bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma total CO2and electrolytes: diurnal changes and effects of adrenaline, doxapram, rebreathing and transport
Authors: SLOCOMBE R. F. , HUNTINGTON P. J. , LIND KAREN L. , VINE J. H. 
Published: June 2010

SummaryPre‐race testing for plasma bicarbonate is used in Australia to detect administration of large doses of bicarbonate or other alkalising agents. The rules specify upper limits for plasma TCO2from 35 to 37 mmol/l, depending on State. There has been considerable speculation about physiological factors that may increase plasma total CO2and lead to infringements of this rule. In order to address these purported influences, we measured body temperature (BT), heart rate (HR), haemoglobin concentration (Hb), packed cell volume (PCV), TCO2, potassium [K], sodium [Na], chloride [Cl] and breathing frequency (Fb) in 6 horses under the following conditions: rebreathing into a 3 litre bag for 90 s following respiratory stimulation with doxapram (0.5 mg/kg bwt i.v.); following excitement and during sweating induced by adrenaline (2.5 mg/kg bwt i.v.).We also evaluated whether significant diurnal variation existed in plasma electrolytes. There was no diurnal variation in sodium but potassium and chloride peaked in the evening and were lowest at early morning. TCO2changes were also significant with peak values occurring before noon. Rebreathing produced transient marginal increases in TCO2and potassium, declines in chloride and no change in sodium. The rise in TCO2was from 29.6 ± 0.8 to 30.9 ± 1.4 mmol/l. Animals became markedly agitated by 90 s of rebreathing. Doxapram caused a 2‐fold increase in Fb, a small (<1 mmol/l) increase in TCO2, marginal increases in sodium and potassium, but no change in chloride. Adrenaline caused marked sweating and anxiety in all horses and led to increased HR, sodium, chloride, PCV and Hb, caused decreased TCO2(<2 mmol/l), decreased chloride and had no consistent effect on BT.From these studies, we conclude that rebreathing, hyperpnoea induced by doxapram and sweating and excitement induced by adrenaline, in otherwise healthy horses, exerts only marginal effects on TCO2. Differences were significant for all measured electrolytes between horses, with magnitudes exceeding changes induced by experimental protocols. Mean TCO2for individual horses ranged from 26.5 ± 0.3 to 33.8 ± 0.2 mmol/l in the adrenaline trial with similar ranges in other studies.
Comparison between two post exercise cooling methods
Authors: WILLIAMSON LISA , WHITE S. , MAYKUTH P. , ANDREWS F. , SOMMERDAHL C. , GREEN E. 
Published: June 2010

SummaryForty‐two fit 3‐day‐event horses were tested under hot, humid ambient conditions to determine if application of cold water (mean 9°C) over the entire body surface after exercise would cool horses more quickly than regional application of tepid water (mean 31°C); and to determine if topical application of cold water caused myopathy. Horses were exercised under saddle for an average of 81 min. Heart rate data and post exercise plasma lactate concentrations characterised the work effort as low intensity work with short bouts of moderate intensity effort.Sixteen horses were studied in a crossover design on 2 consecutive days. Immediately after exercise, horses were randomly assigned to the hypercooling protocol (cold water on entire body surface) or the conventional protocol (tepid water on neck, shoulders, torso, underside and legs). Hypercooled horses (Group 1) had significantly lower rectal temperatures at 15, 20, 25 and 30 min after exercise compared to conventionally cooled horses (Group 2). In a supplemental study, an additional 19 horses (Group 3) were hypercooled after exercise. Mean rectal temperatures were significantly decreased from the immediate post exercise rectal temperature at 10, 15, 20 and 25 min after exercise. Based on physical examination and serum AST and CK concentrations, myopathy did not occur in any of the horses. These results suggest that application of cold water to the entire body surface relieves mild to moderate exertional hyperthermia quickly under hot, humid conditions; and that myopathy is not a common complication of this cooling approach.
Adaptation of Thoroughbred horses in training to a fat supplemented diet
Authors: HUGHES S. J. , POTTER G. D. , GREENE L. W. , ODOM T. W. , MURRAY‐GERZIK M. 
Published: June 2010

