bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating peak strains associated with fast exercise in Thoroughbred racehorses
Authors: DAVIES H. M. S. 
Published: June 2010

SummaryReasons for performing study:The third metacarpal bones (MC3) of racing Thoroughbreds are a common site for bone damage. The midshaft dorsal cortex (DC) of MC3 thickens in response to fast exercise. It is not clear if it changes to a shape and size that limits the peak bone strains to a range associated with normal loading in other species.Objectives:To relate the proportionate size of the DC cortex in racehorses exercising at racing speed to surface strains, and test whether the DC reached a plateau that was sustained through subsequent exposures to racing speed exercise.Methods:Standardised lateral MC3 radiographs were taken weekly for 2–5 years in 40 racehorses in race training (16–19 m/sec). DC, medulla (M), and palmar cortex (PC) thickness were measured, at 2.5 cm distal to the nutrient foramen. An index (RI) of the relative thickness of the DC was calculated for each radiograph (RI = [DC+PC]/ M multiplied by [DC/PC]) and used to calculate strains at 12 m/sec from an equation published previously.Results:Mean time to plateau in DC thickness was 501 days, mean increase in DC was 3.9 mm on the left and 3.7 mm on the right. Rate of change was 8.8 μm/day on the left, and 8.4 μm/day on the right during this time. In most horses the medulla width did not change between the first and last measurements so these bone growth rates reflect periosteal bone growth on the DC surface. No further significant change in DC or RI was found, once they had reached a plateau. Mean DC thickness at the plateau was 14.7 mm on the left and 14.9 mm on the right. Mean RI at the plateau was 3.7. This equated to peak microstrains at 12 m/sec of ‐2492 and suggests that strains much greater than 3000 microstrains occur at racing speed in most horses.Conclusions:Experienced racehorses are likely to be exposed to peak strains beyond the normal limit for adult mammalian bone to resist without damage and strains associated with very fast exercise may not be sufficient stimulus to induce further bone modelling in these horses.Potential relevance:Strains occur in the bones of experienced racehorses at a higher level than normal for other mammalian bones. Hence there may be other mechanisms operating in this particular bone in racehorses that protects the bone from failure when exposed to the high strains associated with fast exercise speeds. Investigation of such mechanisms may provide an insight on how to reduce the likelihood of damage to this bone during very fast exercise.
Gait pattern of the ataxic horse compared to sedated and nonsedated horses
Authors: STROBACH A. , KOTSCHWAR A. , MAYHEW I. G. , PEHAM C. , LICKA T. 
Published: June 2010

SummaryReasons for performing study:Equine ataxia is routinely evaluated subjectively by clinicians; however, objective measurements of the movement and coordination of ataxic horses have not been reported.Objectives:To document the movement pattern of ataxic horses and compare the results to the movement of neurologically sound horses with, and without, sedation.Methods:Seventeen ataxic horses were evaluated walking and trotting on a treadmill using a 3D high speed video system. From the horizontal movement of hoof markers the autocorrelation function (ACF) of the left forelimb and the cross correlation function (CCF) between the left forelimb and other 3 limbs (CCF foreleft/hindright [flhr], foreleft/hindleft [flhl], foreleft/foreright [flfr]) was calculated. This resulted in a value of motion cycle consistency. The results were compared to data of 17 neurologically normal horses with, and without, sedation with detomidine. For statistical analysis thettest for independent samples was used.Results:Comparing normal (NO) and ataxic (AT) horses at the walk, highly significant differences for the ACF and for all the CCFs were documented. At the trot, ACF and CCFs flhr and flfr were significantly different in the NO and AT groups. Comparing sedated and ataxic horses, only the CCF flfr at walk and at trot were significantly different.Conclusion and potential relevance:Ataxia is best documented and examined at the walk. At trot pendulum effect may make coordination easier for horses. The results of this study serve as basic data for evaluating questionably ataxic horses.
The effect of gallop training on hoof angle in Thoroughbred racehorses
Authors: PEEL J. A. , PEEL M. B. , DAVIES H. M. S. 
Published: June 2010

