bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical properties of metacarpal bones of foals fed different energy and phosphorous levels
Authors: LEACH D. H. , CYMBALUK NADIA F. , HENDRIX ARLENE , WILLIAMS K.
Published: June 2010

The mechanical and geometric properties of metacarpal bones of 41 Quarter Horse yearlings fed diets with different energy and phosphorus levels were tested and compared. A 2 times 3 factorial experiment was used to compare 2 energy sources and 3 levels of dietary phosphorus. The 2 energy sources were based either on alfalfa (2.65 Mcal digestible energy [DE]/kg dry matter [DM] feed) or on grain (3.09 Mcal DE/kg DM). In each diet type, the 3 phosphorus concentrations included: an unsupplemented, low phosphorus (LP) diet; a normal phosphorus (NP) diet supplemented to meet NRC (1978) requirements for weanling foals; and a high phosphorus (HP) diet supplemented to supply 150% of 1978 NRC phosphorus requirements. At the completion of the feeding trial, the yearling horses were destroyed and the metacarpal bones recovered. The left metacarpus was serially sectioned at 0.5 cm thicknesses with a band saw and a section was sampled for histology and measurement of geometric properties including the rectangular moments of inertia (Ix, Iy), the products of inertia and principal moments of inertia (Ixx, Iyy). The moments of inertia were then recalculated to the change in orientation of the x‐y axes and symbolised Ix1 and Iy1. Energy intakes were similar despite differences in energy content of the forage and grain diets. However, forage‐fed yearlings had lower (p<0.0589) breaking strengths (23.4 kilograms per square inch [ksi] than grain‐fed horses (25.4 ksi). The geometric properties between LP and NP groups did not differ. However, the geometric properties (Ix1, Ixx, Iyy) differed (p<0.05) between the HP groups and the LP and NP groups. Within the NP group, (Iyy) differed (p<0.038) between males and females. The right metacarpus, with both small metacarpal bones removed but with the periosteum intact, was loaded in a 4‐point bending until failure. The metacarpal bones were placed in a specially‐made Instron tester made so that the mid‐diaphyses were loaded. All bones failed in a single plane at right angles to the main axis of the bone. Seventeen of the 41 bones (41.5%) fractured through the nutrient foramen. The mechanical properties of males and females did not differ except in the NP group wherein stiffness of the metacarpal bone of females was lower (p<0.05). In the NP group, males were 14% heavier (p<0.0384) than females. Although most mechanical properties did not differ between the LP and NP groups, the HP group had a higher load at yield point (6397 N) than the LP group (5789 N). Phosphorus intakes, therefore, affect both mechanical strength and geometric properties of growing horses.
The influences of different treadmill constructions on ground reaction forces as determined by the use of a force‐measuring horseshoe
Authors: ROEPSTORFF L. , JOHNSTON C. , DREVEMO S.
Published: June 2010

In the present study, 3 horses trotted at a series of different speeds on a SätoTM treadmill and a coir mat treadmill to determine the differences in ground reaction forces due to the surface of the treadmills. The horses were equipped with a force‐measuring horseshoe to quantify the ground reaction forces which were analysed with spectral analysis. Significant differences between the 2 treadmills were seen in frequency content of the power spectrum for the vertical force at the frequency interval 30–80 Hz and for the fore‐aft force at 30–40 Hz and 70–120 Hz.
An index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions
Authors: SCHROTER R. C. , MARLIN D. J.
Published: June 2010

There is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3‐day‐events in environments where there is likely to be a high level of radiation added to high ambient temperatures and relative humidity; the presently used FEI ‘Comfort Index’ is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as:

WBGT = 0.7Twb + 0.3Tg

where Twb is the wet bulb temperature of the ambient air, measured in the shade and Tg is the black globe temperature. Climatic conditions should be monitored continuously at a site representative of the detailed topography and nature of the terrain of the competition course.

The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5°C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
Estimation of metabolic energy cost and heat production during a 3‐day‐event
Authors: JONES J. H. , CARLSON G. P.
Published: June 2010

The metabolic power required for sustained exercise in the horse is proportional to running speed. Moderately fast speeds require substantial energy expenditure and result in the generation of a massive metabolic heat load. Quantitative estimates of energy expenditure and heat production of horses at various running speeds were developed using empirically derived data from treadmill studies. Total metabolic power represents the sum of aerobic power indicated by the rate of oxygen consumption and net anaerobic power indicated by the rate of plasma lactate accumulation. These data were applied to typical running speeds and distances for each of the 4 phases of the endurance day of an Olympic level (CCI****) 3‐day‐event to provide an estimate of the energy expenditure and heat production during each phase. In a given horse, the rates of energy expenditure and heat production are determined by running speed, while total energy expenditure and heat production are determined by a combination of running speed and duration of exercise at that intensity. The highest calculated rate of energy expenditure and heat production occurred during Phase B, the steeplechase, followed closely by Phase D, the cross‐country course. Interestingly, the highest total energy expenditure and heat production occurred on Phase C, Roads and Tracks, which is usually considered a period for cool down and recovery between the relatively high speed steeplechase and the demanding cross‐country course. Nevertheless, because the rate of energy expenditure is low during this phase, the horses would be expected to lose heat and lower body temperature during this interval. In hot and humid climates, dissipation of the exercise‐induced heat load may be compromised, leading to a narrower range of safety between the rate of heat production and the ability of the horse to dissipate this heat to the environment The results of this study could be used, should environmental conditions dictate, to provide quantitative guidelines as to how specific alterations of speed or distance of the various phases of the event would affect heat production.
Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI**** 3‐day‐event
Authors: MARLIN D. J. , HARRIS PATRICIA A. , SCHROTER R. C. , HARRIS R. C. , ROBERTS C. A. , SCOTT C. M. , ORME C. E. , DUNNETT M. , DYSON SUE J. , BARRELET F. , WILLIAMS B. , MARR CELIA M. , CASAS I.
Published: June 2010

