bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coordination of equine forelimb motion during the gallop
Authors: DEUEL NANCY R. 
Published: June 2010

SummaryThe objective of this study was to compare shoulder, elbow and carpus rotations bilaterally during the gallop in an investigation of intralimb coordination of the foreleg during high‐speed asymmetrical quadrupedal locomotion. The motion patterns of the forelimb during the gallop stride were documented using high‐speed cinematography. The gallop stride characteristics of 4 Quarter Horse fillies, approximately 30 months of age, were examined. Horses were housed and fed together and received the same amount and type of limited training, and were all ridden with the same tack by one person. Both sides of each horse were filmed simultaneously (243 frames/s) while galloping individually along a 1.5 m‐wide track. Kinematic variables describing 29 strides (16 left lead, 13 right lead; mean velocity 13.1 m/s, stride frequency 2.60 strides/s, stride length 5.06 m) included temporal and linear measurements of the approximate centres of rotation of the shoulder, elbow and carpal joints; maximum and minimum relative angles and angular velocities of those joints; and maximum and minimum angles with respect to the horizon of the scapula, humerus, radius and metacarpus segments. In both forelimbs, hoof impact was followed sequentially by maximal carpal extension and maximal elbow extension in weightbearing during the stance phase. Hoof lift‐off was followed sequentially by maximal carpal flexion, maximal shoulder flexion, maximal elbow flexion and simultaneous shoulder maximal extension and an initial extension peak of carpus well prior to hoof impact. Temporal patterns of forelimb motion at the gallop appear to originate proximal to the elbow joint. Distal to the shoulder joint, basic motion patterns are remarkably similar on the leading and trailing sides of the body. A high degree of reciprocity in shoulder joint action was observed, a mechanism contributing to the energetic economy of the equine gallop.
Drop hammer tests of Scandinavian harness racetracks
Authors: DREVEMO S. , HJERTÉN G. , JOHNSTON C. 
Published: June 2010

SummaryDrop tests were carried out on 8 Scandinavian harness racetracks in order to evaluate their shock force attenuation properties. A drop hammer model was designed to simulate the hoof strike of the horse. The analysis comprised calculations for mean hardness index, impact time and energy loss which were correlated to ground composition parameters. The range of hardness, impact time and energy loss was 246–366 s−1, 7.6–13.2 ms and 74–95%, respectively at the inner lane of the track when the fallheight 0.6 m was used. The corresponding data for an outer lane were 225–392 s−1, 8.2–13.4 ms and 78–93%. The study showed significant differences in hardness, impact time and energy absorption between racetracks and between different test areas along the same course, with the outer lane usually being the harder. The drop height 1.5 m simulated a higher hoof landing velocity but gave similar results.It is suggested that impact force influence from the ground may be detrimental to horses and significant effort should be made in track construction and management. It is postulated that tracks with adequate cushioning are likely to prevent excessive shock loading and related musculo‐skeletal disorders in racehorses.
Biokinematic differences between riding horses judged as good and poor at the trot
Authors: HOLMSTRÖM M. , FREDRICSON I. , DREVEMO S. 
Published: June 2010

SummaryThe trotting gait of 4 approved Swedish Warmblood stallions with a mean gait score ≥8.67 (maximum score = 10) at official performance tests and 4 horses with poor gaits (mean gait score ≤6.5) was recorded by high speed film (250 frames/s). Angular patterns and hoof trajectories of the left fore and hind limbs were analysed and presented as mean and standard deviation curves. The good horses had longer stride duration (p<0.001) and larger positive diagonal advanced placement (p<0.01). The swing phase retraction in the forelimbs was longer in the good horses. The most important differences in the forelimb angular patterns were found in the elbow and carpal joint angles. They were considerably more flexed in the good horses at the beginning of the swing phase retraction. Larger decrease of the pelvis inclination, increase of the femur inclination and larger flexion of the hock and hind fetlock joints during the stance phase were correlated with high trot scores. This indicates that storage of elastic strain energy during the stance phase may be important for the elasticity, energy and propulsion in trot.
Stress and strain of equine tendons of the forelimb at failure
Authors: JANSEN MARGOT O. , SAVELBERG H. H. C. M. 
Published: June 2010

