bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiorespiratory measurements and indices of oxidative stress in exercising COPD horses
Authors: ART TATIANA , KIRSCHVINK NATHALIE , SMITH NICOLA , VOTION DOMINQUE , LEKEUX P. 
Published: June 2010

SummaryThe effect of a COPD crisis on arterial blood gases, heart rate, lactate and indices of oxidative stress were investigated before, during and 1 h after a ‘run up to fatigue’ in 6 COPD horses. They were investigated twice, randomly: once in acute crisis (C) and once in clinical remission (R). Arterial and mixed venous blood samples were collected and analysed for partial pressures in O2 and CO2. The mixed venous blood was also analysed for plasma lactate (LA) and packed cell volume (PCV), as well as for indices of oxidative stress, i.e. reduced glutathione, glutathione disulphide, glutathione redox ratio (GRR) and lipid hydroperoxides (LPH). The exercise test was an effort of increasing intensity on a treadmill at 0% slope, which was stopped when the horses showed signs of exhaustion. Their performance was evaluated by the number of steps and the running time in the last step. Heart rate was monitored continuously during the test Blood sampling was performed before, just after and 1 h after the end of the test.The COPD crisis significantly reduced the time to fatigue. However, despite the fact that the exercise intensity and length were lower, peak HR and peak LA were similar in C and R, while arterial hypoxaemia and hypercapnia, and PCV were significantly higher in C, indicating a higher physiological stress in this condition. By contrast, the oxidative stress seemed to be higher in R than in C as suggested by the fact that, 1 h after exercise, GRR and LPH were significantly increased with regards to their pre‐exercise values in R and not in C. The fact that exercise did not induce an oxidative stress in C could be partly related to (1) the lower exercise intensity reached by the horses, and (2) to the more severe hypoxaemia experienced in this condition.In conclusion, COPD horses in acute crisis show a significant decrease in performance. The reasons for this exercise intolerance remain unclear, but do not appear to be related to any increase of the oxidative stress in C.
Changes in left ventricular dynamics during graded exercise
Authors: HIRAGA A. , HOBO S. , BIRKS E. K. , TAKAHASHI T. , HADA T. , SMITH B. L. , CARR E. A. , PASCOE J. R. , JONES J. H. 
Published: June 2010

SummaryThree mature Thoroughbred horses were prepared surgically with ultrasonic sonomicrometer crystals affixed to their ventricular pericardia. Signals from crystals recorded dimensions of axes across the left ventricle. Cubic algorithms were fitted to dimensional data to generate volume estimates that matched stroke volumes simultaneously measured using the Fick principle. As horses stood at rest or exercised at various intensities (approx 7, 12, 24, 47 and 100% maximal rate of O2consumption [V̇o2max]), left ventricular dimensions were recorded and 20 consecutive diastolic and systolic volumes calculated. Although Fick estimates detected no difference in stroke volume at different exercise intensities, sonomicrometer measurements of stroke volume were significantly lower at rest and higher at V̇o2max. These differences mirrored changes in end‐diastolic volume, although end‐systolic volume did not change. At all exercise intensities, stroke volume was most variable and end‐diastolic volume the least. The pattern conforms to the Frank‐Starling mechanism, and indicates that at high exercise intensities ventricular myocytes generate high pressures with higher myocardial wall stress due to the increased size of the chamber.
Cardiac output measurements using sonomicrometer crystals on the left ventricle at rest and exercise
Authors: PASCOE J. R. , HIRAGA A. , HOBO S. , BIRKS E. K. , YARBROUGH T. B. , TAKAHASHI T. , HADA T. , AIDA H. , STEFFEY E. P. , JONES J. H. 
Published: June 2010

SummaryEight horses were fitted surgically with 8 ultrasonic sonomicrometer crystals each attached to their left ventricular pericardia and a left atrial catheter. Three horses returned to treadmill performance with a maximum rate of oxygen consumption similar to their presurgical values. These horses were evaluated to determine how well sonomicrometer estimates of cardiac output agreed with those obtained by a steady‐state method, the Fick principle. Variance between the 2 was similar to the coefficient of variation (approximately 12.5%) of the Fick estimates. We conclude that left ventricular sonomicrometer measurements in horses appear to give a reasonable estimate of ventricular dimensions and can, therefore, be used potentially to evaluate such variables as diastolic flow.
Oral nitroglycerin paste did not lower pulmonary capillary pressure during treadmill exercise
Authors: HACKETT R. P. , DUCHARME N. G. , GLEED R. D. , ERB H. N. , MITCHELL L. M. , SODERHOLM L. V. 
Published: June 2010

