described. The objectives of this study were to determine the common clinical signs and clinicopathologic findings and to reveal prognostic factors associated with the outcome of peritonitis in equine patients. Data were examined in a retrospective manner in 55 horses diagnosed with and treated for peritonitis. The most common clinical and clinicopathologic findings were tachycardia (94%), increased amount of peritoneal fluid on ultrasound (84%), altered mucous membranes (82%), bacteria noted on the direct smear (67%), hyp...
Robert C, Goachet AG, Fraipont A, Votion DM, Van Erck E, Leclerc JL.Limited information exists about the physiological training-induced changes in electrolyte balance of horses competing in long distance endurance races. Objective: To determine the effects of endurance training and racing on hydration and electrolyte balance in horses. Methods: Blood and urine were sampled at rest in 8 endurance horses before training and after two 11 week training periods (T1 and T2). Each training was followed by a 120 km endurance ride and horses were sampled before, during and 2 h after the rides. Blood was analysed for packed cell volume (PCV), total protein (TP), urea, c...
Spooner HS, Nielsen BD, Schott HC, Harris PA.Excessive sweat loss during endurance exercise may lead to electrolyte disturbances and previous research suggests dietary factors may affect hydration status. While investigating the effect of dietary fibre type on hydration status, sweat samples were collected which allowed for the evaluation of sweat composition in horses consuming forage-based, low sodium (Na) rations. Objective: To investigate sweat composition in Arabian horses performing endurance type exercise while fed forage-based, rations low in Na. Methods: Six 2-year-old Arabian horses were fed, according to a replicated 3 × 3 La...
Norton JL, Nolen-Walston RD, Underwood C, Boston R, Slack J, Dallap BL.Central venous pressure (CVP) is a used as an estimation of intravascular volume status in various species. Techniques for measuring CVP in horses have been described, but the repeatability of these readings at a single time point or over time has not been established. Objective: That CVP measurements in healthy adult horses would be repeatable at each time point, that these readings would be reproducible over time, and that alteration in head position relative to the heart would alter CVP. Methods: Ten healthy adult research horses. Methods: In an experimental study, horses were instrumented ...
Muñoz A, Riber C, Trigo P, Castejón F.Arginine vasopressin (AVP) is released in response to depletion of the effective circulating blood volume. Endurance horses might develop exhaustion because loss of water and electrolytes in sweat with hypovolaemia and electrolytes abnormalities. Therefore, AVP should act in the control of volemia in these animals. This research evaluates the differences in AVP, hydration, electrolyte status and serum muscle enzymes in successful endurance horses in comparison with those eliminated from the competition because of exhaustion. Eighteen endurance horses, divided into two groups, successful (n = 1...
Latman NS, Keith N, Nicholson A, Davis M.A horse's hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference ...
Waller AP, Heigenhauser GJ, Geor RJ, Spriet LL, Lindinger MI.We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrol...
Waller A, Lindinger MI.In human and animal clinical practice, multi-frequency bioelectrical impedance analysis (MF-BIA) is increasingly used as a diagnostic tool to assess hydration of intra-and extracellular fluid compartments. Accurate determination of changes in hydration status within individuals over time has remained problematic due to the requirement for complete impedance-frequency relationships at the time points of interest. Objective: To use MF-BIA in 13 Standardbred racehorses and 7 'endurance' research horses to determine if MF-BIA could be used to track changes in total body water (TBW), intracellular ...
Tennent-Brown BS, Goetz TE, Manohar M, Hassan AS, Freeman DE, Bundy JS, Evans MR.Hyperhydration, prior to prolonged moderate-intensity exercise simulating the 2nd day of a 3-day equestrian event (E3DEC), may induce arterial hypoxaemia detrimental to performance. Objective: Because moderate-intensity exercise does not induce arterial hypoxaemia in healthy horses, the effects of pre-exercise hypervolaemia on arterial oxygenation were examined during a prolonged exercise protocol. Methods: Blood-gas studies were carried out on 7 healthy, exercise-trained Thoroughbred horses in control and hyperhydration experiments. The study conformed to a randomised crossover design. The se...
