bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of exercise on concentrations of immunoreactive endothelin in bronchoalveolar lavage fluid of normal horses and horses with chronic obstructive pulmonary disease
Authors: BENAMOU AGNES E. , ART TATIANA , MARLIN D. J. , ROBERTS C. A. , LEKEUX P. 
Published: June 2010

SummaryChronic obstructive pulmonary disease (COPD) represents a major cause of loss of performance in the horse. The role of endothelin (ET), a potent bronchoconstrictive and vasoactive peptide, is currently being investigated in asthma and other obstructive respiratory diseases in man. We have previously found elevated systemic and pulmonary endothelin levels in horses during exacerbation of COPD. In the present study, our aim was to examine possible variations in ET concentrations occurring during exercise in COPD horses. We compared the effects of intense treadmill exercise on the recovery of endothelin (ET) in the bronchoalveolar lavage fluid (BALF) as well as in arterial and venous blood, in a group of 5 healthy horses and a group of 5 COPD horses studied alternately in remission and while symptomatic. We also investigated the possible correlations between ET levels and pulmonary function tests during the study.While exercise did not affect the ET levels recovered in BALF among controls, it caused a significant increase (P = 0.02) among symptomatic COPD horses. During remission, wide variations of ET levels among horses, at rest and during exercise, made any significant interpretation difficult. No correlation could be found between exercise‐induced changes in ET concentrations and pulmonary function tests or changes in arterial oxygen tension with exercise. We conclude that exercise appears to affect the release of ET by the airways in COPD horses, in contrast to healthy horses. It is still unclear, however, whether these differences relate to adjustments of lung function during exercise.
Ventilation‐perfusion relationships during exercise in Standardbred trotters with red cell hypervolemia
Authors: FUNKQUIST PIA , WAGNER P. D. , HEDENSTIERNA G. , PERSSON S. G. B. , NYMAN GÖREL 
Published: June 2010

SummaryIn order to evaluate the pulmonary gas exchange during exercise in Standardbred trotters with red cell hypervolaemia (RCHV), 12 horses with RCHV were compared with 9 normovolaemic (NV) horses. V̇o2 and V̇co2 were determined with an open bias flow system. Cardiovascular and haemodynamic data were recorded during exercise at 4 different speeds on a treadmill. Pulmonary gas exchange was assessed by conventional blood gas variables (arterial and mixed venous blood gas tensions), and the ventilation‐perfusion distribution V̇A/Q̇ was estimated by the multiple inert gas elimination technique. V̇A and AaDo2 were calculated. Dispersions of perfusion and ventilation distribution (SDQ, SDV) were determined.HR, RR, Q̇t, V̇o2, V̇A, log SDV, C(a‐***v)o2 and lactate did not differ between groups. The degree of hypoxaemia was more pronounced in the RCHV than in the NV (Pao2 = 54 and 59 mmHg; AaDO2 = 41 and 34 mmHg in RCHV and NV, respectively, at highest workload). Further, pH was lower in the RCHV and Paco2 and V̇CO2 was significantly higher in the RCHV during the course of exercise (pH = 7.24 and 7.29; Paco2 = 56 and 51 mmHg; V̇co2 = 156 and 135 ml/kg x min in RCHV and NV, respectively, at highest workload). The Pao2 predicted from the V̇A/Q̇ distribution was higher than actually measured in blood during heavy exercise which may suggest a certain diffusion limitation over the alveolar‐capillary membranes in both groups but there was no difference between the 2 groups. The more pronounced hypoxaemia observed in RCHV trotters was mainly caused by increased V̇A/Q̇ mismatch expressed as a significantly increased log SDQ (0.78 and 0.45 in RCHV and NV, respectively, at highest workload).
Pulmonary vascular resistance of horses decreases with moderate exercise and remains unchanged as workload is increased to maximal exercise
Authors: MANOHAR M. , GOETZ T. E. 
Published: June 2010

