bluuebunny/crossref_metadata_2025_split huggingface dataset:
Racing speeds of Quarter Horses, Thoroughbreds and Arabians
Authors: NIELSEN B. D. , TURNER K. K. , VENTURA B. A. , WOODWARD A. D. , O'CONNOR C. I. 
Published: June 2010

SummaryReasons for performing study:While Quarter Horses are recognised as the fastest breed of horse, direct comparisons to race times with other breeds can be misleading. Quarter Horse races begin when the starting gates open. Thoroughbred and Arabian races begin a short distance from the gates after horses have started running. This study compared speeds of these breeds as they accelerate from the starting gates and during the middle and end of races.Objectives:To compare racing speeds of the 3 breeds, and to compare speeds during various segments of the races.Methods:Video tapes of races were obtained from a local track. The various race segments were viewed and the winning horse timed by 5 individuals. Fastest and slowest times were removed and the 3 remaining times averaged.Results:Quarter Horses averaged faster speeds than Thoroughbreds even when Thoroughbreds were raced at a distance (402 m) similar to Quarter Horse races. Both breeds were substantially faster than Arabians. Quarter Horses racing 336 m or less gained speed in each segment of the race while Arabians and Thoroughbreds racing 1006 m ran fastest during the middle of the race and had decreased their speed in the final segment of the race.Conclusions:Despite similar race times reported for 402 m, Quarter Horses averaged faster speeds than Thoroughbreds when timed from a standing start. In short races, both breeds accelerate throughout the race. Arabians, despite being known for endurance, had slowed by the end of the race.Potential relevance:This study demonstrates that Quarter Horses achieve faster racing speeds than do other breeds. It also reveals a potential flaw in race‐riding strategy as a more consistent pace throughout the Arabian and longer Thoroughbred races may be more efficient and result in a faster overall race time.
Utilisation of the time constant calculated from heart rate recovery after exercise for evaluation of autonomic activity in horses
Authors: HADA T. , MUKAI H. OHMURA. K. , ETO D. , TAKAHASHI T. , HIRAGA A. 
Published: June 2010

SummaryReasons for performing study:Heart rate (HR) recovery immediately after exercise is controlled by autonomic functions and the time constant (T) calculated from HR recovery is thought to be an index of parasympathetic activity in man.Objectives:To investigate whether it is possible to evaluate autonomic function using the time constant in horses.Methods:Five Thoroughbred horses were subjected to a standard exercise test. Following pre‐medication with saline, atropine and/or propranolol, the horses ran for 2.5 min at a speed of 8 m/sec at a 10% incline and T was calculated from HR after the exercise. Secondly, 7 Thoroughbred horses were then trained for 11 weeks and T and maximal oxygen uptake (VO2max) measured at intervals of 1 or 2 weeks. In 6 horses, T with atropine pre‐medication was also measured before and after the whole training period. Furthermore, the HR variability at rest was evaluated by power spectral analysis at intervals of 3 or 4 weeks.Results:Time constant was increased by atropine and/or propranolol pre‐medication, decreased with the progress of training and inversely correlated with VO2maxduring training (r = 0.43, P<0.005). Parasympathetic blockade significantly decreased T only after and not before, the training; however, T was lower in post training than in pre‐training, irrespective of parasympathetic blockade. On the other hand, parasympathetic activity at rest was attenuated and sympathetic activity became predominant following the training.Conclusion:Heart rate recovery is affected by sympathetic withdrawal and parasympathetic reactivation in horses and suggests that physical training hastened HR recovery by improving the parasympathetic function after exercise with aerobic capacity. However, the effects of other factors need to be considered because the training effect appeared on T even under parasympathetic blockade. The parasympathetic activity at rest is in contrast to that after exercise, suggesting that T does not reflect parasympathetic activity at rest.Potential relevance:If demonstrated how HR recovery is controlled after exercise, its analysis will be important in the evaluation of physical fitness in horses.
An echocardiographic and auscultation study of right heart responses to training in young National Hunt Thoroughbred horses
Authors: LIGHTFOOT G. , JOSE‐CUNILLERAS E. , ROGERS K. , NEWTON J. R. , YOUNG L.E. 
Published: June 2010