SummaryTendons of 12 equine forelimbs were loaded until failure using a drawbench. Preceding the tensile test, the cross sectional area was measured at the narrowest site of the tendon. Small beads were sutured to the tendons, as markers for length change measurement from photographs. During loading, photographs were taken at about 3 Hz and the load was recorded. The maximal strain was calculated by means of linear regression of length‐time data and extrapolation to the instant of failure according to the force‐time curve. Total failure of the superficial and deep digital flexor tendons, the distal check ligament and the suspensory ligament occurred at a strain (± sd) of respectively 10.9 (± 1.4), 9.5 (± 1.5), 12.4 (± 1.0) and 11.6 (± 1.4) % and at a stress of respectively 116 (± 21), 133 (± 14), 86 (± 11) and 70 (± 12)MPa.
Relationships between ground reaction force patterns and kinematics in the walking and trotting horse
Authors: MERKENS H. W. , SCHAMHARDT H. C. 
Published: June 2010

SummarySimultaneous recordings were made of retardatory‐propulsory horizontal (Fy) and vertical (Fz) ground reaction forces (GRF), and kinematics of the fetlock joint and the hoof‐sole with respect to the ground of the right forelimbs and hind limbs of 4 Dutch Warmbloods, at the walk and the trot. The impact oscillation visible in Fy and Fz is the same at the walk and trot, and differs between fore‐ and hind limbs. The angulation pattern of the fetlock joint does not follow the faster oscillations visible in the GRF. The change in the course of Fy and Fz in the final stage of ground contact is caused by onset of heel lift‐off.
Objective determination of ground contact of equine limbs at the walk and trot: comparison between ground reaction forces, accelerometer data and kinematics
Authors: SCHAMHARDT H. C. , MERKENS H. W. 
Published: June 2010

SummaryMutual timing relationships between hoof and fetlock joint kinematics, and objective criteria for ground contact based on accelerometry and ground reaction force measurements, were obtained for the right forelimbs and hind limbs of 4 horses at the walk and trot. Initial ground contact can be determined from accelerometer data or force plate signals, but not with sufficient accuracy from kinematics only. Prior to initial ground contact the hoof is positioned with the heels lowered in 3 of 4 horses. The change to foot flat occurs within 9 ms and can be identified unequivocally, provided that the hoof is visible and the recording equipment is sufficiently fast. Assuming that the onset of the stance phase is known, the end of the stance phase can be determined within 10% stride duration from the time at which the fetlock joint angle is identical to that at initial ground contact. Another criterion is the time at which the metacarpus or metatarsus and the first phalanx are aligned.
Review Article: Echocardiography
Authors: BONAGURA J. D. , BLISSITT KAREN J. 
Published: June 2010

SummaryEchocardiography encompasses a number of specific imaging techniques. The two‐dimensional (2‐D) echocardiogram is used to identify lesions of the heart and great vessels, assess myocardial function and provide a template for guiding contrast echocardiography, colour‐coded Doppler echocardiography and spectral Doppler studies. M‐mode echocardiography is used to measure cardiac size and ventricular function and can be combined with contrast or colour‐coded Doppler studies for accurate timing of flow events. Pulsed wave and continuous wave Doppler echocardiography display the direction and velocity of red blood cells within the heart and circulation. Continuous wave Doppler studies are used to calculate pressure gradients in the circulation. Any of the Doppler techniques can be used to identify abnormal or high velocity flow responsible for pathologic heart murmurs. Each Doppler format is complementary to the others: colour‐coded Doppler is used to screen large areas for flow disturbances; pulsed wave Doppler can pinpoint regions of abnormal flow; and continuous wave Doppler quantifies the maximal velocities of blood flow across cardiac lesions. Echocardiographic studies are very useful for the diagnosis and assessment of horses with cardiac murmurs, arrhythmias, and poor exercise performance. A number of cardiac disorders can be evaluated by echocardiography, including: cardiac malformation, valvular heart disease, cardiomyopathy, bacterial endocarditis, pericardial effusion, and congestive heart failure. When combined with a careful clinical examination, exercise evaluation and results of electrocardiography, the echocardiogram provides the best overall clinical assessment of the equine heart.
Echocardiographic measurements of cardiac dimensions and indices of cardiac function in normal adult Thoroughbred horses
Authors: PATTESON M. W. , GIBBS CHRISTINE , WOTTON P. R. , CRIPPS P. J. 
Published: June 2010