SummaryThis study was carried out to examine changes in pulmonary vascular resistance (PVR) induced by moderate and strenuous exercise; the objective being to understand why pulmonary artery blood pressure of exercising horses increases progressively as work intensity increases. Pulmonary arterial and wedge pressures (referenced at the point of the left shoulder) were determined simultaneously with cardiac output in 2 groups of healthy, sound, exercise‐trained horses. Horses inGroup 1(n = 8) were studied at rest and during exercise performed at 8 and 13 m/s; the latter workload eliciting maximal heart rate (mean ± s.e. 212 ± 3 beats/min). Horses inGroup 2(n = 7 Thoroughbreds) were studied at rest and during galloping at 14.5 m/s on 5% uphill grade, a workload which elicited maximal heart rate (217 ± 3 beats/min) and could not be sustained for >90 s. Pulmonary vascular resistance was calculated by dividing pulmonary perfusion pressure gradient (i.e. mean pulmonary arterial pressure minus mean pulmonary wedge pressure) with cardiac output Pulmonary arterial and wedge pressures, pulmonary perfusion pressure gradient and cardiac output increased significantly (P<.05) with exercise in both groups. There were no differences in PVR between the 2 groups of horses at rest InGroup 1horses PVR decreased significantly (P<.05) with exercise at 8 m/s, but further pulmonary vasodilat0ion did not occur as workload increased to 13 m/s. During exercise at 14.5 m/s on 5% grade, PVR ofGroup 2horses also decreased significantly and was not different from values for 8 or 13 m/s inGroup 1horses. It is concluded that PVR reaches its nadir during moderate exercise, presumably due to upper limit of recruitment and distension having been reached. Therefore, in accordance with Ohm's law (P α Q × PVR), in going to higher workloads pulmonary blood flow (Q̇) remained the sole determinant of the rise in pulmonary arterial blood pressure (P). Our data also indicate that pulmonary artery wedge pressure is another variable that is important in determining the absolute value of pulmonary arterial blood pressure.
Feasibility of scintigraphy in exercise‐induced pulmonary haemorrhage detection and quantification: preliminary studies
Authors: VOTION DOMINIQUE M. , ROBERTS C. A. , MARLIN D. J. , LEKEUX P. M. 
Published: June 2010

SummaryWe hypothesised that scintigraphic imaging of the lungs following injection of 99mTc labelled red blood cells (99mTc‐RBC) in the exercising horse might enable exercise‐induced pulmonary haemorrhage (EIPH) quantification. Ideally, to favour detection of bleeding, circulating 99mTc‐RBC not involved in the haemorrhage should be removed from the circulation quickly. Altering RBC during labelling to stimulate splenic uptake of 99mTc‐RBC may encourage this.In order to investigate this hypothesis, 99mTc‐RBC distribution was followed for 1 h in 2 groups of horses. Group 1 was injected i.v., at rest, with radioactive nondenatured RBC (99mTc‐NDRBC); Group 2 received labelled RBC partly denatured by heating (99mTc‐HDRBC). In Group 2, splenic uptake was higher at all times and radioactivity in the lung was proportionally higher and decreased less quickly than in Group 1. Hence, the time‐consuming 99mTc‐HDRBC labelling technique did not demonstrate any advantage over the easier 99mTc‐NDRBC labelling procedure.Additionally, the feasibility of scintigraphic visualisation of a small amount of pulmonary bleeding was confirmed with the following trial: using an endoscope, a radioactive solution mimicking 50 ml of bleeding was deposited at the usual site of EIPH in a live horse. The radioactivity recorded in that area was compared to the one obtained in the same region in Group 1 and 2. The activity measured 20 min post endoscopy corresponded to 33% of the activity obtained in Group 1 vs. 8% in Group 2 at that timing. Once again, there was no advantage of using 99mTc‐HDRBC vs. 99mTc‐NDRBC.These results demonstrated that small amounts of bleeding might potentially be detected with scintigraphy; they also suggest that the limiting factor for detecting small amounts of bleeding may be the level of lung background radioactivity.
Application of V200 values for evaluation of training effects in the young Thoroughbred under field conditions
Authors: KOBAYASHI M. , KURIBARA K. , AMADA A. 
Published: June 2010

