bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Reasons 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

Reasons 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

Reasons 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

Reasons 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

Reasons 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

Reason 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

Reasons 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

Reason 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

Reason 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.
Videoendoscopic evaluation of the upper respiratory tract in 93 sport horses during exercise testing on a high‐speed treadmill
Authors: FRANKLIN S. H. , NAYLOR J. R. J. , LANE J. G.
Published: June 2010

Reasons for performing study: Videoendoscopy of the upper respiratory tract (URT) during high‐speed treadmill exercise has proved to be invaluable in the assessment of URT dysfunction in racehorses. However, very little information exists regarding dynamic airway collapse in other sport horses used in nonracing equestrian disciplines.

Objectives: To evaluate the videoendoscopic findings at rest and during exercise in a mixed population of sport horses referred for investigation of poor athletic performance and/or abnormal respiratory noise.

Methods: Videoendoscopy of the upper airway was performed at rest and during high‐speed treadmill exercise in 93 horses.

Results: Dynamic airway obstructions were diagnosed in 77% of horses and were frequently complex in nature. The most common forms of dynamic collapse included soft palate dysfunction (54%), dynamic laryngeal collapse (38%), axial deviation of the aryepiglottic folds (24%) and pharyngeal wall collapse (18%). In the majority of horses, no obvious abnormalities were identified at rest. Enforced poll flexion was found to be a contributing factor in 24% of cases.

Conclusions: Dynamic obstructions of the URT were a common cause of poor performance and/or abnormal respiratory noise in sport horses referred for investigation of performance problems.

Potential relevance: This study highlights the importance of videoendoscopic evaluation of the URT during exercise in horses utilised for equestrian sports where exercise during competition is submaximal in nature.
Dynamic pharyngeal collapse in racehorses
Authors: BOYLE A. G. , . MARTIN B. B. , DAVIDSON E. J. , DURANDO M. M. , BIRKS E. K.
Published: June 2010

Reason for performing study: Dynamic pharyngeal collapse (PC) is a condition seen in racehorses that can be career‐ending.

Objectives: To characterise and grade PC and describe the effects of PC on athletic performance.

Methods: Medical records were reviewed for 828 horses, of which 49 (6%) records were identified as horses with a primary diagnosis of PC. Tapes of video‐endoscopy of the pharynx during exercise were reviewed. Each video recording was assigned a grade (0–4) reflecting the degree of PC and a classification for severity of upper airway obstruction. Earnings per race prior to diagnosis of PC were compared to earnings per race after diagnosis of PC for all horses, as well as performance index (PI). Available exercising arterial blood gases were reviewed for horses with PC.

Results: There were 35 (80%) Thoroughbreds (TB), and 9 (20%) Standardbreds (STD). 32 (73%) had a history of making an upper respiratory noise. 4 (9%)grade 1PC, 8 (18%)grade 2PC, 26 (59%)grade 3PC, and 6 (14%)grade 4PC. Seven (16%) horses were classified as mild PC, 18 (41%) as low‐moderate PC, 14 (32%) as high‐moderate PC, and 5 (11%) as severe PC. Of 30 horses 11 had abnormally decreased PaO2and 8 horses had abnormally elevated PaCO2. A significant decrease was found in earnings per race prediagnosis when compared to post diagnosis earnings per race in horses ≥4 years of age (P = 0.003). A significant decrease was also observed for earnings per race prediagnosis when compared to post diagnosis earnings per race in horses withgrade 3PC (P = 0.03) No significant differences were observed in PI before or after diagnosis of PC.

Conclusions: There was a trend for PC to be observed in more TB than STD, and more males than females compared to the general hospital population. Horses with PC significant had decreases in arterial oxygenation. Racing records after a diagnosis of PC in all horses ≥4 years of age suggesting that older horses have a guarded prognosis for continued success.

Potential relevance: This study provides a classification system for dynamic pharyngeal collapse and suggests that older racehorses (≥4 years of age) diagnosed with PC and all horses withgrade 3PC have a poor prognosis for return to previous level of performance.
Validation of a portable equine metabolic measurement system
Authors: ART T. , DUVIVIER D. H. , van ERCK E. , de MOFFARTS B. , VOTION D. , BEDORET D. , LEJEUNE J. P. , LEKEUX P. , SERTEYN D.
Published: June 2010

Reasons for performing study: In equine sports medicine, VO2 has been measured exclusively with stationary systems, in laboratories equipped with a treadmill. Measurement during exercise in field conditions has not previously been reported because of the lack of portable equipment designed for horses.