SummaryWe hypothesised that 22.5 mg of oral nitroglycerin would cause pulmonary vasodilation and therefore decrease pulmonary capillary pressure in horses during strenuous exercise. Six horses were assigned to exercise twice, once with no medication (control) and once with nitroglycerin (22.5 mg orally) in random order. Horses were exercised for 3 min each at 75, 90 and 100% of maximal heart rate (HRmax) with a 2 min period of walking between each period of exertion. Pulmonary artery and oesophageal pressures were recorded continuously. Subsequent analysis was carried out on the pulmonary arterial pressure signal with the oesophageal pressure subtracted, hence pulmonary vascular pressures reported in this paper approximate transmural pressures. Pulmonary arterial pressure, pulmonary arterial wedge pressure, pulmonary capillary pressure, heart rate and arterial blood gas tensions were determined for each level of exercise. Pulmonary arterial wedge and pulmonary capillary pressures were determined from the pulmonary artery waveform after dynamic occlusion of a branch of the pulmonary artery. The resulting decay in pulmonary artery pressure was submitted to an exponential curve fitting and the amplitude at the moment of occlusion on this curve was recorded as pulmonary capillary pressure. The effects of nitroglycerin on the various parameters were evaluated using a 3‐way ANOVA blocked on horse treatment, and exercise intensity, followed by Tukey's multiple comparison procedure. Resting pulmonary artery pressure decreased from mean ± s.e. 34.0 ± 5.5 mmHg to 24.0 ± 3.9 mmHg 5 min after administration of nitroglycerin (P<.05) but there were no significant effects on pulmonary capillary or wedge pressures. Nitroglycerin at this dose resulted in no significant differences in pulmonary artery, pulmonary capillary, and pulmonary wedge pressure, heart rate, arterial oxygen tension or arterial carbon dioxide tension at 75, 90 and 100% of HRmax. This dose of nitroglycerin does not appear significantly to protect the pulmonary vascular bed from exercise‐induced hypertension. These data do not support the use of this dose of oral nitroglycerin in the prevention of EIPH.
Influence of frusemide on dynamic cardiac variables during exercise
Authors: LANGSETMO INGRID , WEIGLE G. E. , ERICKSON H. H. , FEDDE M. R. 
Published: June 2010

SummaryExercising horses have extremely high right and left atrial pressures. Limitation in ventricular function (i.e. relaxation) may play a role in these high pressures. We studied relaxation characteristics of the right ventricular myocardium and the impact of frusemide (2.0 mg/kg bwt i.v.) on these characteristics in horses exercising at 8, 10, 12 and 14 m/s. Exercise tests were performed 4 h after administration of frusemide. Right ventricular (RV) pressure was analysed using Fast Fourier Transform techniques to remove non cardiac components of the pressure signal. Mean right atrial (RA) pressure increased with exercise and was significantly attenuated at all speeds by frusemide. RV maximum and minimum rates of pressure change with respect to time (RV+dP/dtmax, RV‐dP/dtmax) increased with exercise and RV relaxation time constant (RVτ) and time of RV relaxation from 65–20% of the difference between maximum and minimum ventricular pressure (Δ65–20) decreased with exercise. Frusemide produced no significant differences in +dP/dtmax, ‐dP/dtmax, RVτor Δ65–20 except at 12 m/s where RVτwas longer after frusemide (23.4 ms for frusemide vs. 19.7 ms for control). Significant reductions in stroke volume were seen at 8, 10 and 14 m/s after frusemide. These results suggest that the reduction of atrial pressure by frusemide is not due to changes in ventricular relaxation rate.
Effects of pre‐exercise frusemide administration and post exercise anaesthesia on cardiopulmonary and acid‐base parameters and blood and plasma volumes in horses exercised supramaximally to fatigue
Authors: KEEGAN R. D. , GREENE S. A. , BROWN J. A. , WEIL A. B. , BAYLY W. M. 
Published: June 2010