SummaryEight Thoroughbred horses were used in a repeated measures, crossover experiment in which horses were fed a fat supplemented and control diet. On Days 0, 7,14, 21 and 28, horses performed a standardised exercise test (SET) consisting of three 400 m sprints. Digestion trials were performed over 3 days prior to each SET and muscle biopsies were taken pre‐ and post SET. Feeding fat had no negative effect (P>0.05) on digestion of any diet constituent and digestive adaptation to the fat supplemented diet apparently occurred within 1 week. Pre‐exercise muscle glycogen concentrations increased up to Day 14 on both diet treatments. However, when horses were fed the fat supplemented diet pre‐SET muscle glycogen concentration increased until Day 21 (P<0.05) at which time it was higher (P<0.05) than when the horses were fed the control diet. This difference was also present at Day 28. Post SET muscle glycogen concentrations were similar (P>0.05) between treatments on all sampling days. In fat supplemented horses, muscle glycogen utilisation during the SET was increased on both treatments to Day 14 (P<0.05) and increased further to Day 21 when the horses were fed the fat supplemented diet. On Days 21 and 28, glycogen utilisation during the SET was greater (P<0.05) when horses were fed the fat supplemented diet than when fed the control diet.
Effects of post prandial interval and feed type on substrate availability during exercise
Authors: STULL CAROLYN , RODIEK ANNE 
Published: June 2010

SummaryThe glycaemic and lipaemic effects of 3 feeding regimes and 2 post prandial intervals were determined at rest and during exercise using 6 Thoroughbred geldings on 6 testing days according to a Latin square design. Three feeding regimes consisted of a fasting regime and isoenergetic meals (4.1 Mcal) of either cracked corn or alfalfa. One or 4 h after feeding, a standardised exercise test (SET) was imposed on fed and fasted horses. Blood was sampled via jugular catheters every 15 min from 0630 to 1500 h, except during the 55 min SET in which 7 samples were drawn. The SET consisted of three 10 min bouts of saddling, walking to the arena and warm‐up (walking and trotting), followed by 3 bouts of progressively more intense cantering at heart rates of 130–140 (10 min), 150–160 (10 min) and 170–180 (5 min) beats/min. There were no feeding regime effects on pre‐feeding levels of glucose, insulin, lactate, glycerol or free fatty acids (FFA). However, glucose in corn fed horses fell below pre‐feeding concentration during the SET but rebounded at the termination of cantering. Glucose in alfalfa fed and fasted horses gradually rose throughout the SET. Insulin levels closely followed glucose response. During the SET, corn fed horses had higher insulin concentrations (P<0.05) than fasted or alfalfa fed horses. During the onset of the SET one or 4 h post prandially, FFA levels in corn fed horses were less (P<0.05) than in alfalfa fed or fasted horses. Glycerol levels gradually increased during the SET; however, no differences were found between dietary treatments.
Effect of diet on weight and plasma variables in endurance exercised horses
Authors: DANIELSEN KRISTIN , LAWRENCE L. M. , SICILIANO P. , POWELL DEBBIE , THOMPSON K. 
Published: June 2010

SummaryThe purpose of this study was to determine whether a difference in roughage intake could affect electrolyte and water balance in horses during endurance type exercise. In each of 2 experiments, 2 treatments (a high hay or limited hay diet) were assigned in a crossover design so that each horse performed 2 exercise tests, 1 on each treatment. In experiment 1, diet was controlled only the night before the exercise test. Water intake was lower (P<0.001) when horses received the limited hay diet. Exercise caused a decrease in plasma chloride and potassium concentration and an increase in plasma total protein concentration, but there were no diet differences (P>0.05). Weight loss was 2.8% of body weight for both treatments. In experiment 2, horses were adapted to the diets for 7 days prior to the exercise test. Again, water intake was lower when the horses received the limited hay diet (P<0.01). During exercise, both groups lost about 4% of bodyweight, but total protein concentration was lower (P<0.05) in the horses receiving the high hay diet. Plasma potassium concentration initially increased and then decreased during exercise (P<0.05), but the horses receiving the high hay diet maintained a higher potassium concentration during exercise (P<0.05). Sodium was not affected by diet or exercise (P>0.05). Plasma chloride concentration decreased during exercise (P<0.05). The increased water intake and lower plasma protein concentration associated with the hay diet may be beneficial for horses involved in endurance type exercise.
Performance at high altitude of horses and mules receiving fat supplemented diets
Authors: WICKLER S. J. , PAULEY P. S. , BRAY R. E. , LONDON C. , GABBARD MARIE 
Published: June 2010

