bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryopreservation of equine embryos using glycerol and 1,2‐propanediol as cryoprotectants
Authors: MEIRA C. , ALVARENGA M. A. , PAPA F. O. , OBA E. , e ALVARENGA F. C. LANDIM
Published: June 2010

Equine embryos recovered at Day 6 or 7 after ovulation were deep‐frozen using glycerol (Groups 1 and 2) or 1,2‐propanediol (Group 3). Blastocysts (Bl) and expanded blastocysts (Exbl) were used in Group 1 and tight morulae (Tm) and early blastocysts (Ebl) in Groups 2 and 3. In Group 4 (control), fresh embryos were used. Post‐thawed embryos and fresh embryos were non‐surgically transferred, independently of the morphological appearance, into recipient mares at Day 6 or 7 of dioestrus. Embryo recovery rate was 55.3% (93/168); the pregnancy rates in Groups 1, 2, 3 and 4 were 0% (0/12), 40% (6/15), 0% (0/15) and 80% (12/15) at 15 days respectively. Embryonic losses were 16.7% (1/6) and 8.3% (1/12) in Groups 2 and 4 at 60 days. These results indicate that glycerol was superior to 1,2‐propanediol as a cryoprotectant and that Bl and Exbl were unsuitable for cryopreservation.
In‐vivo fertilisation and initial embryogenesis in the mare
Authors: GRØNDAHL C. , NIELSEN C. GRØNDAHL , ERIKSEN T. , GREVE T. , HYTTEL P.
Published: June 2010

Eleven mares were induced to ovulate by treatment with 3,000 iu hCG and subsequently inseminated with frozen‐thawed semen. The time of ovulation was determined by transrectal ultrasonography of the ovaries performed every 4 h. At different times after ovulation ova were collected from oviducts removed by surgery through a flank incision under general anaesthesia. The presumed fertilised ova were cultured for 20 min in a medium containing [3H]uridine, fixed, embedded in Epon, semithin‐sectioned and processed for autoradiography. Selected semithin sections were re‐embedded and processed for transmission electron microscopy. Spherical, paternal and maternal pronuclei were observed within 12 h after ovulation, and by 19 h the pronuclei had migrated to close apposition. The 2‐cell stage was seen within 34 h and a major activation of RNA synthesis was detected at 64 h after ovulation in 4 blastomeres of a 6‐cell embryo, suggesting maternal‐embryonic transition apparently occurs at the 4th cell cycle.
Modifications in the technique used to recover equine embryos
Authors: ALVARENGA M. A. , e ALVARENGA F. C. LANDIM , MEIRA C.
Published: June 2010

In Experiment I, phosphate‐buffered saline (PBS) or Ringer‐lactate solution (RL) was used to flush embryos from mares, but there was no difference (P>0.05) in pregnancy rate after transfer of embryos: 8/14 (57%) in PBS and 14/22 in RL. There was also no difference (P>0.05) in pregnancy rates in Experiment II when embryos were flushed with PBS alone (53/117, 45%) or PBS + 1% foetal calf serum (37/70, 53%). In Experiment III, the standard technique for embryo recovery gave 55% (11/20) success compared with 75% (18/24) for a modified method whereby 3 min' contact time was allowed in the uterus for each flush, without massage of the uterus, but this was not statistically significant (P>0.05).
The application of embryo transfer to polo ponies in Argentina
Authors: PASHEN R. L. , LASCOMBES F. A. , DARROW M. D.
Published: June 2010

Since the commercial embryo transfer programme for polo ponies in Argentina was started in 1989, 479 of 727 (66%) embryo recovery attempts yielded one or more embryos. Nonsurgical transfer of 580 embryos to synchronised recipient mares resulted in the establishment of 353 pregnancies (61%).
Osteochondrosis in the tarsocrural joint and osteochondral fragments in the fetlock joints in Standardbred trotters. II. Heritability
Authors: Philipsson J. , Andréasson E. , Sandgren B. , Dalin G. , Carlsten J.
Published: June 2010

The progeny (N=793) of 24 Swedish Standardbred trotter stallions were used for genetic studies on radiographic findings of osteochondrosis (OC) in the tarsocrural (hock) joint and palmar/plantar osteochondral fragments (POF) in the metacarpo‐ and metatarsophalangeal (fetlock) joints.

Twenty stallions were drawn at random from the population of Swedish Standardbred trotter stallions approved for breeding, and 4 stallions were selected for their own OC and POF status. The progeny groups included 28–39 investigated yearlings per stallion. About half of the horses were born in each of the years 1988 and 1989.