SummarySix horses were randomly assigned to receive either frusemide (F) (0.5 mg/kg i.v.) or an equivalent volume of saline (S) i.V., 4 h prior to treadmill exercise. Horses were instrumented to enable measurement of heart rate (HR), systolic (SAP), mean (MAP), and diastolic (DAP) carotid arterial pressures, pulmonary artery pressure (PAP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), blood gases, and cardiac output (CO). Plasma (PV) and blood volumes (BV) were measured using 2 injections of Evan's Blue dye. Baseline parameters were recorded while the horse stood quietly. Horses were then administered F or S. Four hours later, they were warmed up for 3 min at 4 m/s and then exercised to the point of fatigue at 115% V̇o2max. Horses were anaesthetised immediately following exercise by administration of detomidine (0.04 mg/kg bwt i.v.) followed 5 min later by tiletamine‐zolazepam (1.25 mg/kg bwt i.v.). After transporting the horse to a recovery stall, anaesthesia was maintained with isoflurane in 100% O2. Data were analysed using a 2‐way ANOVA with repeated measures withpost hocdifferences identified using the Student‐Newman‐Keul's procedure. Exercise was associated with increases in HR, SAP, MAP, DAP, PAP, CVP, TEMP, PCV, and BV, and decreases in PV, pH, arterial bicarbonate and base excess. Anaesthesia was associated with marked hypercapnia, a decrease in HR following detomidine administration, and persistent pulmonary hypertension despite carotid arterial pressure which returned to baseline. No effects attributable to F were identified at any time during the study.
Influence of training on autonomic nervous function in horses: evaluation by power spectral analysis of heart rate variability
Authors: KUWAHARA M. , HIRAGA A. , KAI M. , TSUBONE H. , SUGANO S. 
Published: June 2010

SummaryWe studied the influence of training on autonomic nervous function in the horse. For this purpose, Holter electrocardiogram (ECG) was recorded before and after training from 24 Thoroughbred horses (2‐year‐olds) and autonomic nervous function was evaluated by the power spectral analysis of heart rate (HR) variability. We obtained HR, low‐frequency (LF) power, high‐frequency (HF) power, and LF/HF ratio from recording. We set LF at 0.01–0.07 Hz and HF at 0.07–0.6 Hz. The HF power is thought to reflect primarily parasympathetic nervous function. Both the sympathetic and parasympathetic nervous systems have been shown to contribute to the LF power. The LF/HF ratio is considered as an index of the cardiac sympathovagal balance. Second degree atrioventricular blocks were found in the ECG of 3 and 5 horses before and after the training period, respectively. Ventricular premature depolarisations were detected in a horse after the training period. Heart rate decreased at night The lowest HR values had a tendency to appear in the early morning. Both the LF and HF power tended to be higher at night However, the LF/HF ratio was almost the same throughout the day. The HR was significantly decreased by training. Although the LF power and LF/HF ratio were significantly increased, the HF power was not changed by training. These results suggest that parasympathetic nervous activity may be fully activated even before training in this species.
The effect of supramaximal exercise on equine platelet function
Authors: KINGSTON JANENE K. , SAMPSON SARAH N. , BEARD LAURIE A. , MEYERS K. M. , SELLON DEBRA C. , BAYLY W. M. 
Published: June 2010

SummaryWhen blood is collected into sodium citrate in the proportion of 9 parts blood:1 part sodium citrate, the concentration of plasma sodium citrate in the sample will depend on the packed cell volume (PCV) of the blood sample. This difference in plasma sodium citrate concentration secondary to alterations in PCV significantly affects human platelet aggregation responses. Since horses attain a high PCV in response to high‐intensity exercise we investigated the effect of differences in sample plasma sodium citrate concentration on equine platelet aggregability. In addition, low molecular weight heparin (LMWH) was evaluated as an alternative anticoagulant for assessment of platelet aggregability during strenuous exercise in horses. Blood samples were collected pre‐exercise and at fatigue after supramaximal treadmill exercise into either 3.8% sodium citrate (9 parts blood:1 part sodium citrate) or 20 u LMWH/ ml of blood. Platelet aggregation responses to 1.25 μmol/l adenosine diphosphate (ADP) were measured via optical aggregometry. For samples collected into sodium citrate, aggregability was significantly less than pre‐exercise values in samples collected at fatigue and in pre‐exercise samples in which sodium citrate concentrations were adjusted to equal those in fatigue samples. However, samples collected into LMWH showed significantly increased platelet aggregability in samples collected at fatigue when compared to pre‐exercise samples. In conclusion, higher plasma sodium citrate concentration had a marked inhibitory effect on equine platelet aggregation responses. Low molecular weight heparin was a good alternative anticoagulant for assessment of equine platelet function and results indicate that equine platelet aggregability was enhanced in response to supramaximal exercise.
Plasma atrial natriuretic peptide during and after repeated exercise under heat exposure
Authors: KOKKONENt U.‐M. , HYYPPä S. , PÖSÖ A. REETA 
Published: June 2010