The present study was undertaken to investigate physiological, metabolic, haematological and biochemical changes in horses competing in the Speed and Endurance test of a Concours Complet International (CCI) **** 3‐day‐event held under FEI rules. A total of 28 horses competing in the Burghley Horse Trials Speed and Endurance test were selected to be monitored: 11 horses in 1993 and 17 horses in 1994. Of the 28 horses selected, 17 completed the Speed and Endurance test and went on to complete the showjumping test. Mean ± s.d. shade temperature and relative humidity, black globe temperature and wind speed were 13 ± 1 and 20 ± 2°C, 54 ± 3 and 55 ± 10%, 17 ± 2 and 29 ± 4°C and 2.7 ± 0.7 and 1.2 ± 0.3 m/s, for 1993 and 1994, respectively. Mean heart rate duringPhases A, BandDwas not significantly different between years, but mean heart rate duringPhases CandXwas significantly higher in 1994. Mean (± s.d.) heart rate onPhases BandDfor all horses in both 1993 and 1994 was 198 ± 8 and 188 ± 11 beats/min, respectively. Mean heart rate duringPhase Dshowed a poor correlation with mean speed (r=0.412). Total mean (± s.d.) weight loss from the start ofPhase Ato the end ofPhase Dwas 15.5 ± 6.1 kg in 1993 and 16.5 ± 5 kg in 1994 and did not differ significantly between years. Following 14–18 h completion ofPhase D, mean bodyweight was not significantly different from that at the start ofPhase Ain either year. Mean rectal temperature at the end ofPhase Dwas 41 ± 0.6°C and 41.1 ± 0.6°C in 1993 and 1994, respectively (P>0.05). Both the lowest (39.7°C) and highest (41.8°C) rectal temperatures were recorded at the end ofPhase Din 1994. Plasma lactate concentrations at the end ofPhase Dwere 8.5–38.5 mmol/1. The highest lactate concentration also coincided with the highest plasma glucose concentration (11.4 mmol/1) as well as the joint fastest time in either year, although overall lactate showed only weak correlations with mean speed onPhase D(r=0.12, 1993; r=0.58, 1994). While the Speed and Endurance test at CCI**** level run in a temperate climate presents a considerable challenge to the fitness and ability of the horses competing, the metabolic and physiological changes are not extreme. The majority of horses that finish the test appear to undergo a rapid and considerable degree of recovery and are able to present sound at the final inspection, take part in the showjumping test and complete the competition.
Heart rate response and plasma lactate concentrations of horses competing in the cross‐country phase of combined training events
Authors: WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , COLE S. P. , ANDREWS E. M. , GEISER D. R.
Published: June 2010

The exercise intensity of horses (n=175) competing in the cross‐country phase of 4 combined training events at 5 levels of competition [novice (N), training (T), preliminary (P), intermediate (I) and advanced (A)] was investigated. Environmental conditions varied from cool and humid (mean ± s.d. temperature and humidity=12.1°C ± 0.6 and 88.4% ± 8.9 RH) to moderately hot and humid (27.8°C ± 2.1 and 62.5% ± 7.8 RH). Heart rates (beats/min) were recorded continuously at 5 s intervals with a heart monitor. Mean ± s.d. heart rates (beats/min) for each level of competition were: 154.4 ± 19.2 beats/min (n=45) (N), 160.4 ± 28.1 beats/min (n=47) (T), 160.6 ± 33 beats/min (n=53) (P), 181 ± 26.6 beats/min (n=29) (I) and 194.6 ± 4.2 beats/min (n=4) (A). Plasma lactate concentration was determined at rest in a random sampling of horses (n=36) from all competitions and within 60 s of completion of the cross‐country phase in all horses. Mean ± s.d. lactate concentration at rest was 0.98 ± 0.3 mmol/1. Mean ± s.d. lactate concentrations (mmol/1) of horses after exercise were: N=8.1 ± 7, T=11.5 ± 4.7, P=17.6 ± 6.1, I=19 ± 6.7 and A=21.3 ± 7.3. Mean plasma lactate increased significantly (P<0.001) as levels of competition increased, although there were few significant differences in heart rate between levels.

Rectal temperatures were taken immediately after completion of the cross‐country phase and 10 min later. Mean ± s.d. rectal temperatures were significantly higher 10 min after completion of the cross‐country than those taken immediately after cross‐country (P<0.001). Rectal temperatures 10 min after completion of exercise were significantly higher as the level of competition increased for N through I (P<0.001). Rectal temperatures 10 min after completion of exercise were correlated with ambient temperatures (r=0.22, P=0.01). There was no significant correlation between either pulse or respiratory rate taken immediately after completion of exercise with heart rate during the course.
Heart rate response and plasma lactate concentrations of horses competing in the speed and endurance phase of 3‐day combined training events
Authors: WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , COLE S. P. , ANDREWS F. M.
Published: June 2010