Hock joint OC was diagnosed in 71 (10.5%) and fetlock joint POF in 145 (21.5%) offspring of the randomly selected stallions. The incidence of OC and POF varied among the progeny groups between 0–24% and 11–44% respectively (P<0.05). The findings were analysed as all‐or‐none traits and as sire‐offspring regressions. Non‐genetic effects of sex, age at examination and year/month of birth were simultaneously considered with genetic effects of sire. The heritability was estimated to be 0.08–0.09 on the threshold scale for both traits, corresponding to 0.24–0.27 for OC and to 0.17–0.19 for POF on the underlying quantitative scale. Sire‐offspring regressions yielded heritabilities of 0.34 and 0.23 for OC and POF, respectively.

Correlations between OC and POF, as well as between these and measures of body size, were contradictory, probably due to the limited amount of data and the all‐or‐none characters of both OC and POF. However, we conclude that the predisposing factors of OC and POF are inherited independently of each other.
Plantar osteochondral fragments in the metatarsophalangeal joints in Standardbred trotters; result of osteochondrosis or trauma?
Authors: Dalin G. , Sandgren B. , Carlsten J.
Published: June 2010

Hindlimb fetlock joints with plantar osteochondral fragments (POF) were collected from 21 horses (17 Standardbred trotters, 4 Swedish Warmblood riding horses; 8 stallions, 5 geldings, and 8 mares; ages 5 months‐21 years) and from 28 horses with no metatarsophalangeal joint pathology. The morphology of the osteochondral fragments and adjacent tissues was studied by dissection, high‐resolution radiography, and histology. There were 22 joints affected, and 20 out of 25 POF found were located medially. In 3 joints there were fragments both laterally and medially. The fragments were attached to the short sesamoidean ligaments and facing the joint cavity they had a smooth cartilage covered surface which measured between 4 times 2 mm and 12 times 6 mm. A small central trabecular osseous core was seen radiographically in the young horses (<1 year of age), and the proportion of the bony component increased during the first years of life. In 18 out of 25 POF sites, a defect was seen in the adjacent bone of the proximal phalanx. Histology did not show any findings indicative of osteochondrosis.

It is suggested that plantar osteochondral fragments are the result of outwardly rotated hindlimb axes and subsequent point loading in the medial fetlock area. Repeated high tension loads in the short sesamoidean ligaments may cause fragments of tissue with osteogenic properties to come off the proximal phalanx into the ligament, later forming osteochondral fragments.
Histomorphometric assessment of bone biopsies from foals fed diets high in phosphorus and digestible energy
Authors: Savage C. J. , McCarthy R. N. , Jeffcott L. B.
Published: June 2010

Bone turnover was estimated from biopsy cores from the wing of ilium in 24 mixed‐bred foals, aged 4.5–6.5 months and divided into 4 groups. A control group was fed according to NRC recommendations for foals growing at 0.65 kg/day, experimental groups diet for 16–18 weeks with additions of phosphorus (P, 388% of control level), digestible energy (DE, 129% of control level) or crude protein (CP, 126% of control level). Bone biopsies were taken in Week 7/8 and again at the end of the trial.

In the first biopsy no significant differences between dietary groups were found. Cortical bone porosity increased over time (P = 0.001) in foals fed High P (17.09 ± 2.25%vs22.41 ± 2.62%). At the end of the study cortical bone porosity was greater (P = 0.02) in foals fed excess P than in other groups. In High P fed foals the extent of osteoid covered surfaces of cancellous bone decreased over time (P = 0.03), and there was a trend towards increased resorption surfaces in the cancellous bone with a subsequent slight decrease in cancellous bone volume. Cortical bone porosity tended to increase in foals fed High DE (P = 0.07) yet no significant alteration was seen in cancellous bone volume. Joint lesions of dyschondroplasia (DCP) were found atpost mortemin foals fed High DE and High P. However, only minor changes in the measurements of bone remodelling were found by histomorphometric analysis. Changes in foals fed High P were consistent with a mild form of nutritional secondary hyperparathyroidism, although no clinical signs were noted.
Longitudinal development of the kinematics of 4‐, 10‐, 18‐ and 26‐month‐old Dutch Warmblood horses
Authors: BACK W. , BARNEVELD A. , SCHAMHARDT H. C. , BRUIN G. , HARTMAN W.
Published: June 2010