Objectives: A commercially available portable metabolic measurement system, based on breath‐to‐breath gas analysis and flow spirometry, was adapted to the horse's physiology and morphology (Cosmed K4b2 and Equimask)1 and its validity tested by (1) repeatability of the measures and (2) comparing metabolic data to those obtained by a reference method (RM).

Methods: To test the reproducibility of the measurements, 5 healthy saddle horses were subjected twice at 2 day intervals to a similar submaximal standardised incremental exercise test on a treadmill. The same horses performed twice at one week interval an incremental treadmill test to fatigue: the oxygen consumption and ventilation were measured once with the K4b2 system and once with the RM. The metabolic and ventilatory data obtained with both systems were compared.

Results: There was a good reproducibility of the metabolic measurements obtained by the K4b2 system at any workload. The VO2 obtained by both systems at any workload was not significantly different. However, the K4b2 expired fraction in CO2 (FETCO2) and carbon dioxide production (VCO2) were significantly lower at high and at maximal workloads. As a consequence, the values of the respiratory exchange ratio were too low and incompatible with normal physiological values.

Conclusions: The good reproducibility of the metabolic and ventilatory measurements and the fact that the VO2 measurements at any workload were similar to the data obtained with the reference method suggested that this system may be used for comparison of repeated VO2 measurements in practical field conditions.

Potential relevance: The K4b2 system could be used to improve knowledge of the energetic cost in different equine sports disciplines and offer the opportunity to undertake performance tests with genuine track conditions, on ridden or harnessed horses, rather than under laboratory conditions.
Oxygen consumption (V̇O2) during trotting on a 10% decline
Authors: HOYT D. F. , WICKLER S. J. , GARCIA S. F.
Published: June 2010

Reasons for performing study: Although there have been reports of oxygen consumption measurements of horses running on the level and incline, there are no measurements during decline locomotion. This may be due, in part, to the potential for muscle damage produced by eccentric contractions. In man, running on a 10% decline, V̇O2 decreased by 35% and stride frequency (SF) decreased by 3% when compared to level locomotion.

Hypothesis: The rate of O2 consumption and SF would be decreased in horses on a 10% decline when compared to the level.

Methods: Six horses (average 467 ± 68 kg) were acclimated to trotting on the level and decline prior to data collection. V̇O2 under moderate conditions was measured (using open flow respirometry) during trotting between 2.25 and 4.0 m/sec (at 0.25 m/sec increments) on a treadmill on the level and declined 10%. Stride frequencies were counted manually.

Results: V̇O2 decreased (P<0.009) on the decline by an average of 45% (range 42–47%), and SF was 2.7% slower. The speed at which the minimum Cost of Transport occurs on the decline was faster than on the level. SF was reduced on the decline. No evidence of muscle soreness was noted in response to the downhill running.

Conclusions and potential relevance: Downhill trotting, eccentric exercise, can be done safely in the horse and requires almost half the energetic costs as trotting on the level. It is not known whether this is the optimum downhill gradient or if the horse adjusts its preferred speed to accommodate downhill trotting.
Study of gelatin supplemented diet on amino acid homeostasis in the horse
Authors: COENEN M. , APPELT K. , NIEMEYER A. , VERVUERT I.
Published: June 2010

Reasons for performing study:Gelatin supplementation is a common measure in an attempt to assist cartilage repair, but little scientific evidence exists to support its efficacy.

Objectives:To investigate the effects of gelatin administration on post prandial homeostasis.

Methods:Twelve Standardbred horses (mean 404 kg bwt) were fed a hay‐concentrate diet supplemented by soy bean meal and oil (control [C], n=6) or with the addition of 60 g gelatin/day (G, n = 6). The horses were trained by an alternate order of interval and prolonged exercise every second day. The velocities of the treadmill corresponding to 2 and 10 mmol lactate/l blood were derived from lactate curves during a standardised exercise test at the start and middle of the 64 day training period. Blood samples for amino acid analysis were obtained weekly at rest (2 h post prandial). In the second part of the training period, a post prandial sampling was conducted on a day without exercise (prior feeding up to 8 h post prandial). Plasma free amino acids (AA) were determined by HPLC.

Results:The change from pre‐ to the training diet induced an increase in many AA during the total training period. At rest free glycine and proline in blood increased with gelatin supplementation during 7 days after the start of supplementation. The AA in plasma showed a post prandial curve with peak concentrations 2–3 h after feeding. Significant post prandial effects of gelatin intake were detectable for glycine, proline and arginine.

