bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of ambient temperature and saline loading on changes in plasma and urine electrolytes (Na+and K+) following exercise
Authors: JANSSON ANNA , NYMAN S. , MORGAN K. , PALMGREN‐KARLSSON C. , LINDHOLM A. , DAHLBORN K. 
Published: June 2010

SummaryIn this study 4 Standardbred geldings (age 3–8 years, weight 431–531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed.Phase 1consisted of 23.5 min of mainly submaximal exercise,Phase 2of 2 h of box rest andPhase 3of 26 min of exercise including an intensive trot over 2600 m at 90% of V̇O2max. The ET was repeated 3 times: the first at 20°C (30–40% RH), the second at 35°C (30–40% RH) and the third at 35°C (30–40% RH) after a nasogastric administration of 10 litres of 0.9% NaCl solution (35°C and saline load [+ F]). Blood samples were taken before, during and after exercise. To measure fluid loss, horses were weighed before and after the ETs. Total urine output was determined 2 days before the ET (control), throughout the exercise day and for 2 days after (recovery days). There were an increase in blood and rectal temperatures after both exercise phases and a significant higher blood temperature was observed after exercise at 35°C compared to 20°C. The horses lost about 2% of their bodyweight (bwt) during the ETs. The plasma protein concentration increased during the exercise phases and remained elevated 2 h after exercise at both 20°C and 35°C, even though the horses had free access to water. The plasma protein concentration had returned to pre‐exercise levels 26 h post exercise. After the saline load, total plasma protein concentration fell and increased only at the end of each exercise phase. The major mechanism regulating fluid balance after exercise seemed to be a lowered urinary excretion since water intake did not increase significantly. Urinary potassium excretion was positive throughout the experiment. During control days there was a positive sodium balance, shown by a urinary sodium excretion of 260 mmol/day. Post exercise urinary sodium excretion fell and remained very low until the second day of recovery, except after saline loading. In addition, plasma sodium was lowered 26 h after exercise at 35°C.This study shows that with a daily salt intake of 38 g it will take several days to compensate for a sodium loss caused by sweating. Therefore, it is recommended that extra salt be given during the exercise day. In the experimental situation, pre‐exercise saline supplementation was beneficial since the recovery time was shortened.
Equine sweat composition: effects of adrenaline infusion, exercise and training
Authors: McCONAGHY FINOLA F. , HODGSON D. R. , EVANS D. L. , ROSE R. J. 
Published: June 2010

SummarySignificant alterations in plasma electrolyte concentrations have been reported in horses following prolonged exercise, resulting from loss of hypertonic sweat. Sweat was collected from 10 horses undergoing a 10 week training programme; 5 at moderate intensity, to speeds of 10 m/s and 5 at low intensity, to speeds of 5 m/s. Sweat was collected from 2 sites in response to a submaximal exercise test (30 min at 50% V̇O2maxand during an adrenaline infusion (dose mean ± s.d.; 0.3 ± 0.05 g/kg over 30 min). Sweat samples were analysed for sodium, chloride, potassium, protein, magnesium, calcium and urea concentrations. Sweat produced in response to exercise and adrenaline infusion was hypertonic and showed no significant differences in composition following training. However, the [NaCl] of sweat rose with increased duration of sweating. Sweat produced in response to adrenaline infusion was more dilute than that produced in response to exercise, which may be related to sympathetic outflow during exercise.
Integrative model for predicting thermal balance in exercising horses
Authors: MOSTERT H. J. , LUND R. J. , GUTHRIE A. J. , CILLIERS P. J. 
Published: June 2010