SummaryReasons for performing study:The economic impact of soundness problems in racehorses is very high and low hoof angle at the toe has been associated with a lack of soundness. However, it is not clear what environmental and management factors might contribute to a low hoof angle.Objectives:To investigate the hypothesis that the hooves of racehorses become flatter when in gallop training, as well as to determine factors contributing to this trend.Methods:Weekly hoof measurements were taken with a hoof gauge from 45 Thoroughbred racehorses; 4 Thoroughbred show horses kept in consistent conditions and shod by the same farrier as some of the racehorses; and 6 unshod free‐ranging horses. A further 15 horses were measured twice in one day to determine the repeatability of the method.Results:Repeatability coefficients were 0.31° for the left hoof and 0.37° for the right. Racehorses in training showed a significant decrease in hoof angle over time while free ranging horses and show horses did not. Free‐ranging horses had a significantly lower angle in winter (wet) compared with summer (dry) in both left (P=0.040) and right (P=0.017). Show horses had no significant change in hoof angle. Racehorses that had a period of rest during the experiment (n=11) showed a decrease in hoof angle during training and an increase over their rest period for both hooves (P=0.005 for the left hoof, P = 0.0009 for the right).Conclusions:Training for fast exercise in Thoroughbred racehorses is associated with a reduction in hoof angle and wet pasture conditions may also be associated with a reduced hoof angle in free‐ranging horses.Potential relevance:Gallop exercise has a potentially large effect on hoof angle and therefore, a change in angle should be expected to occur in racehorses starting fast exercise work. Hence management of horses with abnormally low hoof angles may require an adaptation to their training regime in order to minimise this effect.
Effect of uphill exercise on equine superficial digital flexor tendon forces at trot and canter
Authors: TAKAHASHI T. , KASASHIMA Y. , ETO D. , MUKAI K. , HIRAGA A. 
Published: June 2010

SummaryReasons for performing study:One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe‐wedge shoe. Uphill courses are used for training of racehorses, and the angle of hoof‐sole to the horizon during uphill running is similar to that of the toe‐wedge shoe.Objectives:To determine the effects of uphill exercise on the force on the SDFT during trotting and cantering.Methods:Arthroscopically implantable force probes (AIFP) were implanted into the SDFT of the left or right forelimb of 7 Thoroughbred horses and AIFP output recorded during trotting and cantering on a treadmill inclined at slopes of 0,3 or 8%, and then 0% again. Superficial digital flexor tendon force was calculated as a relative value, with the amplitude of AIFP output voltage at initial 0% slope equal to 100.Results:Out of 14 sets of experiments, AIFP data were analysed successfully in 9 at the trot, in 3 at the canter in the trailing forelimb on a slope of 3 and 8%, and in 2 at the canter in the leading forelimb on a slope of 3%. Increasing the incline from 0–8% tended to decrease peak force in the SDFT at the trot, and in the trailing forelimb at the canter. However, force in the SDFT was unchanged in the leading forelimb at the canter on the 3% incline.Conclusions:The force in the SDFT trotting or cantering uphill is unchanged or lower than that loaded at the same speed on a flat surface. Because at similar speeds the workload for uphill exercise is greater than on the flat, uphill running increases exercise intensity without increasing force in the SDFT.Potential relevance:Uphill exercise may reduce the risk of SDFT injury as both running speed and SDFT force are decreased on an incline as compared to the flat, even when exercise intensity is the same. Further study is needed to confirm these findings at canter in a larger population of horses.
Determination of mechanical loading components of the equine metacarpus from measurements of strain during walking
Authors: MERRITT J. S. , BURVILL C. R. , PANDY M. G. , DAVIES H. M. S. 
Published: June 2010

SummaryReasons for performing study:The mechanical environment of the distal limb is thought to be involved in the pathogenesis of many injuries, but has not yet been thoroughly described.Objectives:To determine the forces and moments experienced by the metacarpusin vivoduring walking and also to assess the effect of some simplifying assumptions used in analysis.Methods:Strains from 8 gauges adhered to the left metacarpus of one horse were recordedin vivoduring walking. Two different models ‐ one based upon the mechanical theory of beams and shafts and, the other, based upon a finite element analysis (FEA) ‐ were used to determine the external loads applied at the ends of the bone.Results:Five orthogonal force and moment components were resolved by the analysis. In addition, 2 orthogonal bending moments were calculated near mid‐shaft. Axial force was found to be the major loading component and displayed a bi‐modal pattern during the stance phase of the stride. The shaft model of the bone showed good agreement with the FEA model, despite making many simplifying assumptions.Conclusions:A 3‐dimensional loading scenario was observed in the metacarpus, with axial force being the major component.Potential relevance:These results provide an opportunity to validate mathematical (computer) models of the limb. The data may also assist in the formulation of hypotheses regarding the pathogenesis of injuries to the distal limb.
Effects of draw reins on limb kinematics
Authors: BYSTRÖM A. , ROEPSTORFF L. , JOHNSTON C. 
Published: June 2010