The exercise intensity of horses competing in 3‐day combined training events at 3 different levels of competition (CCI***, n=7; CCI**, n=11; CCI*, n=23) was investigated. Environmental conditions during all events were cool with 100% cloud cover. Heart rates were continuously recorded at 5 s intervals by a heart rate monitor. Mean ± s.d. heart rate for all horses during each phase were:Phase A=118 ± 11 beats/min,Phase B=179 ± 22.7 beats/min,Phase C=129 ± 13.9 beats/min andPhase D=174 ± 19.6 beats/min. Mean ± s.d. heart rates onPhases AandCwere significantly different from mean heart rates onPhases BandD.Plasma lactate concentrations were determined at rest, within 60 s and 10 min after the end ofPhase Dor the cross country test. Mean ± s.d. lactate concentrations were highest immediately post exercise (mean=18.4 ± 5 mmol/1 for all horses) and had declined significantly in 10 min (mean=15 ± 6.8 mmol/1 for all horses). Mean ± s.d. heart rates and lactate concentrations were not significantly different among levels of competition at each time period. The intensity of work of fit horses successfully competing in 3‐day combined training events consists of both low intensity aerobic exercise and more intense submaximal work with significant anaerobiosis. The work intensity is remarkably constant throughout different levels of competition, despite the increasing distance, number and difficulty of jumping efforts and faster optimum speeds.
Haematological and biochemical changes in horses competing in a 3 Star horse trial and 3‐day‐event
Authors: ANDREWS F. M. , GEISER D. R. , WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , GREEN ELEANOR M.
Published: June 2010

Haematological and biochemical changes in horses competing in the Endurance Test (Phase TandD) of an advanced Horse Trial (HT, n=22) and the Endurance Test (Phases A‐D) of an advanced (CCI***) 3‐day‐event (TD, n=11) over a similar course on the same day were studied. Environmental conditions during the event were cool (5.5–11.1°C). Blood samples were collected from the horses in each group the evening prior to the Endurance Test, within 60 s after, and 10 min after, completion ofPhase D(cross‐country jumping). The following were determined in the blood samples and compared between the 2 groups of horses: packed cell volume (PCV), serum total protein [TP], serum albumin [ALB], plasma lactate [lactate], serum total calcium [TCa], plasma ionised calcium [Ca++], serum inorganic phosphate [PO4], plasma pH, plasma sodium [Na], plasma potassium [K], serum chloride [Cl], serum urea nitrogen [SUN], serum creatinine [Cr] and serum glucose concentrations and aspartate aminotransferase (AST) and creatine kinase (CK) activities. The PCV and [Cr] were higher in the TD group and approached significance (P=0.063 and P=0.057, respectively). The [TP], [ALB], [Na], glucose concentration and CK, and AST were significantly higher and [Cl] and [PO4] were significantly lower in the TD group after exercise when compared to the HT group. It was deduced from these data that the horses competing in the 3‐day‐event experienced greater fluid and electrolyte losses, reduced glomerular filtration, higher glycogenolysis and had greater leakage of enzymes from working muscles during competition than horses competing in the horse trial.
Effects of shortening the steeplechase phase (Phase B) of a 3‐day‐event
Authors: ANDREWS F. M. , WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , GEISER D. R. , GREEN ELEANOR M. , RALSTON SARAH L. , MANNSMAN R. A.
Published: June 2010

Thirty‐four horses competing in the Endurance Test of a 3‐day‐event were divided into 3 groups: horses inGroup 1(n=15) competing in a 3.5 min steeplechase phase; horses inGroup 2(n=13) in a 3 min steeplechase phase (Phase B) and horses inGroup 3(n=6) in a 2.5 min steeplechase phase. The shortening ofPhase Bwas associated with a lengthening ofPhase Cso that the total distance of the event for all horses was 14,940 m. Bodyweight (BW) was measured and total body water (TBW) and water loss estimated. Blood samples were collected from the horses prior to the Endurance Test, at the end ofPhase B, the 4 km marker onPhase C(C4K), the end ofPhase C, and 20 min after the completion ofPhase Dfor measurement of packed cell volume (PCV), total plasma protein [TPP], lactate, ionised calcium, pH, sodium, potassium, chloride, total calcium and glucose concentrations, and aspartate aminotransferase, creatine kinase and lactate dehydrogenase activities. Mean ± s.d. ambient environmental temperature during the Endurance Test was 25.3 ± 1°C (range 20.3°C‐29.7°C). Mean relative humidity was 43.8 ± 2.4% (range 39%‐48.6%) and the average ‘comfort index’ (CI) was 121. There were no significant differences between the groups competing in the Endurance Test, despite the shorterPhase B.However, there were significant decreases in BW, TBW, net exchangeable cations, chloride, ionised calcium, and pH. The sodium and total calcium concentrations remained at near pre‐event values. The PCV, TPP, lactate, potassium, glucose, aspartate aminotransferase, and lactate dehydrogenase activity increased during the Endurance Test, when compared to pre‐event values. Horses competing in this competition experienced significant fluid and electrolyte losses, reduced glomerular filtration, increased glycogenolysis and had significant leakage of enzymes from working muscles during competition. These changes could not be reduced by shorteningPhase Band lengtheningPhase C.
Clinical observations made in nonheat acclimated horses performing treadmill exercise in cool (20°C/40%RH), hot, dry (30°C/40%RH) or hot, humid (30°C/80%RH) conditions
Authors: HARRIS PATRICIA A. , MARLIN D. J. , MILLS P. C. , ROBERTS C. A. , SCOTT C. M. , HARRIS R. C. , ORME C. E. , SCHROTER R. C. , MARR CELIA M. , BARRELET F.
Published: June 2010