SummaryReasons for performing study:There are few data available to determine the effect of training on cardiac valve function.Objectives:To investigate the effect of commercial race training on right ventricular (RV) and tricuspid valve function in an untrained group of National Hunt Thoroughbreds (TB).Material and methods:Cardiac auscultation, guided M‐mode echocardiography of the RV, and colour flow Doppler (CFD) tricuspid valve and right atrium were performed in 90 TB horses (age 2–7 years) 1998–2003. Forty horses were examined at least once and 48 horses were examined on at least 2 occasions. Examinations were then classified as: i) before commencement of race training, ii) after cantering exercise had been sustained for a period of 8–12 weeks and iii) at full race fitness. Tricuspid valve regurgitation (TR) murmurs were graded on a 1–6 scale and CFD echocardiography TR signals were graded on a 1–9 scale. Right ventricular internal diameter (RVID) in diastole and systole (RVIDdand RVIDs) was measured by guided M‐mode. Associations between continuous RVID and TR measures and explanatory covariates of weight, age, heart rate, yard and stage of training were examined using general linear mixed models with horse‐level random effects.Results:On average, RVIDdand RVIDsincreased by 0.08 and 0.1 cm, respectively, per year increase in age (P=0.1 and 0.02) and by 0.3 and 0.4 cm, respectively between pre‐training and race fitness (P = 0.07 and 0.005). Tricuspid regurgitation score by colour flow Doppler increased by 0.6/year with age (P<0.0001) and by 1.8 between pre‐training and race fitness (P< 0.0001). No significant associations were found between any outcomes and weight, heart rate and training yard. Due to the high level of co‐linearity between age and training, multivariable models including both terms were not interpretable.Conclusions and clinical relevance:Athletic training of horses exerts independent effects on both severity and prevalence of tricuspid valve incompetence. This effect should therefore be taken into account when examinations are performed. Dimensions of RV increase with age and training in TB horses in a manner that appears to be similar to that of the LV.
Effect of light exercise on valvular regurgitation in Standardbred trotters
Authors: BUHL R. , ERSBØLL A. K. 
Published: June 2010

SummaryReasons for performing study:Although valvular regurgitation is diagnosed frequently by colour Doppler echocardiography in racehorses at rest, there is currently no information about the effect of exercise on valvular regurgitation.Objectives:To investigate the effect of light exercise on valvular regurgitation in a population of trotters.Methods:Standardbred trotters (n = 73) were examined by resting auscultation and echocardiography, of which 50 fullfilled the criteria of the study. Of these, 4 had reduced performance according to the trainers and were not included in the statistical analyses. Horses that showed valvular regurgitations diagnosed by colour Doppler echocardiography at rest, were light exercised and the regurgitant valves were then re‐examined by colour Doppler echocardiography.Results:Of the 46 horses, 41 (89%) had one or more valvular regurgitations at rest with tricuspid regurgitation present in 83% of horses, mitral regurgitation 46%, pulmonary regurgitation 37% and aortic regurgitation 57%. After exercise, one or more valvular regurgitation persisted for 23 of the 41 horses (56%). The regurgitation decreased significantly for mitral, pulmonary and aortic valves; the mitral regurgitation persisted for 21% of the horses, pulmonary regurgitation persisted for 6% and aortic regurgitation persisted after exercise for 23% with regurgitation diagnosed at rest. Half of those with tricuspid regurgitation at rest still had tricuspid regurgitation after exercise.Conclusions:The results of this study showed that the majority of small valvular regurgitations disappear after light exercise. However, the severity of tricuspid regurgitation increased in 4 horses. Furthermore, these horses were not performing satisfactorily according to the trainers.Potential relevance:Studies in man have shown that severity after exercise suggests pathological regurgitation. The present study indicates that echocardiographic examination of valvular regurgitation after exercise might be a relevant examination in horses. However, more studies are needed to evaluate the effect of strenuous exercise on valvular regurgitation in horses.
Right ventricular pressure dynamics and stress echocardiography in pharmacological and exercise stress testing
Authors: DURANDO M. M. , SLACK J. , REEF V. B. , BIRKS E. K. 
Published: June 2010