Schott HC, Marlin DJ, Geor RJ, Holbrook TC, Deaton CM, Vincent T, Dacre K, Schroter RC, Jose-Cunilleras E, Cornelisse CJ.Limited information exists about the physiological changes and clinical problems that occur in elite horses competing in high-speed 160 km endurance races. Objective: To provide initial data describing changes in physiological and laboratory measurements in horses competing in a high-speed, 160 km endurance race under temperate conditions and to compare data between horses that successfully completed the race and those that failed to finish. Methods: Body mass (BM) was measured, blood samples were collected, and veterinary examinations performed on horses before, during, and at the finish of a...
Nyman S, Jansson A, Lindholm A, Dahlborn K.In the present study, the main objective was to study factors affecting postexercise voluntary water intake in horses. Four Standardbred horses (mean +/- s.e. bwt 500 +/- 8 kg) were used to study water intake and effects of altering hydration status before an incremental exercise test (INCR) and a 40 min constant velocity exercise test (CONST) on a treadmill. Exercise was performed during normohydration (N), after dehydration for 24 h (DEH) and after hyperhydration with 12 l water 30 min before exercise (HH). DEH resulted in a bodyweight loss of 3% and there were signs of some fluid uptake pri...
Lindinger MI, McCutcheon LJ, Ecker GL, Geor RJ.This study determined the plasma volume (PV) and ion responses to heat acclimation and exercise in six trained Thoroughbred horses during 21 days of exposure to heat and humidity (33 degrees C, 83% relative humidity) for 4 h/day. During the 2nd h on days 0, 3, 7, 14, and 21, horses performed a standardized treadmill test, running at 50% of peak O(2) uptake until pulmonary artery temperature reached 41.5 degrees C. Heat acclimation resulted in an increase in PV from 21.3 +/- 1.1 liters on day 0 to 24.3 +/- 1.0 liters on day 14, returning to 22.6 +/- 0.9 liters on day 21. The corresponding total...
Lindinger MI.This paper reviews the limits to exercise imposed by increases in ambient, hypothalamic, and contracting skeletal muscle temperature in humans and horses. Like humans, horses frequently compete in hot environments, yet their high mass-specific rate of heat production and low mass-specific surface area for heat dissipation places them at a great disadvantage compared to humans. Exercise in hot conditions increases the rate of body heat storage and reduces the time required to reach a critical hypothalamic temperature that results in voluntary fatigue. This critical temperature appears to be ass...
Kasapi MA, Gosline JM.Possible functions of equine hoof wall tubules were investigated in this study. Hydration tests were conducted on blocks of hoof wall tissue in order to test the hypothesis that hollow tubules facilitate the conduction of water vapour distally. Although water loss or gain was inhibited through the outer wall surface, the increase in surface area provided by medullary spaces was ineffective in facilitating hydration through the face with exposed tubule ends. Rather, hollow tubules appear to allow for a higher dehydration rate through their exposed ends. Analysis of medullary space indicates tha...
Geor RJ, McCutcheon LJ.This study examined the effects of hyperhydration, exercise-induced dehydration, and oral fluid replacement on physiological strain of horses during exercise-heat stress. On three occasions, six horses completed a 90-min exercise protocol (50% maximal O2 uptake, 34.5 degrees C, 48% relative humidity) divided into two 45-min periods (exercise I and exercise II) with a 15-min recovery between exercise bouts. In random order, horses received no fluid (NF), 10 liters of water (W), or a carbohydrate-electrolyte solution (CE) 2 h before exercise and between exercise bouts. Compared with NF, preexerc...
Bertram JE, Gosline JM.Tensile moduli and J-integral fracture toughness values were determined for horse hoof-wall keratin at four hydration levels. The stiffness of hoof-wall was influenced by water content to a greater degree than is the stiffness of other mammalian hard keratins. Young's modulus increased from 410 MPa at 100% relative hydration (RH) to 14.6 GPa at 0% RH. Fracture toughness was maximal (22.8 kJ m-2) at an intermediate hydration (75% RH), which represents a two-fold increase over both fully hydrated and dehydrated material. Maximum fracture toughness occurred at a hydration level which is within th...