SummaryThe purpose of this study was to 1) evaluate and compare the athletic performance of 14 horses and 16 mules, working at high altitude (2700 to 4000 m) in the course of a commercial pack station routine and 2) assess the effect of fat supplementation (10% by weight) on performance. Lactate, haemoglobin, glucose and free fatty acid (FFA) concentrations were measured on Day 1 (prior to supplementation, animals at rest) and then each day thereafter from day 3–7 (i.e. a total of 6 samples for each animal) after an exercise test. Exercise tests ranged in power requirements from 160–730 J/s. Lactate concentrations were increased after the exercise bouts (P=0.029) and were positively correlated (r=0.93) to power. However the value for lactate concentrations indicated that these animals were working well below maximal intensities (mean ± s.e. 1.19 ± 0.1 mmol/l at the most intense work load) and there were no differences between mules and horses. Haemoglobin concentrations were also correlated with power (r=0.79). Glucose and FFA concentrations were increased after exercise. Fat supplemented animals maintained blood glucose concentrations higher than controls and had higher FFA concentrations after the first exercise bout. The only difference between mules and horses was noted after the most intense exercise period: FFA concentrations were higher in mules than horses during exercise.
Effects of weight and riding on workload and locomotion during treadmill exercise
Authors: VAN OLDRUITENBORGH‐OOSTERBAAN MARIANNE M. SLOET , BARNEVELD A. , SCHAMHARDT H. C. 
Published: June 2010

SummaryTo answer the question whether an experienced rider or a dead weight influences a horse's workload and/or its locomotion, 9 well trained Dutch Warmblood horses, fully accustomed to treadmill exercise, underwent a submaximal standardised treadmill exercise test under 3 different conditions: unloaded, mounted by an experienced rider of 90 kg and loaded with 90 kg of lead. Heart rate was monitored continuously and plasma lactate concentrations were determined in venous jugular blood samples immediately before and 2 and 10 min after exercise. Temporal and angular stride variables were measured in fore‐ and hindlimbs at the walk (1.7 m/s), trot (4.0 m/s) and canter (7.0 m/s) with a modified CODA‐3 computerised kinematic analysis system. Peak heart rates during exercise, and recovery heart rates thereafter were significantly lower in the unloaded horses compared to the mounted and lead‐loaded horses. Plasma lactate concentrations immediately and 10 min after exercise were also significantly lower in the unloaded horses than in the mounted and lead‐loaded horses. No differences were found in heart rate and plasma lactate concentration between the mounted and lead‐loaded horses. Relative stance duration increased comparing the unloaded to the mounted and the lead‐loaded horses (P<0.05). Small, but significant, differences were also observed in the fetlock extension and the maximal fetlock range of motion; both increased with loading. In conclusion, an experienced rider and a dead weight influence both workload and locomotion in exercising horses. Minimal differences were found between dead lead weight and a rider.
Indices of exercise capacity in horses presented for poor racing performance
Authors: ROSE R. J. , KING C. M. , EVANS D. L. , TYLER C. M. , HODGSON D. R. 
Published: June 2010

SummaryWe examined 106 Thoroughbred (TB) and 51 Standardbred (SB) racehorses that were presented because of poor performance. All horses were in training and had raced within 2 weeks of presentation. Horses were acclimatised (2–4 runs) and tested on a treadmill set at a 10% slope. The exercise test consisted of 3 min at 4 m/s, 2 min at 6 m/s, then 1 min steps at 8, 10, 11, 12 and 13 m/s or until the horse could not maintain pace with the treadmill. At the end of each speed, arterial blood and expired gas samples were collected and heart rate recorded. Measurements during the test included: arterial blood gas tensions, plasma lactate concentration [LA], V̇O2, V̇CO2, O2 pulse (V̇O2/HR), heart rate, maximum stride length (SLmax), post exercise haematocrit (PCVPE), total red cell volume (CV) and total run time. The TB ran longer than SB (522 vs. 477 s) and had higher values for CV, PCVPE, V̇O2max, V̇O2‐200, maximum O2 pulse, V200, VHRmax, post exercise [LA] ([LAPE]) and SLmax. There were no breed differences for VLA4 and PaO2 at 10 m/s. In the TB, significant correlations (Spearman's rank order) (P<0.01) were found for treadmill run time with: PCVPE, V̇O2max, V̇O2–200, peak O2 pulse, PaO2 at 10 m/s, PaCO2 at 10 m/s, V200, VLA4, [LAPE], VHRmax, maximum blood temperature and SLmax. In the SB significant but lower correlations (P<0.05) were found for treadmill run time with: PCVPE, V̇O2max, V200, VLA4, [LAPE], VHRmax, maximum blood temperature and SLmax. While these results may not be applicable to normal racehorses, the indices which correlated best with treadmill run time were generally those indicating a high capacity for oxygen transport.
Effects of exercise on erythrocytes in normal and splenectomised Thoroughbred horses
Authors: HANZAWA K. , KUBO K. , KAl M. , HIRAGA A. , WATANABE S. 
Published: June 2010