SummaryReasons for performing study:No data exist on the GRF‐kinematics relation due to changes caused by equestrian interventions.Hypothesis:Through the judicious use of draw reins the rider can influence the kinematics of the horse to meet stated goals of dressage training. Relating the results to previously published kinetic data of the same experiment implies a possible relationship between kinetics and kinematics.Methods:The kinematics of 8 sound Swedish Warmblood horses were measured whilst the horses were being ridden with and without draw reins. Three conditions were evaluated: 1) draw reins only (DR), 2) combination of draw reins and normal reins (NR+DR) and 3) normal reins only (NR).Results:Head and neck angles were significantly decreased by the draw rein but 4–5 times more so for DR when with NR+DR. The forelimb position at hoof lift‐off was significantly more caudal with DR. In the hind limb the hip joint extended more quickly and the hock joint flexed more with NR+DR than with NR. Compared to DR the hip joint angular pattern was not significantly different, but the pelvis was more horizontal.Conclusion:Riding with a draw rein can have significant influence on the kinematics of the horse. Some of the observed changes can be coupled to changes in kinetics. The hock joint angle seems to be a fairly reliable indicator of load on the hind limb and the angle of femur appears important for hind limb propulsion, when considered in conjunction with the orientation of the pelvis.Potential relevance:These findings are important for riders and trainers, as kinematic changes are what trainers observe. It is thereby important to ascertain which kinematic changes are consistently coupled to changes in kinetics in order for trainers to be able to judge correctly the success of intended goals. Further studies are warranted to validate and confirm suggested relationships between kinetics and kinematics.
Movement between the equine ilium and sacrum:in vivoandin vitrostudies
Authors: GOFF L. M. , JASIEWICZ J. , JEFFCOTT L. B. , CONDIE P. , McGOWAN T. W. , McGOWAN C. M. 
Published: June 2010

SummaryReasons for performing study:Sacroiliac disease (SID) is an important cause of loss of performance in horses, yet little is known about the biomechanics of movement of the sacroiliac joint (SIJ).Objectives:(a) To document the presence of equine SIJ motion by measuring the change in cross‐sectional area (CSA) of the dorsal portion of the dorsal sacroiliac ligament (DSIL) during application of manual forces to the pelvis, and to ascertain if this varied between horses with SID and normal horses; (b) To determine the amount and direction of motion available at the equine SIJ using 3‐D orientation sensors, and how motion is limited by the DSIL and sacrotuberous ligament.Methods: Study 1:CSA obtained ultrasonographically was compared before and during manual force application to the ilium, on a group of 10 horses, 5 with SID and 5 clinically normal.Study 2:direction and degrees of motion between sacrum and ilium were measured in 8 cadaveric SIJs. 3D orientation sensors were mounted to the fixated sacrum and the moveable ilium, and relative motion recorded between the 2 bones when manual forces were applied to the ilium.Results: Study 1showed a significant decrease in the CSA of the equine DSIL during application of manual forces to bothtuber coxae(TC) (P<0.001) andtuber sacrale(TS) (P<0.001) when compared to at rest.Study 2described range of motion to be greatest in the transverse or coronal plane, when lateral and oblique forces were applied to the pelvis, and recorded significant increases (P<0.05) in range of motion in the sagittal plane following resection of both the DSIL and sacrotuberous ligament.Conclusion and potential relevance:The change in DSIL CSA with application of manual force may be due to a lengthening of the ligament, reflecting equine SIJ motionin vivo.The motion recorded between ilium and sacrumin vitrosuggests that greatest sacroiliac motion may occur in the transverse plane. Increases in range of motion following resection of ligaments give some indication of the role of each ligament.
Nitric oxide synthase inhibition in Thoroughbred horses augments O2 extraction at rest and submaximal exercise, but not during short‐term maximal exercise
Authors: MANOHAR M. , GOETZ T. E. , HASSAN A. S. 
Published: June 2010