SummaryA theoretical integrative model was developed to determine the heat balance of horses working in a given environment. This model included the following parameters: metabolic heat gain, solar heat gain, evaporative heat loss due to sweating, respiratory tract heat loss, radiation from the body and heat gain or loss due to convection and conduction.The model developed in this study includes an unique approach for estimating heat loss via evaporation of sweat from the animal's skin surface. Previous studies modelling evaporative heat dissipation were based on the volume of sweat loss. While it is known that the ambient conditions affect evaporation rate, these effects have not been adequately described. The present model assumes the horse's skin surface is adequately represented by a body of water and it describes the interaction of that water body with the atmosphere.It is assumed that sweat has thermodynamic characteristics equivalent to distilled water. Sweat, however, has high electrolyte and protein concentrations and anecdotal evidence has shown that the thermodynamic characteristics may be significantly affected. Further research is, therefore, required to confirm these characteristics for equine sweat.The model describes all factors known to affect the thermal balance of the horse working in a given environment. The relative significance of the various variables on the whole integrative model has been illustrated. The effect of ambient temperature and humidity on the evaporative heat loss, the most significant and critical avenue of heat dissipation, is defined and quantified. The model illustrates clearly how increasing relative humidity limits evaporative heat loss, which can be further compromised when horses exercise on treadmills with no air movement.
Gait, estimated net cost of transport and heat production at different speeds in Three‐day‐event horses
Authors: SCHROTER R. C. , BAYLIS E. , MARLIN D. J. 
Published: June 2010

SummaryHeart rate and gait characteristics (stride length and frequency) were studied in 6 horses subjected to a standardised incremental exercise test, involving moving at the trot and increasing speeds up to a fast gallop and subsequently during the steeplechase phase of a 3‐day‐event. The studies were performed in hot conditions. Appropriate scaling, based on hindleg length (hh), stride length (L), stride frequency (f) and speed (Sp) for nondimensional stride length (Λ = (L/hh), nondimensional stride frequency (φ = f(hh/g)1/2) and nondimensional velocity (û = Sp/(ghh)1/2), wheregis the gravitational acceleration, demonstrated that there were no major differences in characteristics over the full range studied Λ = 2.3 û0.68. However, there were subtle differences in some horses that could endow a benefit in locomotory efficiency when compared to others exercising at the same absolute speed. There were clear changes in the relationship between nondimensional stride length and frequency with increasing speed, from trot to canter (at û ⋍ 1.4) and to full gallop (at û ⋍ 2.3); when trotting, Λ was less than 2.2 and the transition from canter to gallop took place at Λ ⋍ 3.2.The cost of transport/kg/m, estimated from the heart rates measured continuously during each study, decreased with increasing speed and bodyweight. In some animals, there appeared to be a weak minimum around the canter‐gallop transition speed. When interpreted as oxygen cost, using published values for the oxygen consumption‐heart rate relationship, the cost fell from an average of 0.201 ml/kg/m at the trot to 0.161 mlO2/kg/m when galloping during the incremental exercise tests. During the steeplechase, the cost was approximately 7.5% higher than at the same speed in the exercise tests; this was probably due to jumping effort.Estimated power consumption increased linearly with speed. In the steeplechase, power consumption was also 7.5% higher than during the exercise tests at the same absolute speed; this was equivalent to an average rate of heat production of 346 kcal/min (24 kW) or 59.5 kcal/min/m2of the measured body surface area.
Restoration of water and electrolyte balance in horses after repeated exercise in hot and humid conditions
Authors: HYYPPÄ S. , SAASTAMOINEN M. , PÖSÖ A. R. 
Published: June 2010

SummaryNine adult riding horses performed on a treadmill a competition exercise test (CET) and 24 h later a standardised exercise test (SET) at mean temperature 28°C and relative humidity 58%. Each horse performed the tests 5 times at 2 week intervals. The horses were given isotonic glucose‐electrolyte solution via a nasogastric tube 30 min after the CET, except after the last trial when water was given. Blood lactate, plasma concentration of aldosterone, arginine vasopressin, protein, sodium, potassium, chloride, magnesium and calcium were measured. Heart rate at blood lactate concentration 4 mmol/l (PLa4) in the SET, plasma volume (PV) and red cell volume (CV) were determined. Mean weight loss after CET was 3.1% and did not change significantly during the study. Bodyweight loss (BWL2) before SET (−1.8% after the first trial) decreased linearly with time (P<0.05) and was −0.8% after the fourth trial. After the fifth trial, when only water was given, the weight loss was −2.5%. PLa4correlated significantly (P<0.001) with BWL2when BWL2was greater than −1.2%. The horses acclimated to exercise in hot and humid conditions as indicated by better recovery of bodyweight, increased PV, lower peak lactate concentrations and heart rate and attenuated decrease in the concentrations of sodium and chloride.It is concluded that changes in bodyweight provide a good indication of recovery of horses after exercise in hot and humid conditions; and administration of an isotonic glucose‐electrolyte rehydration solution after exercise helps to overcome dehydration better than water alone.
Recovery of equine forelimb function after desmotomy of the accessory ligament of the deep digital flexor tendon
Authors: SAVELBERG H. H. C. M. , BUCHNER H. H. F. , BECKER C. K. 
Published: June 2010