SummaryThe purpose of this investigation was to study, under field conditions, the usefulness of an incremental exercise test to measure V200 (running velocity [V] at heart rate [HR] of 200 beats/min) for evaluation of training effects in the young Thoroughbred. Five to 112 two‐year‐old Thoroughbreds were used over 4 years to investigate the correlation between HR and V, the influence of the track and rider's weight to V200, reproducibility of V200 and the changes of V200 as training progresses. The high correlation coefficient between HR and V, and V200 were obtained in horses that exercised smoothly during gait changes and had acceleration during the canter in relaxed and nonexcitable states. The reproducibility of V200 as statistically significant providing the conditions were constant. Furthermore, the regression lines between HR and V gradually declined in parallel as training progressed. The average V200 in 2‐year‐old Thoroughbreds significantly increased from 623 ± 55 m/min to 691 ± 64 m/min after 5 months of training (P<.05). We concluded that V200 could easily be measured, that it was useful in evaluating treatment effect and that practical application under field conditions was possible.
EMG activity of the muscles of the neck and forelimbs during different forms of locomotion
Authors: TOKURIKI M. , OHTSUKI R. , KAl M. , HIRAGA A. , OKI H. , MIYAHARA Y. , AOKI O. 
Published: June 2010

SummaryWe recorded the electromyographic (EMG) activity of 7 skeletal muscles in the forequarters and 1 in the hindquarters of 6 Thoroughbred horses during overground walking, swimming in a circular pool, and walking and trotting in a water treadmill. Bipolar fine wire electrodes were inserted into the muscles and the EMG signals were recorded using a telemetric system. Thespleniusexhibited tonic EMG activity during swimming. Thebrachiocephalicsshowed its highest intensity during swimming followed by the walk and trot in the water treadmill and then walking overground. Thetriceps brachii caput longumhad a similar activity pattern to thebrachiocephalicus.Thebrachialisshowed only weak EMG activity in all 3 types of locomotion. Theextensor digitorum communishad higher intensity of EMG activity in the walk in the water treadmill than in other kinds of locomotion. Theflexor digitorum profundusexhibited the most intense EMG activity during swimming. These results indicated that swimming evoked strong EMG activity in the antigravity muscles in spite of reduced gravitational force. Walking in the water treadmill may require more intensified EMG activity of the forelimb than the trot in the same treadmill.
Chronological changes in superoxide‐scavenging ability and lipid peroxide concentration of equine serum due to stress from exercise and transport
Authors: ISHIDA N. , HOBO S. , TAKAHASHI T. , NANBO Y. , SATO F. , HASEGAWA T. , MUKOYAMA H. 
Published: June 2010

SummaryIt has been suggested that a variety of stresses on animals may accelerate their production of superoxide. Racehorses are considered to be exposed to substantial oxide stress due to transport and exercise for training and racing. To determine the effect of exercise and transport on racehorses in terms of superoxide and antioxidative ability, changes in the superoxide‐scavenging ability of equine serum were observed using electron spin resonance (ESR). Changes in the concentration of lipid peroxide, which is produced in equine serum by superoxide, were also examined.The analysis revealed that lipid peroxide concentrations increased as a result of stress from exercise and transport. On the other hand, the superoxide‐scavenging ability of equine serum showed a decline during transport, which is in sharp contrast to the increase seen immediately after a race due to the severe load exerted in exercise.
Factors affecting accumulation of lactate in red blood cells
Authors: VäIHKÖNEN LEENA K. , HYYPPä S. , PÖSÖ A. REETA 
Published: June 2010

SummaryIn horses, both the post exercise distribution of lactate between plasma and red blood cells (RBC) and the activity of lactate transporters on the RBC membrane vary widely between individuals. In this study, we investigated the effects of pH, time and temperature on lactate distributionin vitro, and compared thein vitroactivity of lactate transporters with the accumulation of lactate into RBCin vivo.To accomplish this, we took venous blood samples at rest and after trotting races. The post exercise accumulation of lactate into RBC was shown to depend on the activity of lactate transporters. The results,in vitro, also indicate that pH, incubation time and temperature influence the activity of lactate transporters and the accumulation of lactate into RBC, underscoring the fact that in practice it is important to standardise the measurement conditions of lactate. These results support the view that whole blood lactate concentrations should be measured in estimating the accumulation of lactate from exercising muscles into the blood, because the effect of blood pH, temperature, time to centrifugation of the sample and also interindividual variation in lactate transport into RBC are therefore minimised.
Comparison of exercise tests in French trotters under training track, racetrack and treadmill conditions
Authors: COUROUCÉ ANNE , GEFFROY O. , BARREY E. , AUVINET B. , ROSE R. J. 
Published: June 2010