McCutcheon LJ, Geor RJ, Hare MJ, Ecker GL, Lindinger MI.The objective of this study was to determine the composition and extent of sweat losses during submaximal exercise under hot and humid conditions and to compare these findings with the same exercise protocol conducted under cool, dry and hot, dry conditions. Five Thoroughbred horses (age 3 to 6) completed exercise tests under each of 3 environmental conditions in random order: cool, dry (CD), room temperature (T) = 20 degrees C, relative humidity (RH) = 45-55%; hot, dry (HD), T = 32-34 degrees C, RH = 45-55%; and hot, humid (HH), T = 32-34 degrees C, RH = 80-85%. Horses exercised at 50% of the...
Robert C, Goachet AG, Fraipont A, Votion DM, Van Erck E, Leclerc JL.Limited information exists about the physiological training-induced changes in electrolyte balance of horses competing in long distance endurance races. Objective: To determine the effects of endurance training and racing on hydration and electrolyte balance in horses. Methods: Blood and urine were sampled at rest in 8 endurance horses before training and after two 11 week training periods (T1 and T2). Each training was followed by a 120 km endurance ride and horses were sampled before, during and 2 h after the rides. Blood was analysed for packed cell volume (PCV), total protein (TP), urea, c...
Schott HC, Marlin DJ, Geor RJ, Holbrook TC, Deaton CM, Vincent T, Dacre K, Schroter RC, Jose-Cunilleras E, Cornelisse CJ.Limited information exists about the physiological changes and clinical problems that occur in elite horses competing in high-speed 160 km endurance races. Objective: To provide initial data describing changes in physiological and laboratory measurements in horses competing in a high-speed, 160 km endurance race under temperate conditions and to compare data between horses that successfully completed the race and those that failed to finish. Methods: Body mass (BM) was measured, blood samples were collected, and veterinary examinations performed on horses before, during, and at the finish of a...
O'Reilly J, Cheng HL, Poon ET.Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the "in-race" heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. "In-race" HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (le...
Nyman S, Jansson A, Lindholm A, Dahlborn K.In the present study, the main objective was to study factors affecting postexercise voluntary water intake in horses. Four Standardbred horses (mean +/- s.e. bwt 500 +/- 8 kg) were used to study water intake and effects of altering hydration status before an incremental exercise test (INCR) and a 40 min constant velocity exercise test (CONST) on a treadmill. Exercise was performed during normohydration (N), after dehydration for 24 h (DEH) and after hyperhydration with 12 l water 30 min before exercise (HH). DEH resulted in a bodyweight loss of 3% and there were signs of some fluid uptake pri...
Kiely M, Warrington GD, McGoldrick A, Pugh J, Cullen S.Kiely, M, Warrington, GD, McGoldrick, A, Pugh, J, and Cullen, S. Physiological demands of professional flat and jump horse racing. J Strength Cond Res 34(8): 2173-2177, 2020-No information is currently available on the effect of race distance on the physiological demands of jockeys. This study aimed to quantify the respective demands of short and long flat and jump race distances. Twenty professional jockeys (10 flat and 10 jump) participated in the study. The subjects initially performed a graded incremental exercise test to volitional exhaustion on a treadmill to determine the peak heart rat...
Nógrádi N, Tóth B, Macgillivray KC.Factors associated with the outcome of peritonitis in horses are seldom described. The objectives of this study were to determine the common clinical signs and clinicopathologic findings and to reveal prognostic factors associated with the outcome of peritonitis in equine patients. Data were examined in a retrospective manner in 55 horses diagnosed with and treated for peritonitis. The most common clinical and clinicopathologic findings were tachycardia (94%), increased amount of peritoneal fluid on ultrasound (84%), altered mucous membranes (82%), bacteria noted on the direct smear (67%), hyp...
Waller AP, Heigenhauser GJ, Geor RJ, Spriet LL, Lindinger MI.We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrol...