SummaryThe recovery process of the equine locomotor system after desmotomy of the accessory ligament of the deep digital flexor tendon (AL‐DDFT) was investigated by studying the movement patterns and joint moments in 6 horses before and 10 days and 6 months following surgery.Using a modified CODA‐3 system the joint angles and angular velocities of the lower limb were assessed in the operated forelimb as before the operation. Simultaneously ground reaction forces were measured and joint moments calculated. At 10 days and 6 months after the operation the carpal joint started to bend earlier in the stance phase. At that instant, the fetlock joint was more extended and displayed a higher angular velocity. The moment of the coffin joint was significantly decreased 10 days after desmotomy. After 6 months it had recovered considerably, but still the shape of the curve was significantly different compared to that before the operation. The fetlock joint moment was not affected, but turned out to be generated for a greater part by the suspensory ligament and the superficial digital flexor 10 days after the operation.Further analysis of these results showed that 6 months after the desmotomy the locomotor system was able to cope with almost similar external moments. To accomplish this, it had adopted a new co‐ordination pattern during the recovery process.
Kinematic comparison of the leading and trailing fore‐ and hindlimbs at the canter
Authors: BACK W. , SCHAMHARDT H. C. , BARNEVELD A. 
Published: June 2010

SummaryThe canter is a 3 beat asymmetrical gait with a difference in timing between left and right limbs. To evaluate intralimb asymmetry at the canter, a group of 24 Dutch Warmbloods was evaluated on a treadmill (7 m/s) using a modified CODA‐3 optoelectronic gait analysis system. Thirteen horses cantered in the left lead (‘leading limb’ group) and 11 in the right lead (‘trailing limb’ group) during left forelimb recordings, while 11 horses were at the left and 13 were at the right lead during left hindlimb recordings. Kinematic differences between horses from the ‘leading limb’ and ‘trailing limb’ group were statistically evaluated at a significance level of P<0.05.Stride, stance and swing duration were similar between the 2 groups. The pelvis rotation, angle of maximal protraction and total range of maximal pro‐ and retraction were larger in the ‘leading limb’ group, while the scapula rotation, and the angle of maximal retraction were larger in the ‘trailing limb’ group. The elbow and hip joints were more flexed at impact, at maximal extension and at maximal flexion of the leading limb, whereas the stifle joint was more extended at impact. Furthermore, the leading tarsal joint was more maximally flexed in stance and swing phase, whereas the carpal joint was more flexed only in the swing phase of the leading limb. However, during the stance phase the maximal fetlock extension of the trailing fore‐ and hindlimbs were significantly larger.Apparently, horses move at the canter with a more protracted leading limb by more flexing the elbow, carpal, hip and tarsal joints. In the trailing limb, however, the scapula is more rotated, and the tarsal and fetlock joints are more loaded. In conclusion, the difference in interlimb timing between left and right limbs at canter also leads to an asymmetry in intralimb coordination of these limbs.
Variability of the limb joint patterns of sound horses at trot
Authors: DEGUEURCE C. , POURCELOT P. , AUDIGIÉ F. , DENOIX J. M. , GEIGER D. 
Published: June 2010