SummaryStandardised exercise tests were performed at 2 different tracks and on an uninclined treadmill during the same week to determine the influence of exercise surface on different measured variables such as heart rate (HR), blood lactate concentration, packed cell volume, stride frequency, stride length, gait symmetry and regularity and on different derived physiological variables such as the speed at a HR of 200 beats/min (V200), the speed at a blood lactate concentration of 4 mmol/l (V4), the speed at a maximal HR (VHRmax). Five French Trotters, age 3 years, in training for 3 months prior to the test, performed 3 exercise tests on a training track (Test 1), a racetrack (Test 2) and an uninclined treadmill (Test 3). Test 1 utilised 3 steps each of 3 min at speeds of 490, 560 and 630 m/niin. Tests 2 and 3 utilised the same speeds and a fourth step in which the horse was accelerated for 30 s to speed approaching maximal. No significant differences (P<.05) were found for the physiological and locomotor variables between the 2 tracks. In contrast, there was a significant difference (P<.05) for these variables between the tracks and the treadmill, horses showing lower heart rate and blood lactate response, reduced stride frequency and increased stride length and regularity on the uninclined treadmill. We concluded that this standardised exercise test was repeatable on various tracks even when the surface and geometry vary. In contrast, both physiological and locomotor variables were different when comparing the tracks with the uninclined treadmill.
Effect of forage intake on bodyweight and performance
Authors: ELLIS J. M. , HOLLANDS T. , ALLEN D. E. 
Published: June 2010

SummaryThe horse evolved to survive on rations high in forage. Many performance horses are fed rations containing reduced levels of forage, with a corresponding increase in concentrate supply. Such reductions in forage intake are widely established to be associated with a corresponding number of physiological and psychological adaptations. Therefore, the influence of forage intake on bodyweight (bwt) and performance was investigated. Four Thoroughbred‐type geldings in light to moderate work received 4 diets (100% forage [100H]; 80% forage:20% concentrate [80H]; 60% forage:40% concentrate [60H] and 50% forage:50% concentrate [50H]) in a 4 times 4 Latin‐square design. A submaximal standardised exercise test (SET) was performed for each diet. Rate of passage, bwt and water intakes were measured throughout the trial and maximum, recovery heart rates and postexercise rectal temperatures recorded for each SET. Mean ± s.e. bwt was significantly (P<0.001) higher for the 100H compared to the 50H ration (556.89 and 546.28 kg, respectively). Rate of passage of digesta was significantly (P<0.01) slower for the 100H compared to the 50H ration. Water intakes and SET maximum and 1 min recovery heart rates were significantly (P<0.05) higher (mean ± s.e. 44.72 and 39.07 ***l/day, 186 and 165 beats/min, and 105 and 96 beats/min, respectively) for 100H compared to the 50H diet. Post‐SET rectal temperatures tended to increase with increasing forage intakes, although these effects were not significant (mean 39.85 and 38.65°C for the 100H and 50H diets, respectively). In conclusion, forage intake has significant effects on equine bwt and submaximal performance and a compromise needs to be made between the potential detrimental effects of high forage intake on performance and the potential detrimental effects of low forage intake on equine welfare.
Does training affect mRNA transciption for cytokine production in circulating leucocytes?
Authors: COLAHAN P. T. , KOLLIAS‐BAKER C. , LEUTENEGGER C. M. , JONES J. H. 
Published: June 2010

SummaryPhysical exertion is a stimulus for the upregulation of cytokine production including IL‐1β, IL‐1ra, IL‐2, IL‐4, IL‐6, IL‐10 and TNF‐α in horses. To investigate that hypothesis, we initiated training of 5 stall‐rested Thoroughbreds. Blood samples were drawn before and weekly during training. The relative transcription of mRNA within the leucocytes was measured using real time TaqMan quantitative PCR.The training protocol was walking (3 min), trotting (3 min) and cantering/galloping (6 min) increasing in intensity weekly (6 to 12 m/s) and culminating in an intense exercise period. Comparisons of mRNA concentrations were made using a repeated measures ANOVA on ranks and a Student‐Newman‐Keuls pair‐wise multiple comparison (P<0.05).The training programme or intense exercise bout did not affect IL‐2, IL‐4, IL‐6 and IL‐10. IL1‐β and TNF‐α transcription increased on Day 23. TNF‐α peaked on Day 23 and IL1‐β on Day 30. Neither demonstrated a response to intense exercise. IL‐1ra decreased significantly on Day 9; rose significantly from Day 9 to Days 16 and 23; remained significantly elevated through Days 30 and 37 over Day 9, and rose very slightly after intense exercise on Day 56.Alterations in leukocyte cytokine responses may influence susceptibility to infectious disease, metabolic responses to exercise or exercised induced syndromes.
Effect of an endurance race on muscle amino acids, pro‐ and macroglycogen and triglycerides
Authors: ESSÉN‐GUSTAVSSON B. , JENSEN‐WAERN M. 
Published: June 2010