Geor RJ, McCutcheon LJ.This study examined the effects of hyperhydration, exercise-induced dehydration, and oral fluid replacement on physiological strain of horses during exercise-heat stress. On three occasions, six horses completed a 90-min exercise protocol (50% maximal O2 uptake, 34.5 degrees C, 48% relative humidity) divided into two 45-min periods (exercise I and exercise II) with a 15-min recovery between exercise bouts. In random order, horses received no fluid (NF), 10 liters of water (W), or a carbohydrate-electrolyte solution (CE) 2 h before exercise and between exercise bouts. Compared with NF, preexerc...
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...
Fielding CL, Dechant JE.Colic is a common reason for elimination from equine endurance competitions and has recently been identified as the leading cause of mortality in this group of horses. Hydration and electrolyte derangements are often severe, but are probably related to endurance exercise and not necessarily the episode of colic. Better understanding of the causes of colic and the expected outcome is needed to guide treatment decisions in endurance horses. Objective: To describe the history, case details, clinical examination, laboratory, treatment and outcomes for horses presenting to equine referral centres f...
Kingston JK, Geor RJ, McCutcheon LJ.Rate and ionic composition of sweat fluid losses and partitioning of evaporative heat loss into respiratory and cutaneous components were determined in six horses during three 15-km phases of exercise at approximately 40% of maximal O2 uptake. Pattern of change in sweat rate (SR) and composition was similar during each phase. SR increased rapidly for the first 20 min of exercise but remained at approximately 24-28 ml . m-2 . min-1 during the remainder of each phase. Similarly, the concentrations of Na and Cl in sweat increased until 30 min of exercise but were unchanged thereafter. Sweat osmol...
Waller AP, Lindinger MI.Exercise results in rapid and large extracellular to intracellular fluid shifts, as well as significant sweating losses of water and ions. It is unknown whether ions within oral electrolyte supplements are taken up by muscle (and other soft tissues) and whether oral supplementation can effectively offset sweating losses. Pre-loading with 8 L of a balanced hypotonic electrolyte supplement attenuated extracellular fluid losses, increased exercise duration and increased sweating fluid and ion losses during submaximal exercise. Supplemented electrolytes appear in skeletal muscle within 1 h after...
Lindinger MI.This paper reviews the limits to exercise imposed by increases in ambient, hypothalamic, and contracting skeletal muscle temperature in humans and horses. Like humans, horses frequently compete in hot environments, yet their high mass-specific rate of heat production and low mass-specific surface area for heat dissipation places them at a great disadvantage compared to humans. Exercise in hot conditions increases the rate of body heat storage and reduces the time required to reach a critical hypothalamic temperature that results in voluntary fatigue. This critical temperature appears to be ass...
Martel P, Calmettes P, Hennion B.Equine red blood cells were washed in saline heavy water (2H2O) to exchange the hydrogen atoms of the non-hemoglobin components with deuterons. This led to novel neutron scattering measurements of protein vibrations within a cellular system and permitted a comparison with inelastic neutron scattering measurements on purified horse hemoglobin, either dry or wetted with 2H2O. As a function of wavevector transfer Q and the frequency transfer v the neutron response typified by the dynamic structure factor S(Q, v) was found to be similar for extracted and cellular hemoglobin at low and high tempera...
Akbari Shahkhosravi N, Gohari S, Komeili A, Burvill C, Davies H.Most simulation studies on equine hoof biomechanics employed linear elastic (LE) material models. However, the equine hoof wall's stress-strain relationship is nonlinear and varies with hydration level. Therefore, it is essential to investigate the accuracy of the LE model compared to more advanced material models, such as hyperelastic (HE) or viscoelastic models. The current research investigated performances of LE and three HE models (Mooney-Rivlin, Neo-Hookean, and Marlow) in describing equine hoof's mechanical behavior using finite element (FE) analysis. In the first attempt, a rectangular...