The forelimb kinematics of 24 Dutch Warmbloods were recorded at the trot on a treadmill (4m/s) at the age of 4, 10, 18 and 26 months using a modified CODA‐3 apparatus to study the development of the equine locomotor apparatus. Stride and stance duration increased with age, but swing duration and pro‐/retraction angle were consistent. The timing of maximal fetlock extension during the stance phase and carpal flexion during the swing phase did not change significantly as horses grew older. Moreover, individual angle‐time and angle‐angle diagrams recorded at 4 and 26 months showed a remarkable resemblance, both visually and numerically. From these data it can be concluded that horses seem to have an inherent intralimb coordination pattern.
Comparison of the collected, working, medium and extended canters
Authors: CLAYTON HILARY M.
Published: June 2010

High speed cinematography (150 Hz) was used to determine the linear and temporal characteristics of the collected, working, medium and extended canters in 6 highly trained dressage horses. Analysis of variance and Waller‐Duncan Bayes K‐ratio t‐tests were applied to determine which of the measured variables changed significantly among the 4 gait types. The mean speed increased progressively from the collected to working to medium to extended canters (p<0.01). Changes in speed were due to adjustments in stride length while stride duration remained constant. An increase in stride length was the result of increases in the distances between successive limb placements except the diagonal distance between the leading hind and trailing front limbs which did not change. The greatest increase was between the leading front limb and the subsequent placement of the trailing hind limb. Although the same stride duration was maintained in the 4 canter types, there were significant changes in the temporal relationships between the footfalls. The step duration between the 2 front limbs was significantly reduced from the collected to working to medium to extended canters (p<0.01). The step duration between the 2 hind limbs was significantly shorter in the extended than the collected canter (p<0.01). The stride duration was maintained by increasing the duration between the leading front and trailing hind limbs.
The use of a panning camera technique in equine kinematic analysis
Authors: DREVEMO S. , JOHNSTON C.
Published: June 2010

A method applicable for field studies of equine locomotion based on recordings by high‐speed cinematography/videography with a panning camera is presented. A ground reference plane/line was defined by a number of ground reference plates at equidistant intervals along the filming range. One ground reference plate in the middle of the range was predefined and designated as Ref0. The camera position was determined in such a way that the camera axis was perpendicular to the reference line when aiming towards Ref0. The maximum error introduced by the experimental setup was less than 3% and the perspective errors at the end of the recording range less than 0.02 m in a single position determination. The method was applied to study some basic temporal and linear variables and the pastern, metacarpal segment and fetlock joint angles in 6 young Standardbred trotters at 10.2 ± 0.17 m/s. The mean stride and stance durations for the group of horses were 503 ± 15 ms and 131 ± 6 ms, respectively. Indications of laterality in individual horses were observed when diagonal and contralateral pairs of limbs were studied. Sudden angle changes were observed in the fetlock segment and fetlock joint at full support following braking of the fore‐aft horizontal hoof movement.
Analysis of equine gait using three‐dimensional accelerometers fixed on the saddle
Authors: GALLOUX P. , RICHARD N. , DRONKA T. , LEARD M. , PERROT A. , JOUFFROY J. L. , CHOLET A.
Published: June 2010

The aim of this study was to give riding teachers, physiotherapists and research workers a better understanding of the three‐dimensional movement of the horse's saddle. The gaits of 7 horses were recorded on the treadmill by an accelerometric crown fixed to the front of a saddle. After a Fourier analysis of the signal, noise was eliminated; after a double integration data were obtained describing the crown's movement, assuming that after each stride the saddle returns to the original place. The movement was visualised in two and three dimensions. The walk showed more twisting motions, whereas the trot had more rolling, longitudinal and lateral movement. The canter showed the highest amplitude of motion, with a strong pitching rotation but little twisting. The pitching movement was the most important type of rotation for the three gaits. The speed at the canter did not influence the shape of the movement patterns.
Shortening of the hind limb in the horse during the stance phase
Authors: HJERTÉN G. , DREVEMO S. , ERIKSSON L.‐E.
Published: June 2010

Compressions of the hind limb in a horse trotting at 3.7 m/s were studied by use of high‐speed cinematography. It is concluded that distal loading, beginning at the hoof, resulted in a longer impact time and smaller impact forces compared to a theoretical stiff limb. Shortening of the hind limb during the stance occurs from hoof to stifle, while there is an elongation of the distance between the stifle and tuber coxae.
Kinematics of the hind limb push‐off in elite show jumping horses
Authors: VAN DEN BOGERT A. J. , JANSEN MARGOT O. , DEUEL NANCY R.
Published: June 2010