Four horses (H, J, N and M) undertook a treadmill competition exercise test (CET), designed to simulate the physiological and metabolic stresses of the Speed and Endurance phase of a 3‐day‐event, under 3 different environmental conditions: 20°C/40% relative humidity (RH) (cool, dry [CD]: 2 sessions); 30°C/40% RH (hot, dry [HD]) and 30°C/80% RH (hot, humid [HH]) (Marlin et al. 1995). A number of subjective clinical observations were made at designated time points throughout the exercise test and initial recovery period including buccal mucous membrane colouration, capillary refill time, neck and point of shoulder skin pinch recovery time, grade of abdominal sounds; anal sphincter tone as well as the presence or absence of fatigue and ataxia. The aim was to investigate their value in predicting performance in the final canter phase of the CET equivalent to the cross‐country or Phase D of a field competition. In addition, the use of a more objective assessment, the cardiac recovery index (CRI), was investigated together with the heart rate, rectal temperature and respiratory frequency at the end of Phase C and at the 8 min point of the 10 Minute Box (8′X). The CRI was calculated according to the formula CRI = P2‐P1 where P2 = the heart rate in beats/min at the 8 min point of the ‘10 Minute Box’ (Phase X) of the CET. P1 = the heart rate (beats/min) at the 7 min point just before the horse was made to trot over a distance of 80 m at a speed of 3.7 m/s (at a 3° incline) before returning to a walk.

The study suggested that the subjective tests carried out at the ‘End‐C’ and/or ‘8′X’ time points were not useful in predicting subsequent performance in the final canter phase (Phase D) and neither were heart rate, rectal temperature or respiratory frequency. However, the only horse (Horse H) to complete the full CET under HH conditions was the only animal to show a decrease in respiratory frequency between the End‐C and 8′X time points. All others showed an obvious increase. Under HH conditions, Horse H also had the lowest CRI. For 3 of the horses the highest CRI value was found under the HH conditions, for the fourth horse an equally high CRI value was found with one of the CD sessions. However, under the HH conditions, both P1 and P2 values were >100.

The study suggested that it could be beneficial if a suitably modified CRI test, as well as a procedure to monitor the change in respiratory frequency during the 10 Minute Box, were evaluated further on the treadmill and in the field with respect to their potential usefulness as additional aids to the assessment of a horse's suitability to proceed to Phase D.
Thermal and cardiorespiratory responses of horses to submaximal exercise under hot and humid conditions
Authors: GEOR R. J. , McCUTCHEON L. J. , ECKER GAYLE L. , LINDINGER M. I.
Published: June 2010

The objective of this study is to determine the effects of heat, and heat and high relative humidity (RH) on the thermal and cardiorespiratory responses to exercise and recovery. Five Thoroughbred horses (age 3 to 6) completed exercise tests under each of 3 environmental conditions: cool, dry (CD, room temperature (T) = 20°C, RH = 45–55%), hot, dry (HD, T = 32–34°C, RH = 45–55%) and hot, humid (HH, T = 32–34°C, RH = 80–85%). Horses were exercised at a workload equal to 50% of V̇O2maxon a treadmill set at a 10% slope until attainment of a pulmonary artery blood (PA) temperature of 41.5°C followed by a 30 min walking recovery (0% slope), and a further 30 min standing recovery in the same environmental conditions. Blood (PA), rectal, skin (dorsal aspect of the thorax) and muscle (middle gluteal muscle) temperatures and heart rate were measured before, during and after exercise. Respiratory rate was measured before exercise and during the 60 min recovery period. Exercise duration for HD (mean ± s.e. 28 ± 2 min) and HH (16.5 ± 1 min) was significantly (P<0.05) decreased when compared with CD (37 ± 2 min). The rate of increase in PA blood temperature was significantly higher in HH (0.26 ± 0.03°C/min) than in HD (0.17 ± 0.04°C/min) and CD (0.12 ± 0.05°C/min). Temperature in the middle gluteal muscle after 15 min of exercise was significantly higher in HH (41.9 ± 0.3°C) than in HD (40.7 ± 0.25°C) and CD (40.15 ± 0.35°C); whereas rectal temperature at the end of exercise was significantly lower in HH (39.1 ± 0.3°C) than in HD (40.1 ± 0.3°C) and CD (40 ± 0.2°C). The PA blood:skin temperature difference was significantly smaller in HD and HH than in CD. When compared with CD, temperatures at all sites were higher in HD and HH during the 60 min of recovery. Throughout exercise and recovery, heart rate was significantly higher in HH when compared with the other conditions. Post exercise respiratory rate was significantly higher in HD and HH than in CD throughout recovery. It was concluded that the added thermal loads of high temperature and relative humidity increased the rate of heat storage during exercise and delayed dissipation of heat during recovery. The impairment to heat dissipation was probably the result of a reduced capacity for heat transfer from the skin to the environment.
Elemental composition of muscle at rest and potassium levels in muscle, plasma and sweat of horses exercising at 20°C and 35°C
Authors: GOTTLIEB‐VEDI M. , DAHLBORN K. , JANSSON A. , WROBLEWSKI R.
Published: June 2010