SummaryCardiac dimensions and indices of cardiac function were measured in 29 clinically normal adult Thoroughbreds (TB) which performed minimal exercise using guided M‐mode and two‐dimensional (2‐D) echocardiography, from a variety of image planes and measurement methods, and standardised imaging planes based on intracardiac anatomical landmarks. The different methods of measuring these variables were compared. The variables which were considered to be most valuable for quantitative echocardiography were measured in a further 9 horses.Comparable measurements of cardiac dimensions can be obtained from a variety of different imaging planes, using either 2‐D or guided M‐mode echocardiography from the left or right side of the chest, although differences in measurement methods must be taken into account. The results of this study give a useful range of dimensions and indices of cardiac function in normal adult TBs for comparison with those recorded from horses with suspected cardiac disease. Comparisons are only valid if there is meticulous attention to correct orientation of imaging planes with regard to internal landmarks and that comparable measurement locations and timing are used.
Echocardiographic measurements of cardiac dimensions in normal ponies and horses
Authors: SLATER J. D. , HERRTAGE M. E. 
Published: June 2010

SummaryEchocardiographic examinations were performed on 41 clinically normal small ponies, large ponies and horses. Using standardised two‐dimensional (2‐D) echocardiographic images to guide M‐mode studies, the interventricular septal thickness, left ventricular internal dimension and left ventricular wall in systole and diastole, and aortic diameter in diastole were measured. Normal values for these echocardiographic dimensions were obtained across a wide range of bodyweights. Although there was a trend for echocardiographic dimensions to increase with bodyweight across the whole range of animals examined, little or no linear correlation was found between dimensions and bodyweight within the small pony, large pony and horse groups.
Effects of sedation with detomidine hydrochloride on echocardiographic measurements of cardiac dimensions and indices of cardiac function in horses
Authors: PATTESON M. W. , GIBBS CHRISTINE , WOTTON P. R. , CRIPPS P. J. 
Published: June 2010

SummaryTwenty‐six horses were sedated with detomidine hydrochloride (Domosedan, SmithKline Beecham Animal Health, Tadworth, Surrey, UK) at a dose of 10 μg/kg bwt, administered i.v. Echocardiograms were recorded before and after sedation, measurements of cardiac dimensions were made and functional indices were calculated. The pre‐ and post sedation values were compared. No significant change was detected following sedation in the ejection time (ET), left ventricular dimension, left atrial diameter at the sinotubular junction at end‐systole or end‐diastole or at the sinus of Valsalva at end‐diastole. Sedation was found to result in a statistically significant increase in end‐systolic left ventricular diameter and internal area and aortic diameter measured at the sinus of Valsalva. Left ventricular free‐wall thickness and interventricular septal thickness at end‐systole, fractional shortening, fractional area change and heart rate were significantly reduced following sedation. A significant increase in pre‐ejection period (PEP), duration of electromechanical systole (EMS) and PEP/ET (ejection time) was detected.
Colour flow Doppler echocardiography in normal horses
Authors: BLISSITT KAREN J. , BONAGURA J. D. 
Published: June 2010

SummaryColour flow Doppler echocardiography is a technique that is used with two‐dimensional (2‐D) echocardiography to study blood flow patterns in the heart and blood vessels. This method was used to define normal flow patterns and to evaluate valvular function in 40 clinically normal Thoroughbred and Thoroughbred cross horses. Flow patterns from 10 standardised echocardiographic images were described in relation to anatomic landmarks and timing during the cardiac cycle. Consistent intracardiac flow patterns were identified in the normal horses. High velocity flow signals or regurgitant jets were recorded at the tricuspid (77.5%), mitral (67.5%), aortic (47.5%) and pulmonary valves (40%) in clinically normal horses. Most of these signals were transient, and many were associated with valve closure.This study demonstrates that colour flow Doppler echocardiography is a sensitive technique for the detection of intracardiac flow in horses. It will provide a basis by which to compare studies in horses suspected of having valvular heart disease.
Feasibility of transoesophageal echocardiography for evaluation of left ventricular performance in anaesthetised horses
Authors: YOUNG LESLEY E. , BLISSITT KAREN J. , CLUTTON R. E. , MOLONY V. , DARKE P. G. G. 
Published: June 2010