The sagittal plane kinematics of trunk, neck, and hind limb were analysed in a group of 15 elite show jumping horses during the push‐off of the hind limbs before jumping a 1.50 m upright fence. Similar movement patterns were observed in all horses. Ensemble averages of the kinematic variables of the group were calculated after spline smoothing and time‐normalisation with respect to the support phase. The final support phase of the hind limbs was symmetrical and had a duration of 221 ± 19 ms. During the first half of this period, the trunk rotated towards a more upright orientation and the height of the estimated centre of mass was decreased by about 0.05 m. These movements were accompanied by 25 degrees of hip extension and 40 degrees of flexion in the stifle and hock joints. These movements bring the hind limbs into a favourable, flexed position to produce mechanical power and transfer it to the trunk. Maximal flexion in the tarsal joint was reached at 98 ms after ground contact, followed by the stifle joint at 124 ms. After maximal flexion, the total extension movement of the tarsal and stifle joints was 45 and 22 degrees respectively. The extension of the hip continued until 152 ms after ground contact, and the angle remained stationary afterwards. The extension of the hind limb was accompanied by a large increase in horizontal and vertical velocity of the trunk, and a reversal of the rotation of the trunk. The average rate of mechanical power production during the entire push‐off, estimated from the change in kinetic and potential energy, was 59,000 W. By comparing total energy at the beginning and end of the support phase, it was concluded that most of the energy required to clear the fence was produced by the hind limbs during the final support phase, and that the previous actions of the forelimbs are merely bringing the horse into a good position for the final push‐off.
Pulsed wave Doppler echocardiography in normal horses
Authors: BLISSITT KAREN J. , BONAGURA J. D.
Published: June 2010

Reference values were established for selected Doppler derived variables from a group of 40 normal Thoroughbred and Thoroughbred cross horses. Standard two‐dimensional (2‐D) images used for guiding the Doppler sampling site allowed accurate alignment with flow. Tricuspid inflow velocities during rapid filling (E) and atrial contraction (A) were significantly higher when recorded from a right parasternal angled view than from a right parasternal long‐axis view. In 8 horses the tricuspid inflow peak A velocity was higher than the peak E velocity. The peak acceleration of blood flow was higher (P=0.000) in the aorta (mean 8.01 m/s/s) than in the pulmonary artery (4.45 m/s/s). Significant differences were also noted in the pre‐ejection period, ejection time and acceleration time between the 2 vessels. Horses with functional ejection murmurs had lower peak aortic acceleration and a longer acceleration time than horses without flow murmurs. Horses with filling murmurs over the left hemithorax had a significantly higher peak mitral E velocity than horses without such murmurs. Measurements from Doppler waveforms were repeatable and may prove useful in assessing ventricular function in this species.
Physiological valvular regurgitation in clinically normal young racehorses: prevalence and two‐dimensional colour flow Doppler echocardiographic characteristics
Authors: MARR CELIA M. , REEF VIRGINIA B.
Published: June 2010

Colour flow Doppler echocardiographic examinations were performed on 15 horses; 10 Thoroughbreds and 5 Standardbreds; 9 mares, 5 geldings and 1 stallion; mean ± s.d. 3.4 ± 1.1 years. Cardiac murmurs were audible in 12 horses (80%), but these had characteristics consistent with functional murmurs in all horses. A standardised two‐dimensional (2‐D) and M‐mode echocardiographic examination was unremarkable in all horses except that aortic valve prolapse was identified in 3 horses, tricuspid valve prolapse in 2 horses and mitral valve prolapse was present in one horse. Colour flow Doppler echocardiography revealed laminar antegrade flow in most sites but variance was noted in the right ventricular outflow tract in some horses. Small regurgitant jets associated with the aortic valve were seen in 12 horses (80%), with the tricuspid valve in 7 horses (46%), with the pulmonary valve in 4 horses (26%) and the mitral valve in 4 horses (26%). It was concluded that with colour flow Doppler echocardiography, as in other species, small regurgitant jets could be detected in many normal horses.
The haemodynamic effects of milrinone HCl in halothane anaesthetised horses
Authors: MUIR W. W.
Published: June 2010

The haemodynamic effects of milrinone hydrochloride were determined in halothane‐anaesthetised horses. Six healthy adult horses were anaesthetised with guaifenesin and thiamylal and maintained with halothane in oxygen (end‐tidal halothane concentration of 1.15%). Baseline haemodynamic data were recorded after a 45 min stabilisation period. All 6 horses received a single loading dose of milrinone HCl, 0.2 μg/kg i.v., followed by progressively increasing infusions of 2.5, 5, 10 and 20 μg/kg bwt/min. Each infusion lasted for 15 min and produced dose related increases in heart rate, mean arterial blood pressure, cardiac output, maximum rate of increase and decrease of left ventricular pressure (± dP/dtmax) and ejection fraction in halothane anesthetised horses. Median artery blood flow increased following milrinone administration. Right atrial and pulmonary artery pressures, systemic vascular resistance and left ventricular end‐diastolic and end‐systolic volumes decreased. Most haemodynamic changes were sustained throughout the infusion period and for 30 min following the termination of milrinone infusion. Systemic vascular resistance was increased above baseline values at 30 min following the termination of milrinone infusion. No adverse side effects were observed during this study although a milrinone infusion rate of 20 μg/kg bwt/min increased heart rate to values greater than 50 beats/min. The results of this study suggest that milrinone produces beneficial haemodynamic effects in halothane anaesthetised horses and is potentially useful in the treatment of patients with a reduced cardiac output.
Plasma volume and ions during exercise in cool, dry; hot, dry; and hot, humid conditions
Authors: LINDINGER M. I. , GEOR R. J. , ECKER GAYLE L. , McCUTCHEON L. J.
Published: June 2010