In this study, 4 Standardbred geldings were exercised at 20 and 35°C. The exercise test (ET) consisted of 2 exercise bouts separated by 2 h of rest in their boxes. Blood samples were taken before, during and after the second exercise bout and muscle (m. gluteus medius) biopsies were taken before the first exercise bout and after an intensive trot over 2600 m in the second exercise bout. The blood samples were analysed for plasma potassium and total plasma protein concentration (TPP) and the muscle fibres were analysed for elemental composition by x‐ray microanalysis. The intracellular content was as follows: sodium (Na) = 40 ± 7; magnesium (Mg) = 32 ± 4; phosphorus (P) = 282 ± 15; sulphur (S) = 222 ± 13; chloride (Cl) = 119 ± 31; potassium (K) = 304 ± 21 and calcium (Ca) = 8 ± 2 mmol/kg dry weight under resting conditions. Intracellular potassium content increased after exercise compared to resting values. There was a good correlation between exercise intensity, plasma potassium concentration and shifts in plasma volume, indicated by alterations in TPP. This probably reflects the very fast shift of potassium and fluid between muscle and plasma. Plasma potassium concentrations decreased below resting values post exercise. The higher dehydration degree and potassium sweat loss after exercise at 35°C was not reflected in lower muscular potassium content, but by a lower plasma potassium/total plasma protein ratio after exercise, indicating less circulating potassium.
Acid‐base and electrolyte effects of shortening steeplechase in a Three‐day‐event
Authors: FOREMAN J. H. , GRUBB T. L. , BENSON G. J. , FREY L. P. , FOGLIA R. A. , GRIFFIN R. L.
Published: June 2010

This study was designed to characterise the acid‐base and electrolyte effects of shortening the distance required during steeplechase (Phase B) in the face of hot and humid weather conditions during a treadmill‐simulated Speed and Endurance test.

Eight conditioned Thoroughbred horses underwent 3 randomised permutations of a standardised exercise test on a high speed treadmill. Each test consisted of trotting at 3.7 m/s for 10 min (Phase A); galloping at 11 m/s (Phase B) for 4 (cool laboratory conditions), 3 (hot and humid), or 2 (hot and humid) min; trotting at 3.7 m/s for 30 min (Phase C); and walking at 1.8 m/s for 10 min (Phase X). The treadmill slope was 4% for trotting and galloping and 0% for walking. Cool versus hot and humid conditions were 20°C and 50–60% relative humidity vs. 26–28°C and 80–85% relative humidity, respectively.

Pulmonary artery blood samples were obtained at rest prior to exercise (Rest); at the end ofPhases A(A10) andB(B2‐4); at 10 (C10), 20 (C20) and 30 (C30) min throughPhase C; and at 5 min intoPhase X(X5). Additional samples for lactate (LA) and glucose (GLC) analysis were obtained 5 min intoPhase C(C5) and at the end ofPhase X(X10). Samples were analysed for packed cell volume (PCV), haemoglobin (HB), total plasma protein (TP), sodium (Na), potassium (K), chloride (Cl), anion gap (AG), plasma glucose (GLC) and lactate (LA), pH, PCO2, bicarbonate (HCO3) and base excess (BE).

Shortening steeplechase distance by 50% under hot and humid conditions (2 min B) resulted in a consistent return to control measurements (4 min B) only for plasma LA. Changes in PCV, HB, TP, K and Cl were related more to the longer galloping distance in the 4 min B trials than to hot vs. cold laboratory conditions. Alternatively, changes in LA, GLC, pH, PCO2and AG were more related to hot and humid laboratory conditions than they were to galloping distance. These latter variables, when combined with physical measures such as core temperature, bodyweight loss, point of fatigue onPhase Cand recovery heart rates may serve as the best monitors of positive responses in future studies of proposed modifications toPhase C, rather than those variables which were more distance than weather‐related.
Ground reaction forces in horses, assessed from hoof wall deformation using artificial neural networks
Authors: SAVELBERG H. H. C. M. , VAN LOON T. , SCHAMHARDT H. C.
Published: June 2010

An artificial neural network (ANN) was developed to investigate whether hoof wall deformation could be used to determine ground reaction forces (GRF) in horses. The ANN was taught this relationship under certain conditions and was able to generalise this knowledge to conditions for which it was not trained before.

To acquire data to train and test the ANN, a horse was equipped with strain gauges attached to the dorsal, lateral and medial parts of the hoof to assess hoof wall deformation. A force plate was used to measure the GRFs. Both hoof wall deformation and GRF were recorded simultaneously at different speeds, gaits, surfaces and loads. An ANN was trained with some of these data, and subsequently provided with strain gauge recordings of strides, not used for training. By comparing the GRF calculated by the ANN based on the hoof wall deformation with that recorded simultaneously by the force plate, the generalisability of the ANN was determined. It was found that an ANN is capable of ‘learning’ the relationship between hoof wall deformation and GRF, and to generalise it to a wide range of new conditions. This technique enables assessment of GRF under difficult conditions, such as on a treadmill or on surfaces where a force plate cannot be employed.
Radiological assessment of the effects of a full rolling motion shoe during asymmetrical bearing
Authors: CAUDRON I. , MIESEN M. , GRULKE S. , VANSCHEPDAEL P. , LEROY P. , SERTEYN D.
Published: June 2010

The authors used a new radiological method to assess asymmetrical articular compression of the interphalangeal joints. This method was based on the measurements of 3 angles obtained on dorsopalmar radiographs. Variations of these angles were studied during experimental asymmetrical bearing on unshod feet. It was concluded that 2 angles were interesting parameters to assess asymmetrical articular compression and to define the position of the phalanx in the horny box. Furthermore, variations of these angles induced by experimental asymmetrical bearing were compared without shoe, with a standard shoe and with an orthopaedic full rolling motion shoe. It was observed that the effects of the asymmetrical bearing were reduced when feet were shod with a full rolling motion shoe.
Model for injury to the foreleg of the Thoroughbred racehorse
Authors: PRATT G. W.
Published: June 2010