Conclusions:The AA from gelatin are absorbed quickly and become available for AA metabolism.

Potential relevance:It is evident that in the horse, gelatin influences the homeostasis of those amino acids required for cartilage synthesis. Further research is needed to elucidate the utilisation of those amino acids for the prevention or repair of cartilage damage.
Exercise response, metabolism at rest and digestibility in athletic horses fed high‐fat oats
Authors: LINDBERG J. E. , ESSÉN‐GUSTAVSSON B. , DAHLBORN K. , GOTTLIEB‐VEDI M. , JANSSON A.
Published: June 2010

Reason for performing study:High starch intakes increase the risk for metabolic disorders and therefore alternative feedstuffs are of interest. High‐fat oat varieties have a lower starch and higher energy content than regular oats and may therefore be useful in this context.

Hypothesis:Feeding high fat oats causes no adverse effects on the response to exercise and that the total amount of oats offered could be reduced compared to feeding with regular oats.

Methods:Twelve Standardbred trotters were fed regular oats (diet C), high‐fat oats (F), and a mixture (50:50) ofCandF(M), together with haylage (30:70), in a Latin square design trial. High‐fat oats replaced regular oats in a 0.9 to 1.0 ratio indiets FandM. On Day 18 in each 21 day experimental period, horses were subjected to a standardised near‐maximal treadmill exercise test with collection of blood samples and muscle biopsies before and after exercise. This was followed by a 3 day period of total collection of faeces and urine.

Results:There were no significant effects of dietary treatments on bodyweight, heart rate, plasma lactate and glucose, or on muscle glycogen and lactate concentrations following exercise. However, plasma insulin was reduced during exercise ondiets FandMcompared to dietC. The total tract digestibility of dry matter, fat, protein, NDF and organic matter were higher fordiet Fthan fordiet C.

Conclusion:High‐fat oats can replace regular oats in the diet of athletic horses without any adverse effects on metabolism and exercise response.

Potential relevance:Due to the high energy content and a high digestibility of dietary components in high‐fat oats the daily allowance of oats can be reduced and thus the intake of starch.
Glycaemic and insulinaemic response of Quarter Horses to concentrates high in fat and low in soluble carbohydrates
Authors: ZEYNER A. , HOFFMEISTER C. , EINSPANIER A. , GOTTSCHALK J. , LENGWENAT O. , ILLIES M.
Published: June 2010

Reasons for performing study:Quarter Horses are particularly susceptible to polysaccharide storage myopathy (PSSM). Nutritional therapy and possibly prophylaxis includes fat‐supplemented diets whilst starch supply should be kept to a minimum.

Objectives:To investigate the glycaemic and insulinaemic response of clinically normal Quarter Horses to concentrates high in fat and low in starch.

Methods:Twelve Quarter Horses were studied. The precondition for inclusion in the study population was that the horses had not shown clinical signs of myopathy. The Quarter Horses were fed according to a 4 times 4 Latin square design haylage plus isocaloric concentrates based on barley and oats as control (CO), sugar beet pulp, grass meal and soybean oil (SB), rice bran and grass meal (RB) and rice bran, grass meal, sugar beet pulp and soybean oil (CP), each over 2 weeks after 1 week of adaptation. At the end of each period, 1 kg of concentrate was fed and blood sampled 0, 30, 60, 90, 120, 180, 240, and 300 min post prandial (ppr.). Creatine kinase (CK; 0 min ppr. only), glucose and insulin were analysed. Glycaemic and insulinaemic index was calculated from each concentrates area under the curve (AUC) relative to CO.

Results:Rice bran containing concentrates were partially refused at the beginning of the trial periods. CK activity, and glucose and insulin patterns (ppr. mean, peak, AUC, index) were highest with CO (P<0.05). The correlation between glucose and insulin (P<0.001) ranged from r=0.570 (CO) to r = 0.364 (RB). Basal CK was highly correlated (P<0.001) to the mean ppr. plasma glucose.

Conclusion:Rice bran, sugar beet pulp, grass meal and soybean oil are suitable to include in concentrates that induce low glycaemic and insulinaemic response. Its acceptance seems to be a question of habituation. Although the mechanism is not completely understood, glucose patterns and basal CK activity are highly positively correlated. Both were affected by the type of concentrate used.