SummaryTransoesophageal Doppler echocardiography was performed in 7 Thoroughbred horses anaesthetised with halothane. The procedure was performed on 4 occasions under standard conditions. On one occasion dobutamine hydrochloride was infused at 4 μg/kg/min for 20 min. Recordings of aortic blood velocity, obtained using high pulsed repetition frequency Doppler echocardiography (HPRF), were used to derive maximum acceleration (dv/dtmax), maximum velocity (Vmax), left ventricular ejection time (ET), pre‐ejection period (PEP), velocity time integral (VTI) and cardiac output (CO).The coefficient of variation and 95% confidence intervals were narrower for the Doppler variables than for those obtained from cardiac catheterisation. For each horse the anaesthetic to anaesthetic repeatability of the Doppler indices of left ventricular function, exceeded that of maximum rate of rise of left ventricular pressure (LVdp/dtmax). The horse to horse variability was significant for heart rates Vmax, dv/dtmax, and VTI. After dobutamine infusion there were significant changes in all measured variables except heart rate, VTI and CO. The % change that occurred exceeded the predicted 95% confidence intervals for single measurements in all significantly affected variables. This suggests Doppler indices of cardiac performance may be useful to assess changes in haemodynamic function.Passage of the probe into the oesophagus was not associated with serious adverse effects. Mild serous nasal discharge was visible for up to 24 h after the horses recovered from anaesthesia. Mild nasal haemorrhage occurred on 5 occasions during probe insertion. It is concluded that transoesophageal Doppler echocardiography provides a minimally invasive, continuous method for monitoring left ventricular systolic performance in anaesthetised horses.
Review Article: Heart murmurs in horses: determining their significance with echocardiography
Authors: REEF VIRGINIA B. 
Published: June 2010

SummaryPhysiological flow murmurs occur frequently in horses and may be difficult to distinguish from murmurs associated with underlying cardiac disease. The significance of heart murmurs auscultated in horses is often difficult to determine if the horse is not exhibiting any clinical signs or if the signs, such as poor performance, are nonspecific. A complete echocardiographic examination (M‐mode, 2‐dimensional (2‐D) and Doppler) provides an objective assessment of the severity of the horse's underlying cardiac disease. Valvular regurgitation and ventricular septal defects (VSDs) occur frequently and may impair performance, result in the horse's premature demise or have no apparent effect on the horse's life expectancy or performance capabilities. The echocardiographic findings that are used to formulate a prognosis for longevity and performance in horses with valvular regurgitation include the abnormalities detected on the valve leaflets, degree of cardiac chamber enlargement, severity of the resultant volume overload, size of the regurgitant jet, and relative relationship of jet size to chamber size. The echocardiographic findings that are used to formulate a prognosis for horses with VSDs are the number, size and location of the defect(s), degree of left ventricular volume overload, maximal velocity and direction of shunt flow through the defect and the presence and severity of concurrent valvulus regurgitation. Knowledge of the natural progression of the common types of cardiovascular disease in horses, coupled with the echocardiographic findings, clinical history and owner's or trainer's expectations can help the veterinarian form en accurate prognosis for life and performance in horses with heart murmurs.
Colour flow Doppler echocardiography in horses with cardiac murmurs
Authors: BLISSITT KAREN J. , BONAGURA J. D. 
Published: June 2010

SummaryThirty‐two horses with cardiac murmurs typical of tricuspid, mitral and aortic regurgitation were studied using colour flow Doppler echocardiography. The dimensions and duration of any regurgitant signals, recorded at the cardiac valve suspected as being the site of origin of the murmur, were measured. Results were compared with flow signals described at the valves of normal horses (Blissitt and Bonagura 1995). Horses with murmurs suggestive of tricuspid (n=8) and aortic (n=8) regurgitation showed larger regurgitant signals at the tricuspid and aortic valves respectively, than has been reported in normal horses. Horses with murmurs suggestive of mitral regurgitation (n=8) had a regurgitant signal of longer duration than occurs in normal horses, but the jets were not larger. Comparison of two groups of horses with low and high grade murmurs of tricuspid regurgitation, showed that horses with louder murmurs had significantly longer jets of larger area than those with low grade murmurs. This study demonstrates that colour flow Doppler echocardiography is a sensitive technique for the detection of valvular regurgitation in horses. However, quantification of jet size and duration are important for distinguishing physiological backflow which occurs in normal horses (Blissitt and Bonagura 1995) from valvular regurgitation associated with cardiac murmurs.
Characterisation of beta‐adrenoceptors in equine digital veins: implications of the modes of vasodilatory action of isoxsuprine
Authors: ELLIOTT J. , SOYDAN J. 
Published: June 2010