A discussion is presented of contributing factors to the injury to the foreleg of the Thoroughbred racehorse. The critical part of the step is taken to be the first 10–20 ms after ground contact as the hoof slides forward and stops. Large nonaxial loads associated with the deceleration of the hoof are shown to arise. Results of accelerometer measurements on the hoof of a horse running at racing speed are presented as well as mechanical properties of the racing surface. The mechanical properties of the track surface, the type of shoe, and the degree of fatigue of the horse all work together to determine the level of risk.
Joint moments and power in equine gait: a preliminary study
Authors: COLBORNE G. R. , LANOVAZ J. L. , SPRIGINGS E. J. , SCHAMHARDT H. C. , CLAYTON HILARY M.
Published: June 2010

A method is described for the estimation of joint moments of force and power in the equine forelimb using S‐VHS video and force platform data. Video and force data were collected for 5 walking trials in a sound Dutch Warmblood horse. The sagittal plane positional and angular data were combined with the vertical and cranio‐caudal ground reaction forces to calculate net joint moments of force in the sagittal plane across the carpal, fetlock and coffin joints during the stance phase of the forelimb. The mechanical power was calculated as the product of the net joint moment and the joint's angular velocity. The carpus demonstrated oscillating periods of energy generation and absorption in early stance against a flexor moment, then an absorption phase at the end of stance as the carpus flexed against an extensor moment. The fetlock absorbed energy in early stance as it flexed against an extensor moment, then showed short periods of positive and negative work in mid‐stance. Energy was generated across the fetlock as it extended for push‐off. An extensor moment was measured at the coffin joint through most of stance, and this coincided with a phase of energy absorption followed by a longer phase of generation. In terminal stance, a flexor moment was produced and this was accompanied by a period of generation for push‐off.
Power flow in the equine forelimb
Authors: COLBORNE G. R. , LANOVAZ J. L. , SPRIGINGS E. J. , SCHAMHARDT H. C. , CLAYTON HILARY M.
Published: June 2010

A method is described for the estimation of segmental powers and power flow during the stance phase in the equine forelimb, to demonstrate the sources and paths of energy flow through the limb segments. S‐VHS video and force platform data were collected for 5 walking trials in a sound Dutch Warmblood horse. Two camera views were combined using direct linear transformation and the resultant sagittal plane positional and angular data used together with the vertical and cranio‐caudal ground reaction forces to calculate moments about the ends of the 4 lowermost segments of the forelimb, and the reaction forces at the segment ends. Power flows were calculated across the proximal and distal ends of each segment and total segmental power computed. During initial and terminal stance, power flowed into the cannon segment proximally, and out distally. For the rest of stance, the flow in the cannon was distal to proximal. At the pastern, power flowed in proximally during initial loading, and out distally. For most of the rest of stance, the pattern of flow was distal to proximal, except for terminal stance, when power flowed in through both ends. The largest effect at the hoof is a loss of energy in terminal stance as power flowed out proximally and into the pastern. The pastern appears to receive most of the energy during loading and pushoff and transfers this energy up the limb during midstance.
Effect of added weight on landing kinematics in jumping horses
Authors: CLAYTON HILARY M.
Published: June 2010

Six event horses jumped a 1.10 m high table fence 4 times under each of 2 conditions; the rider weight condition involved carrying the weight of the rider and saddle (61 kg), whereas the added weight condition included an additional 18 kg weight cloth. Sagittal view, 60 Hz video recordings were analysed using standard methods. Comparisons between the rider weight and added weight conditions using pairedttests (P<0.05) showed a number of significant differences. In the added weight condition the leading forelimb landed closer to the fence, and there were increases in the maximal extension of the fetlock and carpal joints in this limb during the landing phase. In the first departure stride, the stance durations of both hindlimbs increased, and the advanced placement between them was reduced for the added weight condition. The head was significantly further ahead of the vertical in the added weight condition at the instants of ground contact of the TrH, LdH and TrF in the first departure stride.
Effects of trot quality and collection on the angular velocity in the hindlimbs of riding horses
Authors: HOLMSTRÖM M. , DREVEMO S.
Published: June 2010

The angular velocities of the hindlimb angles of 14 horses, including 6 Grand Prix dressage horses, 4 horses judged as good at the trot and 4 horses judged as poor, were analysed. The horse material was the same as previously used by Holmström (1994) in studies on conformation and trotting gaits in the Swedish Warmblood riding horse. Four consecutive strides of each horse and the corresponding pace were analysed and mean velocity curves (Xh) for each angle were calculated. Before calculation the data were filtered forwards and backwards with a Butterworth third order filter with a cut off frequency of 60 Hz. During the last 60% of the stance phase there were differences between the horses judged as good and poor at the trot in all the analysed hindlimb angles except the femur inclination. The angular velocity in the hock joint, pelvis inclination and hindlimb pendulation was larger in the good horses. The angular velocity of the hindlimb pendulation decreased with collection in the Grand Prix horses. During parts of the stance phase, there was also a gradual decrease in the femur angular velocity from trot at hand to piaffe. In the hock joint, there was no difference in angular velocity between trot at hand and passage during the last 30%. The higher compression of the hock angle and pelvic angle to the horizontal plane probably reflects a higher compression of the whole hindlimb. It probably contributes to the greater springiness in the movements of good young horses and Grand Prix dressage horses. The results from the present study confirmed the importance of storing elastic strain energy for the quality of the dressage horse gaits.
Effects of treadmill inclination on kinematics of the trot in Dutch Warmblood horses
Authors: VAN OLDRUITENBORGH‐OOSTERBAAN MARIANNE M. SLOET , BARNEVELD A. , SCHAMHARDT H. C.
Published: June 2010