Muñoz A, Riber C, Trigo P, Castejón F.Arginine vasopressin (AVP) is released in response to depletion of the effective circulating blood volume. Endurance horses might develop exhaustion because loss of water and electrolytes in sweat with hypovolaemia and electrolytes abnormalities. Therefore, AVP should act in the control of volemia in these animals. This research evaluates the differences in AVP, hydration, electrolyte status and serum muscle enzymes in successful endurance horses in comparison with those eliminated from the competition because of exhaustion. Eighteen endurance horses, divided into two groups, successful (n = 1...
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...
Waller A, Lindinger MI.In human and animal clinical practice, multi-frequency bioelectrical impedance analysis (MF-BIA) is increasingly used as a diagnostic tool to assess hydration of intra-and extracellular fluid compartments. Accurate determination of changes in hydration status within individuals over time has remained problematic due to the requirement for complete impedance-frequency relationships at the time points of interest. Objective: To use MF-BIA in 13 Standardbred racehorses and 7 'endurance' research horses to determine if MF-BIA could be used to track changes in total body water (TBW), intracellular ...
Spooner HS, Nielsen BD, Schott HC, Harris PA.Excessive sweat loss during endurance exercise may lead to electrolyte disturbances and previous research suggests dietary factors may affect hydration status. While investigating the effect of dietary fibre type on hydration status, sweat samples were collected which allowed for the evaluation of sweat composition in horses consuming forage-based, low sodium (Na) rations. Objective: To investigate sweat composition in Arabian horses performing endurance type exercise while fed forage-based, rations low in Na. Methods: Six 2-year-old Arabian horses were fed, according to a replicated 3 × 3 La...
Sneddon JC, van der Walt JG, Mitchell G.This study set out to investigate tolerance of the body water pool to short-term water deprivation in horses and, in particular, to assess whether feral horses from the Namib Desert showed tolerance to dehydration superior to Transvaal. Hydration status was compared in six feral horses from the Namib Desert and in six Boerperd farm horses under conditions of normal hydration and after 72 h of dehydration. Under normal hydration, the two groups did not differ significantly in water intake, plasma sodium and potassium concentrations, plasma osmolality, hematocrit, total plasma protein, body wate...
Lindinger MI.Horses that sweat for prolonged periods lose considerable amounts of water and electrolytes. Maintenance of hydration and prevention of dehydration requires that water and electrolytes are replaced. Dehydration is common in equine disciplines and can be avoided, thus promoting equine wellness, improved performance and enhanced horse and rider safety. Significant dehydration occurs through exercise or transport lasting one hour or more. Oral electrolyte supplementation is an effective strategy to replace water and electrolytes lost through sweating. The stomach and small intestine serve as a re...
Ecke P, Hodgson DR, Rose RJ.Hydration status, electrolyte balance and acid-base balance were studied in four adult standardbred geldings with castor oil-induced diarrhoea. The horses received an oral rehydration solution (ORS) at a point when signs consistent with mild decreases in effective circulating fluid volume were first detected. Within 1.5 h of ORS administration, all horses exhibited a significant metabolic acidosis. At this time, mean values for venous blood pH, [HCO3], and standard base excess were 7.264 +/- 0.011, 17.7 +/- 0.3 mmol L-1, and -8.2 +/- 0.4 mmol L-1, respectively. Throughout the duration of the s...
Lindinger MI, McCutcheon LJ, Ecker GL, Geor RJ.This study determined the plasma volume (PV) and ion responses to heat acclimation and exercise in six trained Thoroughbred horses during 21 days of exposure to heat and humidity (33 degrees C, 83% relative humidity) for 4 h/day. During the 2nd h on days 0, 3, 7, 14, and 21, horses performed a standardized treadmill test, running at 50% of peak O(2) uptake until pulmonary artery temperature reached 41.5 degrees C. Heat acclimation resulted in an increase in PV from 21.3 +/- 1.1 liters on day 0 to 24.3 +/- 1.0 liters on day 14, returning to 22.6 +/- 0.9 liters on day 21. The corresponding total...
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...
Latman NS, Keith N, Nicholson A, Davis M.A horse's hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference ...