SummaryReason for performing study: Work is required to establish the role of endogenous nitric oxide (NO) in metabolism of resting and exercising horses.Objectives: To examine the effects of NO synthase inhibition on O2 extraction and anaerobic metabolism at rest, and during submaximal and maximal exertion.Methods: Placebo and NO synthase inhibition (with Nω‐nitro‐L‐arginine methyl ester [l‐NAME] administered at 20 mg/kg bwt i.v.) studies were performed in random order, 7 days apart on 7 healthy, exercise‐trained Thoroughbred horses at rest and during incremental exercise leading to 120 sec of maximal exertion at 14 m/sec on a 3.5% uphill grade.Results: At rest, NO synthase inhibition significantly augmented the arterial to mixed‐venous blood O2 content gradient and O2 extraction as mixed‐venous blood O2 tension and saturation decreased significantly. While NO synthase inhibition did not affect arterial blood‐gas tensions in exercising horses, the exercise‐induced increment in haemoglobin concentration and arterial O2 content was attenuated. In the l‐NAME study, during submaximal exercise, mixed‐venous blood O2 tension and haemoglobin‐O2 saturation decreased to a greater extent causing O2 extraction to increase significantly. During maximal exertion, arterial hypoxaemia, desaturation of haemoglobin and hypercapnia of a similar magnitude developed in both treatments. Also, the changes in mixed‐venous blood O2 tension and haemoglobin‐O2 saturation, arterial to mixed‐venous blood O2 content gradient, O2 extraction and markers of anaerobic metabolism (lactate and ammonia production, and metabolic acidosis) were not different from those in the placebo study.Conclusion: Endogenous NO production augments O2 extraction at rest and during submaximal exertion, but not the during short‐term maximal exercise. Also, NO synthase inhibition does not affect anaerobic metabolism at rest or during exertion.Potential relevance: It is unlikely that endogenous NO release modifies aerobic or anaerobic metabolism in horses performing short‐term maximal exertion.
Pre‐exercise hypervolaemia is not detrimental to arterial oxygenation of horses performing a prolonged exercise protocol simulating the second day of a 3‐day equestrian event
Authors: TENNENT‐BROWN B. S. , GOETZ T. E. , MANOHAR M. , HASSAN A. S. , FREEMAN D. E. , BUNDY J. S. , EVANS M. R. 
Published: June 2010

SummaryReasons for performing study:Hyperhydration, prior to prolonged moderate‐intensity exercise simulating the 2nd day of a 3‐day equestrian event (E3DEC), may induce arterial hypoxaemia detrimental to performance.Objectives:Because moderate‐intensity exercise does not induce arterial hypoxaemia in healthy horses, the effects of pre‐exercise hypervolaemia on arterial oxygenation were examined during a prolonged exercise protocol.Methods:Blood‐gas studies were carried out on 7 healthy, exercise‐trained Thoroughbred horses in control and hyperhydration experiments. The study conformed to a randomised crossover design. The sequence of treatments was randomised for each horse and 7 days were allowed between studies. Hyperhydration was induced by administering 0.425 g/kg bwt NaCl via nasogastric tube followed by free access to water. The exercise protocol was carried out on a treadmill set at a 3% uphill grade and consisted of walking at 2 m/sec for 2 min, trotting for 10 min at 3.7 m/sec, galloping for 2 min at 14 m/sec (which elicited maximal heart rate), trotting for 20 min at 3.7 m/sec, walking for 10 min at 1.8 m/sec, cantering for 8 min at 9.2 m/sec, trotting for 1 min at 5 m/sec and walking for 5 min at 2 m/sec.Results:NaCl administration induced a significant mean ± s.e. 15.5 ± 1.1% increase in plasma volume as indicated by a significant reduction in plasma protein concentration. In either treatment, whereas arterial hypoxaemia was not observed during periods of submaximal exercise, short‐term maximal exertion caused significant arterial hypoxaemia, desaturation of haemoglobin, hypercapnoea, and acidosis in both treatments. However, the magnitude of exercise‐induced arterial hypoxaemia, desaturation of haemoglobin, hypercapnoea, and acidosis in both treatments remained similar, and statistically significant differences between treatments could not be demonstrated.Conclusions:It was concluded that significant pre‐exercise expansion of plasma volume by this method does not adversely affect the arterial oxygenation of horses performing a prolonged exercise protocol simulating the 2nd day of an E3DEC.
Effect of corticosteroid and bronchodilator therapy on bronchoalveolar lavage cytology following intrapulmonary blood inoculation
Authors: WALKER H. J. , EVANS D. L. , SLOCOMBE R. F. , HODGSON J. L. , HODGSON D. R. 
Published: June 2010