SummaryIsolated equine digital veins (EDVs) were used to study β‐adrenoceptor mediated vasodilation and to examine isoxsuprine's vasodilatory mechanism of action. When the blood vessel wall tension was raised with potassium chloride solution (KCl; 59 mmol/l), the order of vasodilator potency of β‐agonists was: isoprenaline > fenoterol > noradrenaline > dobutamine > isoxsuprine. The β2‐selective adrenoceptor antagonist, ICI 118551 (1 nmol/1) caused a 6.74 and 6.65‐fold parallel shift to the right in the dose response curves to fenoterol and noradrenaline respectively. Propranolol (10 nmol/l) inhibited the vasodilatory action of isoprenaline in a competitive manner (19.6 ± 6.4‐fold parallel shift to the right) but was much less effective as an inhibitor of isoxsuprine's vasodilatory action. Isoprenaline and fenoterol were just as effective as vasodilators when blood vessel wall tension was raised with KCl, the thromboxanemimetic U44069 (9, 11‐dideoxy‐9α, 11α‐epoxymethano‐prostaglandin F2α; 30 nmol/l) or the α1‐adrenoceptor agonist, phenylephrine (0.3 μmol/l). In addition, fenoterol's relaxation of U44069‐induced tone was competitively inhibited by the β2‐selective adrenoceptor antagonist ICI 118551 (8.4 ± 0.9‐fold parallel shift to the right). By contrast, isoxsuprine was 81.9 times more potent as a vasorelaxant of phenylephrine‐induced tone when compared with KCl‐induced tone and proved completely ineffective as a vasodilator of U44069‐induced tone. When dose response curves to α‐adrenoceptor vasoconstrictor agonists were obtained in the presence of isoxsuprine (0.1 μmol/l), competitive antagonism occurred with methoxamine and noncompetitive antagonism with BHT‐920. These data suggest EDVs possess β2‐adrenoceptors mediating vasodilation. Isoxsuprine is an α1‐selective adrenoceptor antagonist but has very low potency and efficacy as a β‐adrenoceptor agonist in this functional bioassay. Indeed, much of the vasodilatory action of isoxsuprine may be due to a mechanism which does not involve β‐adrenoceptors.
Quinidine administration increases steady state serum digoxin concentration in horses
Authors: PARRAGA MARIA E. , KITTLESON M. D. , DRAKE CHRISTIANA M. 
Published: June 2010

SummaryThe aim of this study was to determine if quinidine administration increases steady state serum digoxin concentration in horses. Digoxin (0.01 mg/kg q. 12 hper os) was administered to 6 horses for 7 days. Steady state was confirmed by identifying statistically indistinguishable peak and trough serum digoxin concentrations on Days 4, 5, and 6. On Day 6, serum digoxin concentration was measured at baseline and 0.25, 0.5, 1, 2, 4, 6, 8 and 12 h after digoxin administration. On Day 7, quinidine (20 g at baseline and 10 g at 2, 4 and 6 h) was administeredper osand serum digoxin concentration was measured at the same time intervals. Creatinine and renal digoxin clearances were measured on Days 6 and 7. Results indicated that there was approximately a doubling of serum digoxin concentration (from mean ± s.d. 2.57 ± 0.96 ng/ml at baseline to 4.28 ± 1.31 at 15 min and 5.98 ± 1.21 ng/ml at 30 min) after starting the administration of quinidine.This elevation persisted for the 12 h after starting quinidine administration. Renal digoxin and endogenous creatinine clearances decreased but the decrease in digoxin clearance was greater. Serum quinidine concentration achieved the therapeutic range (2–6 μg/ml) in 5 of the 6 horses. In summary, similar to findings in other species, quinidine administration increases steady state serum digoxin concentration in horses and this occurs, at least in part, due to a decrease in renal digoxin clearance. Some of the decrease in renal clearance is due to decreased glomerular filtration which is dissimilar to findings in other species.