SummaryChanges in erythrocyte quality during exercise were determined in 3 control (Group C) and 3 splenectomised (Group 5) horses that performed an incremental exercise test on a treadmill until the point of fatigue. Venous blood samples were drawn before the exercise test and immediately after warming‐up and incremental exercise test. Incremental exercise increased erythrocyte count and haemoglobin concentration by 46 and 37% respectively in control horses and by 15 and 17% respectively inGroup Sanimals. Packed cell volume (PCV) increased by 48% in controls but there was no change inGroup Sanimals. Warming‐up decreased mean cell volume (MCV), mean cell Hb (MCH) and mean cell Hb concentration (MCHC) by 9, 19 and 7% in control horses. Incremental exercise restored MCV and MCHC but MCH remained lower than the resting level. InGroup Shorses, warming‐up and incremental exercise decreased MCV by 6 and 9% respectively, did not change MCH, but increased MCHC by 4 and 15% respectively. Incremental exercise increased erythrocyte density (ED) inGroup Cbut not inGroup Shorses. Osmotic fragility of erythrocytes measured as the red cell haemolysis rates in 0.56% NaCl (HL) were significantly higher inGroup Cthan inGroup Shorses regardless of exercise. Warming‐up decreased HL by 7% inGroup Cvs 19% inGroup Shorses, but exercise increased HL by 26% inGroup Cvs 38% inGroup Shorses. These results suggest that: 1) exercise causes shrinking of erythrocytes; 2) erythrocyte indices are dependent on the intensity of the exercise; 3) release of erythrocytes from the spleen is associated with an increase in osmotic fragility; and 4) exercise changes osmotic fragility regardless of the release of erythrocytes from the spleen into circulation.
Acclimation to treadmill exercise
Authors: KING C. M. , EVANS D. L. , ROSE R. J. 
Published: June 2010

SummaryAcclimation to treadmill exercise and to a respiratory gas collection mask were studied in 3 groups of Thoroughbred or Standardbred horses. Heart rate and plasma lactate concentration were measured at rest and at the completion of each speed increment during a series of acclimating runs at 4, 6 and 8 m/s on a treadmill inclined at a 10% slope. No significant differences were found in the heart rate at 4, 6 or 8 m/s between acclimating runs for any of the groups, except for a reduction between runs 1 and 2 at 4 m/s in a group of 19 racehorses that received 2 acclimating runs (Group 1). Heart rate values at 4 and 6 m/s were significantly higher during the subsequent exercise test in a group of 12 racehorses that received 4 prior acclimating runs (Group 3). Plasma lactate concentration was significantly reduced at 4 and 6 m/s from run 1 to 2 in Group 1 and at all speeds in a group of 6 experimental horses (Group 2) between run 1 and subsequent runs. There was also a significant reduction in plasma lactate concentrations at 6 and 8 m/s between runs 2 and 4 in Group 2 and between runs 3 and 4 at 8 m/s. A temperament scoring system was used to describe the behaviour of the horse on the treadmill. With the exception of 1 horse, the temperament score improved significantly, indicating acclimation to the treadmill after the first acclimating run in Groups 2 and 3. We conclude that acclimation occurred in the majority of horses after 1 or 2 exposures to treadmill exercise and a gas collection mask. However, there was substantial variability between horses and care must be taken when interpreting submaximal heart rate and plasma lactate data. This has important implications for the use of common measurements of exercise capacity such as V200 and VLA4, which rely on values obtained during submaximal exercise.
Modelling impact‐initiated wave transmission through lung parenchyma in relation to the aetiology of exercise‐induced pulmonary haemorrhage
Authors: SCHROTER R. C. , LEEMING A. , DENNY E. , BHARATH A. , MARLIN D. J. 
Published: June 2010

SummaryRecently we proposed that exercise‐induced pulmonary haemorrhage (EIPH) results from locomotory‐impact‐induced trauma by impact of the scapula on the chest wall during footfall and the consequent transmission of waves through the lung. A computational model has been developed to demonstrate that wave amplification and focusing occur in the dorsocaudal tip of the lung for waves originating on the anterior subscapular surface. The propagation of an acoustic wave was investigated in a simplified 2‐dimensional representation of a vertical anterio‐dorsal section of horse lung. It was demonstrated that a complicated pattern of waves is transmitted from the scapula to the dorsal region. Wave motion was characterised using the instantaneous rate of change of pressure with time (dp/dt) which is associated with lung injury. Due to wave reflection and focusing, dp/dt is transiently very high on the spinal and diaphragmatic lung walls, particularly in the vicinity of the dorsal tip. The model therefore predicts that lung injury may occur in the region in which EIPH is reported to originate.
Is ventilation during maximal exercise limited by dynamic airway closure?
Authors: HOBO S. , HIRAGA A. , BIRKS E. K. , TAKAHASHI T. , HADA T. , JONES J. H. 
Published: June 2010