SummaryPlasma atrial natriuretic peptide (ANP) responses were studied in horses during and after a competition exercise test (CET) designed to simulate the endurance test of a 3‐day event and including testPhases A‐D.CET was repeated 5 times at 2 week intervals at mean temperature +28°C and relative humidity (RH) 58%. Heart rate (HR) was monitored during CET. After CET, the horses were rehydrated with isotonic glucose‐electrolyte solution or water. ANP, NH2‐terminal pro‐atrial natriuretic peptide (NT‐ANP), aldosterone, arginine vasoapressin (AVP) and plasma proteins (PP) were measured during CET and recovery. ANP rose with intensity and duration of exercise from 8 pmol/l to 15 pmol/l at a gallop (Phase B), remained elevated atPhases C‐X, and peaked (23 pmol/l) at a canter (Phase D). Thereafter, ANP decreased to the pre‐exercise level within 2.5 h irrespective of rehydration. Repeated exercise bouts failed to affect plasma ANP, although other adaptive changes occurred. No diurnal variation in plasma ANP appeared. In NT‐ANP, the most marked elevation occurred duringPhases C‐D.In contrast to ANP, the decrease was minor for 1 h after the canter. ANP did not correlate with AVP or HR. In conclusion, exerciseper seaffected equine plasma ANP but the possible effect of thermal stress could not be demonstrated. The differences between ANP and NT‐ANP responses indicate differences in their release or elimination and suggest that the cardiac prohormone cleavage may occur intracellularly or simultaneously with secretion, not in circulation.
Relationship between V̇O2max, heart score and echocardiographic measurements obtained at rest and immediately following maximal exercise in Thoroughbred horses
Authors: SAMPSON SARAH N. , TUCKER R. L. , BAYLY W. M. 
Published: June 2010

SummaryWe evaluated the relationships of heart score (HS) and echocardiographic measures to maximal oxygen consumption (V̇o2max), maximal cardiac output (Q̇max), and maximal stroke volume (SVmax). Six fit, mature Thoroughbred horses weighing (mean ± s.e.) 487 ± 11 kg were run 4 times on an inclined (10%) treadmill. Each run consisted of a 3 min warm‐up at 4 m/s followed by completion of an incremental exercise test in which each horse ran until V̇os2max was reached. Arterial and mixed venous blood was collected to determine arteriovenous oxygen content difference [C(a‐v)o2] in the last 15 s of exercise. An ATL HDI 3000 ultrasound system and a 3.5 MHz phased array transducer were used to make echocardiographic measurements before and within 2 min of run completion. Guided M‐mode echocardiographic measurements of left ventricular diameter (LVD), interventricular septal thickness (IVS) and left ventricular free wall thickness (LVFW) during diastole (D) and systole (S) were made from the right parasternal short axis view at the level of the chordae, and V̇o2 and C(a‐v)o2 were measured as the appropriate M‐mode view was recorded. Maximum heart rate (HRmax) was determined using a cardiotachometer, and HS was calculated on nonexercise days using the established technique. Maximum cardiac output and SVmax were calculated from the Fick equation and HRmax. Backward stepwise regression analysis was used to relate pre‐ and post exercise echocardiographic measurements and HS to V̇o2, Q̇, and SV at the time of measurement, and to V̇o2max, Q̇max, and SVmax. Pre‐ and post exercise LVDD appeared to be the most important variable in these equations. Mean pre‐exercise HR at the time of measurement was 54.7 ± 1.9 beats/min, while the mean post exercise rate was 111.7 ± 2.6 beats/min. The mean ± s.e. V̇o2max was 150.4 ± 13.2 ml/(kg.min). Heart score was not correlated with V̇o2max, Q̇max, or SVmax. There was no significant difference between pre‐ and post exercise measurements of LVD, IVSS, and LVFWS.
Should equine athletes commence training during skeletal development?: changes in tendon matrix associated with development, ageing, function and exercise
Authors: SMITH R. K. , BIRCH HELEN , PATTERSON‐KANE J. , FIRTH E. C. , WILLIAMS L. , CHERDCHUTHAM W. , WEEREN W. R. van , GOODSHIP A. E. 
Published: June 2010