SummaryThe reproducibility of gait variables for sound horses is essential for the interpretation of their modifications by locomotor disorders. Therefore, the purpose of this study was to evaluate the variability of the limb joint angle patterns in a population of sound horses while they trotted in the conditions of the routine lameness examination (slow trot, just held by hand, on a track, outdoors). The kinematics of 14 French Saddle horses was recorded using a 3‐dimensional (3D) kinematic analysis system. Angle‐time diagrams were established in the sagittal plane and their intra‐ and inter‐individual variabilities were evaluated for the whole stride.Horses spontaneously repeated tests at constant speed. The intra‐ and inter‐individual variabilities were low. These values were different from one joint to another and they increased distally. The maximum values were reached by the fetlock and coffin joints. Inter‐individual compared to intra‐individual variability was 0.9 to 1.9 times greater. There was a high correlation between mean angle‐time and mean individual diagrams established for the whole population.It was concluded that it is possible to repeat similar tests with horses trotting in the conditions of the lameness examination. In an homogeneous population, each horse adopts a constant angular pattern that is very close to that of other horses. Since mean angle‐time diagrams established on a sound population are highly representative of each mean individual angle pattern, they can be considered as reference data for the further analysis of the pathological gait.
Compensatory movements of horses with a stance phase lameness
Authors: UHLIR CLAUDIA , LICKA THERESIA , KÜBBER P. , PEHAM C. , SCHEIDL M. , GIRTLER D. 
Published: June 2010

SummaryIn order to study the mechanism of lameness transfer from fore‐ and hindlimb lamenesses 2 hypotheses were investigated. Hypothesis 1: Horses with a true supporting limb lameness in one hindlimb show a false supporting limb lameness in the ipsilateral forelimb. Hypothesis 2: Horses with a true supporting limb lameness in one forelimb show a false supporting limb lameness in the contralateral hindlimb.Fourteen horses with fore‐ or hindlimb lameness were used for this study. Each horse was measured at the trot on a treadmill with standardised speed, before and after diagnostic blocks (9 horses), or with and without induced lameness (5 horses). The head acceleration asymmetry (HAAS) and the sacrum acceleration asymmetry (SAAS) were used for quantification of fore‐ and hindlimb lameness respectively. Changes were documented by changes of the HAAS or the SAAS.In all 4 horses with a true hindlimb lameness a synchronous false lameness of the ipsilateral forelimb was documented. In 6 of 10 horses with a forelimb lameness a lameness transfer could be assessed according to hypothesis 2.The results of this study show, that horses with a true severe lameness in the forelimb show a false lameness in the contralateral hindlimb, and horses with a true hindlimb lameness show a false lameness in the ipsilateral forelimb. This indicates that the location of the truly lame limb can be deduced from the distribution of 2 lamenesses on a sagittal or diagonal axis.
Fetal calcium homeostasis
Authors: CARE A. D. 
Published: June 2010

SummaryThe mammalian fetus is maintained hypercalcaemic relative to its mother primarily by the action of a placental calcium pump located in the basal plasma membrane of the trophoblast. It is suggested that the activity of this pump is stimulated by a mid‐molecular fragment of parathyroid hormone‐related protein [PTHrP(38–94NH2)], produced in the placenta (and also in the parathyroid glands of fetal lambs and calves) as a result of post translational processing. In the sheep, calcitriol is an important determinant of fetal calcium homeostasis and it, too, stimulates the transport of calcium across the placenta. Fetal bone resorption is under the control of calcitriol, parathyroid hormone (PTH) and PTHrP. This resorption is modulated by the inhibitory effect of calcitonin. PTHrP also plays an important role in the regulation of endochondral ossification and chondrocyte maturation.
Immunolocalisation of P450C17 in the fetal sheep adrenal gland during gestation and in response to ACTH and glucocorticoid administration
Authors: HAN X. , BERDUSCO E. T. M. , LU FENG , CHALLIS J. R. G. 
Published: June 2010