SummaryReasons for performing study:There is interest in using pharmacological stress testing (PST) as a substitute for exercise stress testing (EST) to evaluate cardiac function in horses.Obectives:To compare the effect of PST and EST on right ventricular pressure dynamics and stress echocardiography.Methods:Five horses completed a PST and EST in a randomised crossover design. High fidelity pressure transducers were placed in the right ventricle. Continuous pressure signals were digitally collected and stored, and dP/dtmax, dP/dtminand tau calculated from these measurements. ECGs were recorded continuously for 20 h. Echocardiography was performed prior to EST and PST, during and after PST, and immediately post EST. Plasma cardiac troponin I concentrations were measured pre‐ and 3–4 h post stress testing. For PST, 5 μg/kg bwt glycopyrrolate i.v. followed after 10 min by 5 μg/kg bwt/min dobutamine infusion over 10 min was given. EST consisted of a 2 min gallop at 110% speed required to elicit VO2max.Results:Both EST and PST resulted in a significant increase in right‐ventricular dP/dtmaxand dP/dtminover baseline (P<0.05) and a significant decrease in tau compared with baseline (P<0.05). EST dP/dtmaxand dP/dtminwere significantly greater than PST dP/dtmaxand dP/dtmin(P<0.05) and EST tau was significantly less than PST tau (P<0.05). Two minutes post EST and 5 min post PST dP/dtmaxwere not significantly different, but were significantly less than end‐EST and during PST. Tau was also not significantly different between post EST and post PST, but was significantly decreased end‐EST compared with during PST. FS were not significantly different between PST and post EST, but during PST and post EST all FS were significantly higher than baseline. Cardiac troponin I concentrations were significantly elevated post PST and were greater than post EST. The clinical relevance of this is unknown.Conclusions:PST had a similar, although less marked effect on the cardiac parameters related to right‐ventricular pressure dynamics and a similar effect on echocardiography as exercise stress testing.Potential relevance:PST deserves further evaluation in normal horses and those with cardiac disease, and may be complementary to EST to better identify exercise‐induced cardiac dysfunction.
Associations between exercise‐induced pulmonary haemorrhage, right ventricular dimensions and atrioventricular valve regurgitation in conditioned National Hunt racehorses
Authors: YOUNG L. E. , HELWEGEN M. M. G. H. J. , ROGERS K. , KEARNS L. , SCHREIBER C. , WOOD J. L. N. 
Published: June 2010

SummaryReasons for performing study:Exercise‐induced pulmonary haemorrhage (EIPH) and tricuspid (TR) and mitral valve regurgitation (MR) are conditions with high prevalence in conditioned Thoroughbreds. Stress failure of pulmonary capillaries, leading to EIPH, is most likely when pulmonary vascular pressure is increased, and mitral regurgitation can result in pulmonary venous hypertension.Hypothesis:There might be an association between MR and EIPH and the right ventricle (RV) of horses known to suffer repeated episodes of EIPH, as their hearts would be subject to higher pulmonary vascular pressures and cardiac output during training and hence increased RV afterload and preload.Methods:An echocardiographic and auscultation study was conducted in 121 race‐fit National Hunt Thoroughbreds. Cardiac auscultation and echocardiography were performed. A guided M‐mode image of the RV just below the tricuspid valve was obtained from a right parasternal location and colour flow Doppler (CFD) used to interrogate the tricuspid valve and right atrium. The mitral valve was similarly examined from the left hemithorax. Severity of TR and MR by CFD was graded. Binary data on EIPH, based on whether the horse was perceived to have a clinically significant problem with EIPH, were determined retrospectively for each horse by the horses' primary care veterinary surgeon from medical and other records. Data were analysed using a standard logistic regression analysis approach.Results:EIPH was significantly and positively associated with the systolic and diastolic dimensions of the RV (P=0.017 and 0.011 respectively) and this association was not sensitive to the effects of age or weight. There were no significant associations between EIPH and TR or MR by auscultation or CFD (TR: auscultation P=0.1; CFD P=0.2 and MR: auscultation P=0.07; CFD P = 0.37).Conclusions and clinical relevance:This study was limited by the method used to classify EIPH, but there was no association between EIPH and horse age, weight, TR or MR in this population of Thoroughbreds. Nevertheless, RV internal dimension was greater in horses obviously affected by EIPH, suggesting that factors resulting in EIPH may directly or indirectly affect RV remodelling in athletic horses.
Effect of repeated exercise and recovery on heart rate variability in elite trotting horses during high intensity interval training
Authors: COTTIN F. , BARREY E. , LOPES P. , BILLAT V. 
Published: June 2010