SummaryIn human athletes, conditioning, training and competition are commenced before skeletal maturity. Yet in equine athletics, racing of young (age 2 years) horses remains contentious. Tendon injury persists as major causes of wastage in equine athletes. Minimising injury and associated welfare issues could involve a radical approach to the timing and implementation of conditioning and training. Tendons were examined from Thoroughbreds, Dutch Warmblood foals, working horses and also a group of wild horses to evaluate effects of age, function and exercise. Gross mechanical properties did not differ significantly with age or exercise, but showed a high variance within each group. Mechanical properties of tendon tissue showed significant differences as a function of age and location. The collagen fibril crimp angle and length showed a regional reduction in the central core with exercise and age, with a synergistic effect. Regional differences in collagen fibril diameter were seen in long‐term exercised older horses, but not in short‐term exercised, or younger, horses. The higher proportion of small fibrils in the central region of the long‐term exercised horses did not correlate with new collagen formation and therefore appear to result from disassembly of the larger diameter fibrils. Fibril diameter distributions were influenced by exercise regimens in the growing foal. Changes in molecular composition occurred in longer‐term exercise and older horses, in the centre of the tendon, with higher levels oftype IIIcollagen and changes in glycosaminoglycan (GAG) content. Cartilage Oligomeric Matrix Protein (COMP) levels also appear to be modulated by age, function and superimposition of exercise. These changes were all exacerbated with age and exercise, suggesting appropriate exercise in young horses may lead to a lower incidence of injury than in older horses. An hypothesis is advanced that immature tendon can respond to exercise while mature tendon has limited, if any, ability to do so. These findings support potentially controversial earlier conditioning and racing of younger, rather than older, equine athletes.
Kinematics of the equine back: flexion‐extension movements in sound trotting horses
Authors: AUDIGIÉ F. , POURCELOT P. , DEGUEURCE C. , DENOIX J. M. , GEIGER D. 
Published: June 2010

SummaryThis study was undertaken to evaluate the flexion‐extension movements of the back in a group of sound trotting horses. Using a 3‐D kinematic analysis system, 13 clinically sound horses fitted with 5 skin markers placed on the dorsal midline of their trunk were recorded while trotting on a track in the conditions of the routine lameness examination. These markers were used to calculate 3 back angles (thoracic, thoracolumbar and lumbosacral angle). These back angles were then filtered using Fourier series. To evaluate the repeatability of flexion‐extension movements, the intra‐ and inter‐individual variabilities were studied. The angle‐time diagrams showed that the equine back extended during the first part of each diagonal stance phase and flexed during the second part of each diagonal stance phase. The ranges of motion were less than 4° for the 3 back angles. The intra‐ and inter‐individual variability values of maximal extension and maximal flexion time points were similar and extremely low. This demonstrates the high repeatability of the temporal pattern of flexion‐extension movements of the back. Intra‐and inter‐individual variabilities of the range of motion showed that the back mobility varies more in‐between horses than between trials of the same horse. Compared with electromyographic activities of back muscles reported in the literature, flexion‐extension movements described in this study tend to show that, at a slow trot, trunk muscles act mainly to limit flexion‐extension movements of the back rather than to induce movements.
Influence of rough track surfaces on components of vertical forces in cantering Thoroughbred horses
Authors: KAI M. , TAKAHASHI T. , AOKI O. , OKI H. 
Published: June 2010

SummaryNo kinetic data are available to indicate the influence of a rough track surface and the resultant loss of footing on the components of hoof vertical forces. The aim of the present study was to evaluate the influence of rough track surfaces on the components of hoof vertical forces. Seven clinically sound 2‐year‐old Thoroughbred horses had instrumented shoes attached to both of the fore hooves to obtain the magnitudes of consecutive forces exerted in the hoof. All horses were cantered at approximately 10 m/s on straight tracks of smooth and rough surfaces of woodchip and dirt. The instrumented shoe indicated in real time 4 component forces acting on the hoof via 4 transducers positioned on the lateral and medial sides of the toe (LT, MT) and the heel (LH, MH). The peak vertical component forces of the heel were about twice that of the toe. The variances of the 4 components of peak vertical forces significantly increased on the rough track surface of both the woodchip (Leading: LH, MH and MT; Trailing: MH and LT) and dirt (Leading: LH and LT; Trailing: MH and MT) tracks. The trajectories of the position of the resultant force acting on the hoof also tended to increase the variance on rough track surfaces. Therefore, running on a rough track changes the vertical hoof forces and the balance of the resultant hoof forces. These results suggest a mechanism by which the rough track surfaces may influence the soundness of the horse.