To evaluate the effects of uphill trotting on stride characteristics, 6 well trained Dutch Warmblood horses trotted at 4 m/s on a horizontal and on an inclined (6%) treadmill. This was done under 3 different conditions, unloaded, mounted by an experienced 90 kg rider and loaded with 90 kg of lead, to study whether extra weight provoked more or different alterations than the incline per se. In all 3 test situations (unloaded, mounted and lead‐loaded), heart rates were significantly higher on the inclined treadmill than on the horizontal treadmill. Stride duration tended to increase on the inclined treadmill. Stance duration increased significantly on a slope, more in the hindlimbs than in the forelimbs. In the unloaded condition, maximal fetlock extension of the forelimb decreased on the incline, whereas maximal fetlock extension of the hindlimb and tarsal range of motion increased significantly on the slope in all 3 conditions.

The overall effect was that on an inclined treadmill the hindlimbs seemed to carry more weight (higher maximal fetlock extension), and to provide greater propulsion (higher tarsal flexion and increased pro/retraction).
Kinematics and kinetics of the carpus
Authors: JOHNSTON C. , DREVEMO S. , ROEPSTORFF L.
Published: June 2010

This study investigated the kinematics and kinetics of the carpus during the stance phase. Five Standardbred horses trotted on a treadmill at 8.9 m/s. The kinematics of the horses were filmed and hoof reaction forces (HRF) were recorded. The carpus was overextended throughout most of the stance. There were 2 periods of overextension, a more rapid period in the beginning of the stance and second directly following the first period. Maximal overextension occurred slightly before the second minimum of the braking horizontal HRF. The metacarpal and antebrachial segments rotated counterclockwise for most of the stance. The angular velocities of these segments attained absolute and local extremes that were concurrent. The absolute maxima in the longitudinal and the transversal acceleration of the proximal metacarpus were coincident in time with the minimal horizontal braking force. The moment of force about the carpus was extending throughout most of the stance, with a short period of flexion near the end of the stance. The results show that horizontal braking of the hoof results in impulsive loading followed by maximal overextension of the carpus. The second phase of overextension is suggested to be related to the tension or active roll of the flexor tendons of the distal limb. The carpus is, therefore, subjected to rapid and high loading in both the longitudinal and transversal directions, as well as large moments and forces.
Investigating locomotion of dairy cows by use of high speed cinematography
Authors: HERLIN A. H. , DREVEMO S.
Published: June 2010

The longterm influence of management systems on the locomotion of 17 dairy cows was investigated by high speed cinematography (100 frames/s) and kinematic analysis. Angular patterns and hoof trajectories of the left fore‐ and hindlimbs are presented and statistics made of occurring minimum and maximum angles. At the recording, 3 cows had been kept in tie‐stalls (TI) and 6 cows in cubicles (CI) for a consecutive time of about 2.5 years while 8 cows had been kept on grass for about 3 months. Four of the grazing cows had earlier been kept in cubicles (CG) and 4 in tie‐stalls (TG) during earlier off grazing seasons together with TI and CI cows. The CI cows had a smaller maximum angle of the elbow joint compared to TI, TG and CG cows. The hock joint angle of the CI cows was less flexed during the stance phase than in TI and CG cows while the minimum angle during the swing phase was greater in the TI and CI cows compared to TG and CG cows. Pastured cows (TG and CG) had a less pronounced flexion of the fetlock joint angle during the stance compared to cows kept indoors (TI and CI). The results suggest that slatted floor and lack of exercise during summer grazing may affect locomotion. This is indicated by restrictions in the movements of the elbow and hock joints and in less fetlock joint flexion at full support.
Aspects of autonomic and neuroendocrine function
Authors: EDWARDS A. V.
Published: June 2010

This article provides a brief review of aspects of autonomic and neuroendocrine function studied initially in collaboration with the late Marian Silver. The importance of the sympathetic innervation to the liver in the control of glycogenosis was established in anaesthetised animals of various species. Otherwise the work has been carried out mainly in conscious animals under strictly physiological conditions and below behavioural threshold.

Investigations of the role of the autonomic innervation to the endocrine pancreas in controlling the release of pancreatic hormones, led to the realisation that the parasympathetic innervation mediates reponses to glycaemic stimuli while the sympathetic innervation mediates responses to any form of stress. Studies of adrenal medullary function have confirmed that its threshold for many forms of stress is much higher than that of other components of the sympathetic system and revealed the importance of the pattern of electrical stimulation in determining the rates of release of catecholamines, enkephalins, corticotrophin‐releasing factor (CRF) and adrendocorticotrophin (ACTH). The splanchnic sympathetic innervation to the adrenal cortex also plays an important role in determining glucocorticoid output by sensitising the cells to ACTH, probably mainly by the release of vasoactive intestinal peptide (VIP) from cortical nerve terminals. Finally studies of feeding in milk‐fed calves have shown that suckling is associated with a remarkable hypertension and tachycardia. These cardiovascular effects are due to a selective sympathetic discharge, which does not involve the adrenal medullae, or the release of neuropeptide Y (NPY) and, at least in the calf, can be attributed to activation of adrenoceptors.
Follicular fluid is not a compulsory carrier of the oocyte at ovulation in the mare
Authors: PALMER E. , DUCHAMP G. , CRIBIU E.P. , MAHLA R. , BOYAZOGLU SONIA , BÉZARD JACQUELINE
Published: June 2010