SummaryReasons for performing study:Interval training is a commonly used training method for trotting horses. In addition, trainers are provided with efficient and inexpensive heart rate monitor devices for the management of training.Hypothesis:Since the high frequency (HF) frequency peak (fHF) of heart rate variability (HRV) corresponds to the breathing frequency in combination with stride frequency during trotting, it is hypothesised that modifications of breathing and stride frequencies induced by repeated exercise could be detected fromfHF.Methods:RR interval time series of 7 trotting horses were recorded during an interval training session. Interval training was made up of 5 successive 800 m high‐velocity trotting runs (H1, H2…H5) separated by 1 min recovery bouts at low speed (R1, R2.R5). Fast Fourier transform (FFT) and Poincaré plot analysis techniques were applied to RR series.Results:Repeated exercise had significant effects on HRV components during interval training. Despite constant trotting velocities during high‐speed and recovery, repetition induced a decrease in mean RR interval (H1: 295 ± 19 vs. H5: 283 ± 15 msec, P<0.05) and in the root mean square of successive differences in RR series (RMSSD; H1: 6.31 ± 1.28 vs. H5: 5.31 ± 1.31 msec, P<0.05). Furthermore, high‐speed and recovery repetitions induced an increase infHF (H1: 1.37 ± 0.35 vs. H5: 1.62 ± 0.40 Hz and R1: 0.22 ± 0.02 vs. R4: 0.64 ± 0.38 Hz, P<0.05). Hence, recovery induced a decrease in the s.d. of the successive RR series (SDRR; R3: 10.5 ± 3.96 vs. R5: 6.17 ± 2.65 msecs, P>0.05) and in the long term index of Poincaré plot (SD2; R1: 43.29 ± 28.90 vs. R5: 18.19 ± 9.35 msecs, P<0.05).Conclusions:The observed increase infHF during the interval training could be induced by alterations of the coupling between breathing and stride frequency linked to the emergence of fatigue. The decrease in SD2 and SDRR during successive recovery bouts could be linked with a deterioration of the recovery pattern.Potential relevance:HRV can provide breathing frequency data of Standardbreds during training without any respiratory device. Furthermore, HRV could provide useful makers of the emergence of fatigue states during training.
The effect of long‐term exercise on glucose metabolism and peripheral insulin sensitivity in Standardbred horses
Authors: de GRAAF‐ROELFSEMA E. , Van GINNEKEN M. E. , Van BREDA E. , WIJNBERG I. D. , KEIZER H. A. , Van der KOLK J. H. 
Published: June 2010

SummaryReasons for performing study:To study the possible long‐term effect of improved glucose tolerance in horses after long‐term training, as the impact of exercise training on glucose metabolism is still unclear in the equine species. It is not known whether there is a direct long‐term effect of training or if the measurable effect on glucose metabolism is the residual effect of the last exercise session.Objectives:To determine the chronic effect on glucose metabolism and peripheral insulin sensitivity of long‐term training in horses by use of the euglycaemic hyperinsulinaemic clamp technique.Methods:Eleven Standardbred horses were acclimatised to running on the high‐speed treadmill for 4 weeks (Phase 1) followed by training for 18 weeks with an alternating endurance (˜ 60% HRmax) high intensity training programme (˜ 80% HRmax) (Phase 2). Training frequency was 4 days/week. At the end of Phase 1, a euglycaemic hyperinsulinaemic clamp was performed 72 h after the last bout of exercise in all horses. At the end ofPhase 2, the horses were clamped 24 h or 72 h after the last bout of exercise.Results:Glucose metabolism rate did not change significantly after 18 weeks of training, measured 72 h after the last exercise bout (0.018 ± 0.009 and 0.022 ± 0.006 mmol/kg bwt/min, respectively). Peripheral insulin sensitivity also did not change significantly following training (7.6 ± 5.7 times 10−6and 8.0 ± 3.1 times 10−6, respectively). The same measurements 24 h after the last bout of exercise showed no significant differences.Conclusions:Results indicated that long‐term training in Standardbreds neither changed glucose metabolism or insulin sensitivity 72 h after the last bout of exercise.Potential relevance:The fact that the beneficial effect of increased insulin sensitivity after acute exercise diminishes quickly in horses and no long‐term effects on insulin sensitivity after chronic exercise have as yet been found in horses, implies that exercise should be performed on a regular basis in horses to retain the beneficial effect of improved insulin sensitivity.
Effects of short‐term training on insulin sensitivity and skeletal muscle glucose metabolism in Standardbred horses
Authors: STEWART‐HUNT L. , GEOR R. J. , McCUTCHEON L. J. 
Published: June 2010