Potential relevance:Results support the suggestion that low‐starch and high‐fat feeding may be helpful not only in the nutrition of affected horses, but also to prevent future PSSM associated discomfort in particularly susceptible horses.
Effects on exercise response, fluid and acid‐base balance of protein intake from forage‐only diets in Standardbred horses
Authors: CONNYSSON M. , MUHONEN S. , LINDBERG J. E. , ESSÉN‐GUSTAVSSON B. , NYMAN G. , NOSTELL K. , JANSSON A.
Published: June 2010

Reason for performing study:High‐energy forage might be an alternative to concentrates for performance horses and such forage can be produced by an early cut. However, early cut forage is high in crude protein (CP), which may result in an excessive CP intake.

Objectives:To investigate how CP intake affects nitrogen (N), fluid and acid‐base balance, and exercise response in horses fed high‐energy forage diets. The hypothesis was that high CP intake causes acidosis, and alters fluid balance and response to intensive exercise.

Methods:Two forage‐only diets based on high‐energy grass forage were fed for 23 days in a crossover design to 6 Standardbred horses in racing condition. One forage diet provided a high (HP) CP (16.6%) intake and the other diet provided recommended intake (RP) of CP (12.5%) for racehorses. The horses had intensive exercise twice and slow exercise 1–3 times every week. At the beginning and end of each period, faeces and urine were collected for 48 and 72 h, respectively and analysed for dry matter, pH and N content. At Days 19 and 23 in each period 2 race‐like exercise tests were performed, a standardised treadmill test and a field test on a race track. Blood samples were taken before, during and after the tests and analysed for sodium (Na), potassium (K), chloride (CI), total plasma proteins (TPP), TCO2, urea, pH and lactate. The strong ion difference (SID) was calculated and heart rate and respiratory rate was also recorded.

Results:There was a decrease in urinary pH and an increase in N excretion, blood urea, water intake, urine volume and faecal water content on the HP diet. Total water intake was higher than the increase in urinary and faecal water loss indicating increased evaporative losses on the HP diet. During the exercise tests there were no significant differences between diets in TPP, plasma lactate, blood Na, K, CI, TCO2, pH, SID and respiratory or heart rates.

Conclusion:Feeding a forage‐only diet with a CP intake corresponding to 160% of the requirement caused an increase in N excretion within 36–48 h after the diet was introduced and alterations in fluid and acid base balance at rest.

Potential relevance:The increased urine and probably also evaporative fluid losses suggest that feeding a HP diet will cause an unnecessary challenge for horses during prolonged exercise.
The effect of milk basic protein supplementation on bone metabolism during training of young Thoroughbred racehorses
Authors: INOUE Y. , ASAI Y. , TOMITA M. , KURIBARA K. , KOBAYASHI M. , KANEKO M. , TOBA Y.
Published: June 2010

Reasons for performing study:In laboratory animals, man and cell culture experiments, milk basic protein was reported to suppress bone resorption and promote bone formation. However, no studies in horses have previously examined the effect of milk basic protein.

Objectives:To evaluate the effect of milk basic protein supplementation on bone metabolism in young Thoroughbred horses in training.

Methods:Twenty 2‐year‐old horses in training were used for 90 days in this study. The treatment group was fed a basal diet with 1 g of milk basic protein and the control group a basal diet only. Blood samples were collected on Days 0, 45 and 90 to determine serum calcium (Ca) and biochemical markers of bone metabolism. Radiographs were taken at the start and end of the study to determine radiographic bone aluminium equivalence (RBAE).

Results:Serum osteocalcin (OC) was significantly higher at Day 45 after the beginning of the study in the treatment group compared to that in the control group. The treatment group showed a greater increase in the total RBAE change at the end of this study compared to that in the control group. However, there were no significant differences in serum Ca and carboxy‐terminal telopeptide oftype Icollagen (ICTP) between groups.

Conclusions and potential relevance:These findings provide preliminary evidence that milk basic protein has an effect on bone formation in 2‐year‐old Thoroughbred horses in training. However, further studies in larger groups of horses are now required to substantiate our findings.
Effect of omeprazole on markers of performance in gastric ulcer‐free Standardbred horses
Authors: McKEEVER J. M. , McKEEVER K. H. , ALBEIRCI J. M. , GORDON M. E. , MANSO H. C.
Published: June 2010

Reasons for performing study:A large percentage of performance horses develop gastric ulcers and many of those horses are treated with omeprazole. Unfortunately, no data have been published on the effects of the drug on markers of performance in animals without ulcers.

Hypothesis:Omeprazole would alter markers of aerobic and anaerobic performance.