We studied the effects of heat and relative humidity (RH) on plasma volume (PV) and ion responses to submaximal exercise and 60 min recovery in Thoroughbreds. Five horses were exercised at 50% of peak V̇O2in cool, dry (CD, T=22°C, RH=45–55%), and hot, humid (HH, T=30–34°C, RH=80–85%) conditions until a pulmonary artery temperature of 41.5°C was reached. Blood was obtained from the carotid artery. Body mass was measured at rest and after 30 min of recovery. The thermal conditions had no effect on the PV and ion responses during exercise and initial 30 min of recovery. Exercise resulted in an 8.5% decrease in PV within the first 2 min and, in the absence of changes in plasma [Na+] and [Cl−], was responsible for a 150 to 185 mmol decrease in plasma Na+and Cl−contents. The decrease in PV was responsible for about 50% of the increase in packed cell volume (37% at rest; 51% at 2 min of exercise).

Plasma [K+] and K+content increased rapidly during the first 2 min of exercise. With cessation of exercise, plasma [K+] declined with a half time of about 2 min; recovery of PV and plasma Na+and Cl−contents occurred with a half time of 10–15 min, with nearly complete recovery by 30 min. In the HD trial, between 30 and 60 min of recovery there were further decreases in PV and ion contents. It is concluded that with this exercise protocol, thermal stress had minimal influence on the rate and magnitude of exercise‐induced changes in PV and ion contents. However, thermal stress during recovery from exercise may impede the restoration of PV and ion contents.
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

In 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

Significant 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

A 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

Heart 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

Nine 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

The 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

The 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

The 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

In 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.
Embryological development of the equine heart
Authors: COTTRILL CAROL M. , HO S. YEN , O'CONNOR W. N.
Published: June 2010

‘;There go stoutness, strength, and speed … and great hearts to face their fate …’ from The Remount Train by W.H. Ogilvie
Fetal calcium homeostasis
Authors: CARE A. D.
Published: June 2010

The 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

In 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

Ovarian 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

Samples 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.
Transfer of immature oocytes to a preovulatory follicle: An alternative to in vitro maturation in the mare?
Authors: GOUDET GHYLÈNE , BÉZARD JACQUELINE , DUCHAMP G. , PALMER E.
Published: June 2010

In the mare, success rates for the in vitro maturation of oocytes are low. Accordingly, we attempted to determine if immature oocytes could be matured in vivo by injecting them into a preovulatory follicle. Groups of 3–9 oocytes collected from donor mares were transferred under ultrasound control into the preovulatory follicle of a recipient mare that was treated with crude equine pituitary gonadotrophin (CEG) to induce ovulation. Just before ovulation (34 h post treatment) the preovulatory follicle of the recipient mare was punctured to collect both the transferred and the indigenous oocytes to analyse the stages of nuclear maturation.

The transfer technique did not impair significantly the final maturation of the recipient preovulatory follicle. The indigenous oocytes within the recipient follicles were recognisable by their larger expanded cumulus of yellow colouration due to high hyaluronic acid content; 7/12 of these oocytes were mature (metaphase II). Around half (42/86; 49%) of the oocytes transferred to preovulatory follicles were recovered subsequently. Most of them showed cumulus expansion (41/42, 6 of which were rich in hyaluronic acid), 13 (32%) were mature, 15 (36%) were immature and 13 (32%) were degenerate. When the indigenous oocyte of the recipient mare was mature, 38% of the transferred oocytes were mature, this rate being no different from the in vitro maturation rate of 46%.

This study showed that in vivo maturation of immature oocytes by transfer into a preovulatory follicle in a recipient mare is possible. The maturation rate is not different from the in vitro maturation rate. The technique allows the generation of mature oocytes that have an expanded cumulus rich in hyaluronic acid, similar to the situation in preovulatory oocytes. This result has not been obtained in vitro previously.