SummaryIn sheep, increased output of Cortisol from the fetal adrenal gland is critical to organ maturation and parturition. Cortisol synthesis is determined in part by the activity of P450C17 enzyme. We have used immunohistochemistry and Western immunoblotting to examine the distribution of P450C17 in the ovine fetal adrenal during gestation, and after ACTH or dexamethasone administration to fetuses between Days 125 and 130. The patterns were compared with changes in 3β‐hydroxysteroid dehydrogenase (3β‐HSD) localisation and levels. Adrenal tissue was obtained from four fetuses at each of Days 63–65, 100, 125–130 and term (>140 days). Further animals were chronically catheterised and infused with ACTH, dexamethasone or saline for 96 h beginning on Day 125. Immunohistochemistry for P450C17, 3β‐HSD, and phenylethanolamine‐N‐methyl transferase (PNMT) was conducted using standard techniques. At Day 63–65 of pregnancy immunoreactive (ir‐)P450C17 was present in cords of cells throughout the adrenal gland. Ir‐P450C17 was reduced or was undetectable at Day 100, but had increased by Day 125–130, and was present throughout the zona fasciculata of the adrenal cortex of term animals. An increase in P450C17 protein was also seen between Day 100 and 125 by Western blotting, and after ACTH treatment. Dexamethasone administration led to a marked reduction in ir‐P450C17 levels. In contrast, ir‐3β‐HSD was present in the fetal adrenal cortex between Day 100 and term, and was less affected by ACTH or dexamethasone treatment. We conclude that P450C17 in the fetal sheep adrenal is responsive to regulation by ACTH, and that changes in its levels correlate with previously reported alterations in patterns of Cortisol output by the fetal adrenal gland.
Follicular dynamics in Mangalarga mares
Authors: BURATINI J. , e SILVA A. A. M. ROSA , BARROS C. M. Q. , PAPA F. O. , CALDAS M. C. S. , MEIRA C. 
Published: June 2010

SummaryOvarian follicular activity was studied by ultrasonography during 17 oestrous cycles in 9 Mangalarga mares during the second half of the ovulatory season. Sixteen oestrous cycles were considered normal and one 3‐wave cycle showing a prolonged luteal phase was considered atypical. Daily ultrasonographic examinations were performed and the compiled data on follicular dynamics were studied retrospectively. One major wave of follicular growth was observed in 13 of the 16 normal cycles (81.25%), whereas 2 major waves occurred in 3 cycles (18.75%). The mean (± s.d.) days of emergence of the primary wave of follicular development in cycles containing one or 2 waves were Day 6.0 ± 2.3 and Day 11.0 ± 1.0, respectively. The secondary wave of follicular development in 2‐wave cycles emerged on Day 0.0 ± 3.6. The day of wave divergence for primary waves of follicular development in cycles which exhibited one or 2 major waves were Day 12.2 ± 3.5 and Day 173 ± 3.0, respectively. Divergence of secondary waves occurred in only one of the 3 cycles which exhibited 2 major follicular waves (Day 7). The mean (± s.d.) maximum diameters of the dominant follicle in the primary wave of oestrous cycles exhibiting one and 2 major waves were 39.0 ± 3.9 mm and 34.7 ± 2.5 mm, respectively. The mean (± s.d.) maximum diameter of the dominant follicle present in the secondary wave was 34.3 ± 11.0 mm. The mean (± s.d.) lengths of the interovulatory intervals for cycles containing one and 2 major waves were 19.4 ± 2.2 and 23.3 ± 2.5 days, respectively. These data indicate that most Mangalarga mares show one major follicular wave during the oestrous cycle but a small percentage of mares show 2 major waves.
A comparison of the biochemical composition of equine follicular fluid and serum at four different stages of the follicular cycle
Authors: COLLINS ANNA , PALMER E. , BÉZARD JACQUELINE , BURKE JEAN , DUCHAMP G. , BUCKLEY T. 
Published: June 2010

SummarySamples of blood and follicular fluid were recovered from 27 Welsh Pony mares at 4 distinct stages of follicular development. Eighteen biochemical parameters were measured in each sample, including sodium, potassium, chloride, glucose, urea, creatinine, calcium, inorganic phosphate, total bilirubin, total protein, albumin, magnesium, triglyceride, total cholesterol, nonesterified fatty acids, alkaline phosphatase, γ‐glutamyltransferase and aspartate aminotransferase. The concentrations of progesterone, 17β oestradiol and testosterone, pH and osmolarity, were also measured in all the follicular fluid samples. The concentrations of all proteins measured were lower in follicular fluid than serum whereas the reverse was true in the case of the lipids. Analysis of variance indicated that serum and follicular fluid concentrations of most of the parameters measured varied in parallel.