SummaryReasons for performing study:Increased insulin sensitivity occurs after a period of exercise training, but the mechanisms underlying this training‐associated increase in insulin action have not been investigated.Objective:To examine the effects of short‐term endurance training (7 consecutive days) and a subsequent period of inactivity (5 days) on whole body insulin sensitivity and GLUT‐4 protein and the activities of glycogen synthase (GS) and hexokinase (HK) in skeletal muscle. It was hypothesised that training would increase insulin sensitivity in association with increased GLUT‐4 protein and activities of GS and HK, but that these changes would be transient, returning to baseline after 5 days of inactivity.Methods:Seven mature Standardbred horses completed training consisting of 7 consecutive days of 45 min of treadmill exercise at a speed that elicited 55% of pretraining maximal aerobic capacity (VO2peak). Insulin sensitivity was determined by rate of glucose disposal (M) during the last 60 min of a 120 min euglycaemic‐hyperinsulinaemic clamp (EHC) performed before (‐2 days) and at 1 and 6 days following training. VO2peakwas measured before (UT) and after (TR) training and the period of inactivity (IA).Results:Training resulted in a 9% increase in mean VO2peak(P<0.05) that was maintained following inactivity (IA). Mean M values were more than 2‐fold higher (P<0.05) in TR than in UT. Mean M was also higher (P<0.05) in IA when compared to UT. GLUT‐4 protien abundancewas more than 10‐fold higher in TR and IA (P<0.001) than in UT. Pre‐EHC GS activity and GS fractional velocity were increased (P<0.05) in TR when compared to UT and IA. Pre‐EHC HK activity was increased (P<0.05) in IA when compared to UT and TR. Muscle glycogen was 66% lower (P<0.05) in TR than in UT and IA.Conclusions:Short‐term training resulted in increases in whole body insulin sensitivity, and GLUT‐4 protein content and glycogen synthase activity in skeletal muscle. The enhancements in insulin sensitivity, GLUT‐4 protein and glycogen synthase activity were still evident after 5 days of inactivity.Potential relevance:Insulin resistance in equids has been associated with obesity and predisposition to laminitis. Regular physical activity may mitigate risk of these conditions via enhancement of insulin sensitivity and/or control of bodyweight.
Frusemide results in an extracellular to intracellular fluid shift in horses
Authors: FORRO M. , LINDINGER M. I. 
Published: June 2010

SummaryReasons for performing study:Frusemide (Lasix) is commonly used diuretic in horse racing and equine clinical practice. While pharmacology, pharmacodynamics, renal and haematological effects of frusemide have been studied in horses, its effects on the distribution of fluid within the horse remain unknown.Objective:To quantify the effects of frusemide on extracellular and intracellular fluid shifts.Methods:Horses were infused with 1 mg/kg body mass (n=7) or 2 mg/kg (n = 9) i.v. frusemide. Total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) were measured using D2O, NaSCN and Evans blue dilution. Change in ECFV was assessed from the change in plasma [protein] and from repeated infusion/dilution of NaSCN.Results:Frusemide resulted in a 0.020 ± 0.002 1/kg decrease in TBW within 120 min. At 120 min after frusemide infusion the ECFV losses were nearly double the TBW losses, therefore ECFV loss in excess of TBW loss is seen as an increase in ICFV.Conclusions:Frusemide resulted in a net shift of fluid (electrolytes and water) from the extracellular to intracellular fluid compartment.Potential relevance:The fluid shifts that occur within horses administered frusemide has not previously been characterised. The intracellular shift of fluid is of performance and clinical significance.