SummaryReason for performing study:Intrapulmonary blood causes an inflammatory response. Modifying this inflammatory response may be useful in the treatment of exercise induced pulmonary haemorrhage (EIPH).Objectives:To evaluate the efficacy of 3 treatments, an oral bronchodilator, inhaled steroid and oral steroid in modifying the cellular response to intrapulmonary blood inoculation.Materials and methods:Experimental design was a randomised block divided into 4 experimental segments of 2 weeks. Eight normal horses were randomly assigned to pairs and treatments. Autologous blood was inoculated into the lungs on 4 occasions over an 8 week period. For each treatment, a bronchoalveolar lavage (BAL) sample was collected on Day 0 and then 2 randomly selected segmental bronchi (one in each lung) were inoculated with blood (50 ml). BAL fluid was collected from one inoculated bronchus on Day 3 and from the other on Day 10. From BAL samples, total RBC and total and differential WBC were determined. Results for percentages and absolute cell counts were expressed as mean ± s.e. and analysed using one, 2 and 3 way analysis of variance.Results:All treatments significantly reduced the number of erythrophages at Day 3 (P=0.02) Treatment with oral prednisolone resulted in a significantly higher percentage of macrophages (P=0.03) and also reduced the relative and absolute number of haemosiderophages in BAL compared to the other 2 treatments at Day 10 (P = 0.07).Conclusion:We concluded that treatments altered the dynamics of cell populations in BAL following blood inoculation. Whether this alters the evolution of lung lesions following episodes of EIPH and indeed whether there are benefits for equine lungs following episodes of EIPH, remain to be determined.Potential relevance:Future studies into treatments for EIPH may benefit from incorporating a variety of dose rates for oral prednisolone and a longer period of evaluation. Such studies may also benefit from the use of cell activation markers. The concomitant use of pulmonary function testing and cytology in the field may assist in ascertaining whether treatments influence the performance and welfare of athletic horses subsequent to episodes of EIPH.
Cold air‐induced late‐phase bronchoconstriction in horses
Authors: DAVIS M. S. , ROYER C. M. , McKENZIE E. C. , WILLIAMSON K. K. , PAYTON M. , MARLIN D. 
Published: June 2010

SummaryReason for performing study:Inspired air is warmed to body temperature and fully humidified by the upper airway mucosa under normal resting conditions. This conditioning process may not be completed by the upper airways during conditions of increased minute ventilation or when the inspired air is unusually cold, resulting in cooling and desiccation of lower respiratory surfaces. Excess heat and water loss from intrapulmonary airways is believed to be the provocative stimulus for exercise‐induced bronchoconstriction (occurring immediately after exercise) and associated late phase airway obstruction (occurring a few hours after exercise).Hypothesis:Exercise while breathing cold air results in airway obstruction in horses.Methods:Eight healthy horses performed a 15 min submaximal exercise challenge in a random crossover design. Independent variable was inspired air temperature during the challenge (25 or ‐5°C). The dependent variables were total respiratory impedance, resistance, and reactance at 5, 24 and 48 h post exercise challenge, expressed as a percentage of the prechallenge baseline.Results:No significant effect of inspired air temperature was found on any respiratory mechanical parameter 5 h after exercise challenge. However, cold inspired air was associated with higher respiratory impedance and resistance 48 h after the exercise challenges.Conclusions:These findings support the hypothesis that submaximal exercise while breathing subfreezing air can adversely affect respiratory mechanical properties in normal horses. However, the timecourse for development of abnormal respiratory mechanical properties is longer than that reported in other mammals.Clinical relevance:Exercise in cold weather may be a common cause of lower airway disease in horses.