The aim of this study was to test the possibility that ovulation can occur from a preovulatory follicle emptied of its follicular fluid. Transport of the oocyte into the oviduct and fertilisation in 29% of cases demonstrated that ovulation can occur in the absence of follicular fluid but the higher fertility achieved in control mares (62.5%) suggested that follicular fluid does serve a role during ovulation, fertilisation and oviductal transport. Injection of horse oocytes into preovulatory follicles in mules after removal of the follicular fluid, followed by insemination of the mules with horse semen, resulted in the production of one horse x horse embryo.
Equine oocyte‐cumulus morphology as affected by follicular size
Authors: MLODAWSKA W. , OKÓLSKI A.
Published: June 2010

From the ovaries of 256 slaughtered mares a total of 1713 follicles were isolated from which 1641 (95.8%) oocytes were recovered (6.4/mare). A total of 564 follicles and oocytes were evaluated for the degree of vascularisation of the follicle wall, the appearance of the follicular fluid and the location and morphology of the cumulus‐oocyte‐complex. Follicles with a diameter of >10 mm displayed more numerous, well branched and more pronounced blood vessels than the smaller ones (4–10 mm diameter) and most of them contained clear, yellowish fluid with few granulosa cells. The percentage of oocytes with compact cumuli increased significantly with an increasing diameter of the follicle, being 233%, 43.9%, 55.6% and 64.2% (P < 0.01) for the follicles with diameters of 4–10, 11–15, 16–20 and 21–35 mm, respectively. The percentage of oocytes attached to the follicle wall also increased with increasing follicle size, being 48.0%, 59.6%, 81.5% and 90.1% (P < 0.01), respectively. On the contrary, the percentage of oocytes floating in the follicular fluid decreased with increasing follicle diameter, from 52.0% in the smallest follicles to 9.9% in the biggest ones. A significantly greater percentage of oocytes found on the follicular wall than in the follicular fluid had a compact cumulus (56.6 versus 213%; P < 0.01). Forin vitroculture were accepted 30.4%, 54.3%, 60.7% and 77.8% (P < 0.01) of oocytes from the follicles with diameters of 4–10, 11–15, 16–20 and 21–35 mm, respectively. After culture for 28–40 h in TCM 199 medium, 90 of a total of 165 (54.5%) oocytes reached the metaphase II stage of maturation.
Treatment of equine oocytes with A23187 after intracytoplasmic sperm injection
Authors: KATO H. , SEIDEL G. E. , SQUIRES E. L. , WILSON J. M.
Published: June 2010

In vitro matured horse oocytes with a first polar body (n = 68) were each injected with a single spermatozoon and divided into 2 groups: Group 1 oocytes were treated with 10 μM calcium ionophore A23187 for 5 min while Group 2 oocytes received no activation treatment. After culture in vitro for 2 days, significantly more oocytes treated with A23187 (5/24, 21%) cleaved than oocytes without activation treatment (2/44, 5%, P < 0.05). All 7 cleaved zygotes from both treatment groups were transferred to recipient mares but no pregnancies resulted.
Spontaneous multiple ovulation and development of multiple embryonic vesicles in a mare
Authors: BRÜCK INGRID , LEHN‐JENSEN H. , YDE G.
Published: June 2010

A Warmblood mare was observed to ovulate spontaneously 12 follicles within 2 days, none of which exceeded 22 mm in diameter. On Days 13 and 17 after ovulation, 6 embryonic vesicles were identified in the uterus by ultrasonography but by Day 26, 5 of the vesicles had disappeared. Development of the surviving conceptus was monitored until Day 42. Plasma progesterone concentrations rose to 14 ng/ml on Day 7, decreased over the next 8 days and then plateaued to around 4–6 ng/ml until Day 70. The occurrence of multiple spontaneous ovulations was diagnosed repeatedly in this mare. However, the developmental competence of the ovulated oocytes seemed to be impaired.
The use of early pregnant mares as embryo recipients
Authors: CAMILLO F. , CELA M. , VANNOZZI I. , ROMAGNOLI S. , ARIA G.
Published: June 2010

Fourteen normal, cyclic mares, treated to synchronise oestrus and ovulation and inseminated artificially with fresh semen, were assigned to a donor or a recipient group after ovulation, with the aim of obtaining a degree of synchrony of >2 days. Ten embryos, collected on Day 6 or 7 after ovulation (Day 0), were transferred nonsurgically to inseminated recipient mares (IRM) that had ovulated up to 5 days after the respective donors, or to pregnant recipient mares (PRM) that had ovulated 2–7 days before the donors. Embryonic size and development, as determined by ultrasound examination, were used to distinguish embryos derived from the recipient (recipient embryo = RE) or from the donor (transferred embryo = TE) mare. In cases of twin pregnancy, the RE was manually squeezed on Days 14–16. Abortion was induced in all mares on Day 30.

Three of 6 TE developed in IRM. Two of 6 IRM developed a twin pregnancy (RE+TE), while 4 of 6 IRM developed a singleton pregnancy (1 TE and 3 RE). None of 4 TE developed in Day 9–14 PRM and one of these PRM lost her own embryo following ET. The experiment demonstrated that a mare can carry her own embryo and a transferred embryo simultaneously. However, the status of pregnancy does not improve conception rate in recipient mares that ovulate prior to the donor.