Methods:Ten unfit, healthy, ulcer free, Standardbred mares were administered either control (CON; oral apple sauce, 20 ml) or omeprazole (OP; oral paste, 4 mg/kg bwt s.i.d.) in a random crossover fashion with the investigators blind to the treatment. Treatments were administered for 7 days prior to performing an incremental exercise test (GXT) on a high‐speed treadmill. Endoscopic examinations were performed just prior to the trial to verify that the mares were ulcer‐free. During the GXT, the mares ran on a treadmill up a 6% grade to measure maximal oxygen consumption (V̇O2max), run time (RT), velocity at V̇O2max, maximal velocity (V̇max), packed cell volume (PCV), plasma lactate concentration (LA) and plasma protein concentration (TP). Measurements were recorded at rest, at the end of each 1 min step of the GXT and at 2 and 5 min post GXT. Data were analysed using ANOVA for repeated measures andttests for paired comparisons.

Results:There was no effect (P>0.05) of omeprazole on V̇O2max; velocity at V̇O2max; RT; V̇max; 2 min recovery plasma LA. Nor were there any changes (P>0.05) in the relationship between treadmill speed and VO2, PCV, TP, or plasma LA.

Conclusions:Omeprazole does not appear to improve physiological markers of performance in healthy, ulcer free horses.

Potential relevance:These data may benefit various authorities responsible for deciding administration and timing policies of omeprazole as well as clinicians and horse owners.
Peritoneal concentrations of transforming growth factor beta in horses with colic
Authors: ARGÜELLES D. , CASTELJINS G. , CARMONA J. U. , ARMENGOU L. , CLIMENT F. , PRADES M.
Published: June 2010

Reasons for performing the study: In man, peritoneal transforming growth factor beta (TGF‐β) is associated with peritoneal diseases and subsequent adhesion formation. No studies on plasma and peritoneal TGF‐β concentrations in horses with colic are available.

Objectives: 1) To determine both plasma and peritoneal TGF‐β1 and TGF‐β3 concentrations in horses with different types of colic (not previously subjected to abdominal surgery); 2) to compare these concentrations according to the type of peritoneal fluid (transudate, modified transudate and exudate); and 3) to compare and correlate plasma and peritoneal concentrations of TGF‐β1 and TGF‐β3 and the types of peritoneal fluid according to the colic group and outcome.

Methods: Peritoneal fluid and plasma samples from 78 horses with colic and 8 healthy horses were obtained. Patients were classified according to diagnosis (obstructions, enteritis, ischaemic disorders and peritonitis), peritoneal fluid analysis (transudate, modified transudate and exudate), and outcome (survivors and nonsurvivors). Plasma and peritoneal TGF‐β1 and TGF‐β3 concentrations were determined by ELISA. Data were analysed by parametric and nonparametric tests. P≤0.05 was considered as statistically significant.

Results: Concentrations of peritoneal fluid TGF‐β1 were significantly (P = 0.01) higher in horses with peritonitis in comparison with all other colic groups and controls. Horses with ischaemic lesions had significantly (P = 0.01) higher concentrations of peritoneal TGF‐β1 in comparison with controls and the group of horses with obstructions. Peritoneal TGF‐β1 concentration also was significantly (P = 0.01) higher in exudates in comparison with transudates. Peritoneal TGF‐β1 and TGF‐β3 concentrations and plasma TGF‐β1 concentration were significantly increased in nonsurvivors compared to survivors (P = 0.001, P = 0.004 and P = 0.05, respectively).

Conclusions: Peritoneal TGF‐β1 concentration was higher in horses with severe gastrointestinal diseases (ischaemic intestinal lesions and peritonitis), in horses with an altered peritoneal fluid (exudate), and in nonsurvivors.

Potential relevance: Peritoneal TGF‐β concentration increases in horses with severe gastrointestinal disease as an anti‐inflammatory response.
Tiludronate infusion in the treatment of bone spavin: A double blind placebo‐controlled trial
Authors: GOUGH M. R. , THIBAUD D. , SMITH R. K. W.
Published: June 2010

Reasons for performing study: Tiludronate regulates bone remodelling through a decrease of the resorptive process and should therefore ameliorate the remodelling processes active in osteoarthritis of the distal tarsal joints (‘bone spavin’) and alleviate pain associated with abnormal bone lysis.

Objective: To confirm the efficacy of tiludronate, administered as a single infusion at a dose of 1 mg/kg bwt, in the treatment of bone spavin in the horse.