SummaryA study was undertaken to And if the reason why horses hypoventilate when running is that they experience expiratory flow limitation due to dynamic airway closure. To test this hypothesis, we measured peak expiratory flows on a Thoroughbred galloping on a treadmill and hypoventilating and compared those flows with the peak dynamically‐limited flow that the same horse could achieve during a forced expiratory flow‐volume manoeuvre. At the approximate lung volumes at which the horse was ventilating while running, it did not appear to be mechanically limited and appeared to have reserve capacity available potentially to increase its expiratory flow.
Pathophysiology of dorsal displacement of the soft palate in horses
Authors: HOLCOMBE SUSAN J. , DERKSEN F. J. , STICK J. A. , ROBINSON N. E. 
Published: June 2010

SummaryDorsal displacement of the soft palate (DDSP) is an intermittent obstructive upper airway condition that occurs in athletic horses during high‐intensity exercise. The pathogenesis of this condition is unknown, but may involve epiglottic hypoplasia, malformation, or neuromuscular dysfunction. In this paper, we report on investigations into the pathophysiology of DDSP. In 3 separate experiments, Standardbred horses were exercised on a high‐speed treadmill at speeds corresponding to 50, 75 and 100% of maximum heart rate. The upper airway was evaluated by videoendoscopy and measurement of tracheal pressures.Inexperiment 1, we examined the effect of bilateral hypoglossal and glossopharyngeal nerve block on epiglottic function in exercising horses. This nerve block caused epiglottic retroversion and inspiratory upper airway obstruction. However, DDSP did not occur. Inexperiment 2, we evaluated the hypothesis thattensor veli palatinimuscle dysfunction is involved in the pathogenesis of DDSP. Bilateraltensor veli palatinimuscle tenectomy did not cause DDSP, but caused instability of the rostral half of the soft palate and a modest inspiratory upper airway obstruction. Inexperiment 3, we hypothesised thatpalatinusand palatopharyngeal dysfunction causes DDSP. The pharyngeal branch of the vagus nerve was blocked bilaterally in the guttural pouch. This block caused DDSP in all horses within 2–15 min after nerve block. Furthermore, DDSP created an expiratory nasopharyngeal obstruction. Because the pharyngeal branch of the vagus nerve is in close proximity to the retropharyngeal lymph node chain, we suggest that retropharyngeal lymphadenopathy may cause neural dysfunction and thereby be involved in the pathogenesis of clinical DDSP.
Differences in the ventilatory responses of horses and ponies to exercise of varying intensities
Authors: KATZ LISA M. , BAYLY W. M. , HINES MELISSA T. , SIDES R. H. 
Published: June 2010

SummaryHorses exercising at ˜90% V̇o2maxdevelop arterial hypoxaemia with concurrent hypercapnoea, whereas ponies exercising at comparative levels become hypocapnoeic and maintain arterial oxygen tensions close to resting values. We sought to investigate the possibility that these differences relate to the ventilatory responses of these animals to exercise. Six Thoroughbred horses weighing mean ± s.e. 501 ± 27 kg and 5 ponies weighing mean ± s.e. 164 ± 18 kg exercised for 2 min on a 10% slope at speeds calculated to require 60% V̇o2maxand for at least 1 min at speeds calculated to require 115% V̇o2max. Oxygen consumption (V̇o2), arterial oxygen (Pao2) and carbon dioxide (Paco2) tensions, acid‐base balance, tidal volume (VT), minute ventilation (V̇E), peak inspiratory (V̇Imax) and expiratory (V̇Emax) flow, and maximal changes in transpulmonary pressures (ΔPtpmax) were measured immediately before exercise and in the last 15 s of exercise at each intensity. The results confirmed that, unlike horses, ponies do not become hypoxaemic or hypercapnoeic during exercise. Despite having a higher ΔPtpmax, higher V̇Imaxand V̇Emaxand V̇E/kg0.75at the same relative intensities, horses were less capable of mounting an appropriate ventilatory response to exercise. This was reflected by lower mass specific and metabolic weight‐based ventilations at similar absolute workloads, and their higher Paco2and arterial [HCO3−]> and lower ventilatory equivalent for oxygen (V̇E/V̇o2). This suggests that horses become hypoxaemic and hypercapnoeic at work loads ˜90% V̇o2maxbecause their metabolic demand surpasses the capacity of their ventilatory system to meet this demand. Because ponies are less capable athletes, they can match their ventilatory response to their metabolic requirements.