SummaryGlycogenolysis and lipolysis are essential for energy production in muscle during prolonged exercise but less is known about the role of amino acid metabolism. The aim was to study the effect of an endurance race on pro‐ and macroglycogen, triglycerides and amino acid concentrations in muscle and on selected blood parameters, especially the amino acid response in the blood during the recovery phase.Seven endurance‐trained horses completed a race covering 100–120 km. Blood samples were collected one day before the race, after the finish and 1 and 8 days after the race. Needle biopsy specimens from the gluteus medius muscle were taken on completion of the race and 8 days postrace.The pro‐ and macroglycogen concentrations were lower and most amino acid concentrations were higher in the muscle after the finish of the race, than 8 days postrace, whereas the triglyceride concentrations did not differ. The concentrations of several amino acids in serum were higher during the recovery phase than before the race. The observed changes suggest that an endurance race influences amino acid metabolism and a net protein degradation may occur that persists during the recovery phase. Furthermore, the results suggest that macroglycogen is utilised to a greater extent than proglycogen during an endurance race. Further research is needed concerning amino acid metabolism during an endurance race as it seems to play an important role both for performance and recovery after exercise.
Dorsal metacarpal cortex ultrasound speed and bone size and shape
Authors: DAVIES H. M. S. 
Published: June 2010

SummaryIn Thoroughbred racehorses, the dorsal cortex (DC) of the third metacarpal bone (MC3) enlarges when horses are first exposed to fast exercise speeds. It is now possible to measure ultrasound speed through 3 to 5 mm depths of bone around the bone shaft using Sunlight Medical's ‘Omnisense’ machine. The aim of this experiment was to determine whether the ultrasound speed measured in the surface 3–5 mm of the midshaft dorsal cortex of MC3 could be related directly to the midshaft shape and size of the MC3s of young Thoroughbred racehorses at the same stage of training. Sixteen 2‐year‐old and sixteen 3 to 6‐year‐old racehorses, exercising at racing speed at the same training stable, had their ultrasound speed measured and were radiographed to measure their MC3 midshaft size (width of DC) and shape ([DC/palmar cortex] x [{DC+palmar cortex}/medulla widths]).There were significant linear relationships between ultrasound speed and radiographic bone size and shape measurements. The faster ultrasound speeds were associated with bones that were both absolutely and proportionately thinner in the dorsal cortex in both groups of racehorses. The measurement of ultrasound speed with the Sunlight Omnisense machine should allow more detailed and accurate predictions to be made for responses of the bone to exercise in the midshaft of MC3 than is possible using radiographic size and shape measurements alone. This should make it possible to predict, for example, how soon after a change in bone shape a specific horse can race with minimal risk of damage to the newly‐forming bone surface.
Influence of draw reins on ground reaction forces at the trot
Authors: ROEPSTORFF L. , JOHNSTON C. , DREVEMO S. , GUSTÅS P. 
Published: June 2010

SummaryAccording to riding texts, draw reins are supposed to support increased collection. This has not been measured objectively. Therefore, the objective of this study was to determine whether a horse ridden with draw reins would relatively increase weightbearing of the hindquarters while worked with the draw reins compared to a normal rein. Ground reaction forces were measured in 8 horses at the slow trot over a force plate in 3 different experimental setups: 1) riding with only a draw rein (DR); 2) riding with the combination of a normal and a draw rein (NR‐DR) and 3) riding with a normal rein (NR).Horses ridden with NR‐DR showed significant higher vertical impulse in the hindlimb compared to riding both with only DR and only NR. Several significant differences were also seen in the horizontal force. It is concluded that draw reins, when used correctly, together with a normal rein, achieve the desired result of shifting the weight of the horse caudally. This was not the case when the draw rein was used alone. It is important that trainers, as well as veterinarians, recommending draw reins in a rehabilitation programme, know about these possible effects.