Methods: A double blind placebo controlled trial on 108 clinical cases of bone spavin was undertaken. The lameness score of the lamest limb was assessed following distal tarsal analgesia of the contralateral limb and followed‐up using the same procedure throughout the study. Bone spavin in the lamest limb was confirmed by distal tarsal analgesia and radiography. Horses were treated at Day 0 and reassessed 60 days later after controlled exercise. A second nonblinded treatment was given to unresponsive horses and all horses were re‐examined at Day 120. Exercise levels were recorded at each examination.

Results: Eighty‐seven horses completed the trial as per the protocol. The tiludronate horses were significantly less lame than the placebo horses (P = 0.0318). Horses treated at Day 60 with tiludronate showed further improvement in lameness at Day 120 (P = 0.0096 and P = 0.0034 for horses treated with tiludronate and placebo at Day 0, respectively). The only significant difference in radiographic findings between tiludronate and placebo was for presence of periarticular osteophytes (P = 0.006).

Conclusions: Tiludronate treatment is proven to be effective in bone spavin in horses in association with a controlled exercise programme.

Clinical relevance: Tiludronate in combination with controlled exercise offers an alternate medical treatment for bone spavin.
Antagonism of rat orexin receptors by almorexant attenuates central chemoreception in wakefulness in the active period of the diurnal cycle
Authors: Li Aihua , Nattie Eugene
Published: June 2010

Central chemoreception, the highly sensitive ventilatory response to small changes in CO2/pH, involves many sites. Hypothalamic orexin neurons are CO2 sensitive in vitro, prepro‐orexin knockout mice have a reduced CO2 response prominently in wakefulness, and focal antagonism of the orexin receptor 1 (OX1R) in two central chemoreceptor sites, the retrotrapezoid nucleus (RTN) or the medullary raphé, results in a reduction of the CO2 response predominately in wakefulness (−30% and −16%, respectively). Here we hypothesize that acute and selective inhibition of both orexin receptors (OX1R and OX2R) at all central locations by an orally administered dual orexin receptor antagonist, almorexant, will substantially attenuate the CO2 response in a vigilance‐state‐ and diurnal‐cycle‐dependent manner. We found that almorexant attenuated the CO2 response by 26% only in wakefulness during the dark period of the diurnal cycle to a level observed during NREM sleep in the light period in controls suggesting that the sleep–wake difference in the CO2 response can be in large part attributed to orexin. Almorexant also decreased wakefulness and increased NREM and REM sleep during the dark period, as previously reported, and unexpectedly decreased the number of sighs and post‐sigh apnoeas during wakefulness in both the light and the dark period and during both wakefulness and NREM sleep in the dark period. The results support our hypothesis that the orexin system participates importantly in central chemoreception in a vigilance‐state‐ and diurnal‐cycle‐dependent manner and indicate a role for orexin in the important process of sighing.
The illusion of changed position and movement from vibrating one arm is altered by vision or movement of the other arm
Authors: Izumizaki Masahiko , Tsuge Mikio , Akai Lena , Proske Uwe , Homma Ikuo
Published: June 2010

Experiments were carried out on blindfolded human subjects to study the contribution of proprioceptive inputs from both arms in a forearm position matching task. Blindfolded matching accuracy was compared with accuracy when the subject could see their indicator (matching) arm, when they used a dummy arm for matching, and when they looked at a mirror image of the matching arm. The position of the mirror had been arranged so that the image of the indicator arm coincided with the position of the reference arm. None of these conditions significantly altered the matching errors. When reference elbow flexors were vibrated at 70–80 Hz, the illusion of extension of the vibrated arm reported by blindfolded subjects was significantly reduced by vision of the mirror image of the indicator arm or when using the dummy arm. It was concluded that visual information about the position of the indicator arm, or the apparent position of the reference arm, could reduce the size of the kinaesthetic illusion from vibration, but not abolish it. In a second experiment, subjects indicated, by tracking with their vibrated arm, the illusion of forearm extension evoked by elbow flexor vibration. It was found that the perceived speed of extension could be reduced by moving the indicator into extension and increased by moving it into flexion. These experiments demonstrate the importance for the matching process of the input provided by the indicator arm. Such a conclusion may help to explain some apparent discrepancies between observations made on position sense using one‐arm and two‐arm tasks. More broadly, this paper provides support for the idea that aspects of proprioceptive inputs from both arms are processed conjointly, as part of a strategy for use of the two hands as a single instrument in certain skilled tasks.