bluuebunny/crossref_metadata_2025 huggingface dataset:
Modified ventilated capsule for the measurement of sweating rate in the exercising horse
Authors: SCOTT C. M. , MARLIN D. J. , SCHROTER R. C.
Published: June 2010

Modification of a ventilated capsule technique for the measurement of sweating rate (SR) is described for application in an exercising horse. The plastic capsule was sealed against the coat of the horse. Dry air was blown through the capsule over the skin and the change in absolute humidity (g/m3) between air entering and leaving the capsule was used to calculate SR. The effect of flow rate on the response characteristics of the system was investigated and measured over a range of sweating rates in a group of horses completing a short exercise test. Repeatability of SR measurements made at 2 sites, one 10 cm distal to thetuber sacrale(SRS) and the other approximately overlying C4 in the neck (SRN), were compared.

To encourage the rapid and complete evaporation of moisture from the area of coat enclosed by the SR capsule, it was demonstrated that the degree of saturation of the air leaving the capsule should be maintained below 15% relative humidity (RH). This was best achieved at flow rates exceeding 35 l/min. No significant difference was found between the 2 repeated tests separated by 3 days, with respect to right atrial temperature (TRA) and SR. The modified system for the measurement of SR in the exercising horse used in this study was shown to be fast responding and capable of measuring a wide range of sweating rates. A good seal was maintained throughout and the capsule was removed without causing damage to the coat.
Sweat fluid and ion losses in horses during training and competition in cool vs. hot ambient conditions: implications for ion supplementation
Authors: McCUTCHEON L. J. , GEOR R. J.
Published: June 2010

The objectives of this study were to: 1) determine incremental and total sweat fluid and ion losses during and following (a) exercise training and (b) a treadmill Speed and Endurance exercise test (SEET) which simulated running speeds and distances required for each phase of an Olympic level (CCI****) 3‐day‐event in cool and hot ambient conditions and 2) determine the requirement for ion supplementation based on the calculated ion losses associated with these activities. Six exercise‐trained Thoroughbred horses completed 2 weeks of exercise training in each of 2 ambient conditions: cool, dry (CD, room temperature [T] = 20–22°C, relative humidity [RH] = 45–55%), or hot and humid (HH, T = 33–35°C, RH = 80–85%). Following the 2 week period of training in either CD or HH conditions, horses completed a SEET under similar conditions (either CD, or hot and dry (HD, T = 33–35°C, RH = 45–55%). Sweating rate and sweat ion composition for each 5 min interval was determined from sweat samples collected from a sealed pouch attached to the lateral thorax. Total sweat fluid losses during training in the heat were 2‐ or 3‐fold greater when compared to CD. Similarly, sweat fluid losses associated with the SEET in HD were almost double (19.2 litres) the losses in CD (11.7 litres). Total calculated ion losses associated with 2 h of training in HH (3724 mmol; 115.2 g) were significantly greater when compared to CD (1413 mmol; 43.5 g). Following the SEET and a 30 min recovery period, total ion losses in CD were 3636 mmol (112.2 g) compared with 6519 mmol (200.6 g) in HD. The differences in ion losses represent the increased sweating rates stimulated by higher core temperatures during moderate to high intensity exercise in warmer ambient conditions and increases in sweat ion concentrations associated with higher sweating rates. Extracellular fluid (ECF) ion losses during daily exercise training and the SEET were also calculated from changes in plasma ion concentrations and ECF volume. Calculated ECF ion losses were significantly higher in hot ambient conditions but were approximately 50% less than calculated sweat ion losses. The calculated sweat ion losses incurred during daily exercise training in hot and humid ambient conditions are >3‐fold higher than losses measured following exercise training in cooler conditions. Whereas fluid regulating hormones may have reduced urinary and faecal losses of ions during 2 weeks of training in HH, the quantity of sodium, potassium and chloride calculated to have been lost in sweat during the SEET in HD exceeded the daily dietary intake of these ions and suggests the need for appropriate ion supplementation during training and competition in hot ambient conditions.
Adaptations to daily exercise in hot and humid ambient conditions in trained Thoroughbred horses
Authors: GEOR R. J. , McCUTCHEON L. J. , LINDINGER M. I.
Published: June 2010

The objectives of this study were to: 1) determine the effects of heat and high relative humidity (RH) on the clinical and physiological responses of horses during and after daily exercise training and 2) determine whether repeated exposure to, and exercise in, the heat would result in improved thermal tolerance (heat acclimation). Six trained Thoroughbred horses completed 1 h of submaximal exercise in cool, dry conditions (CD) and during a daily 4 h period of exposure to high heat and humidity (HH, room temperature = 33–35°C, RH = 80–85%) for 22 days. Rectal temperature (Tre) and heart rate (HR) were measured before, during and after exercise and respiratory rate (RR) was measured before exercise and during a 2 h recovery. In HH, the rate of rise in Trewas significantly higher than in CD. However, by HH Day 5, Trebefore, during and after exercise was significantly lower than on HH Day 1. The day‐to‐day decrease in Treduring exercise was reflected in significant decreases in heat storage following exercise by HH Day 10 (910 ± 47 kcal) when compared to HH Day 1 (1211 ± 75 kcal). At rest, RR was initially higher in HH than CD, and a further increase in pre‐exercise RR from HH Day 1 to Day 10 may have contributed to the lower pre‐exercise Tre. Recovery RR was higher after HH Day 1 and was associated with a lower end‐of‐exercise Treand reduced heat storage by HH Day 5. Pre‐exercise HR did not change in the 1 h before exercise in CD and did not differ from HH Days 1–22. By HH Day 10, mean HR during the latter part of exercise was lower than HH Day 1 and was not different from pre‐exercise by 60 min of recovery. Pre‐exercise body mass did not change during the 3 wk period, and the decrease in body mass that occurred during the 4 h training period was significantly attenuated by HH Day 15 (9.8 ± 0.8 kg) when compared to HH Day 1 (12.5 ± 0.8 kg). Over the 3 week period of HH, mean 24 h water consumption increased from 26.0 ± 2.1 litres to 39.5 ± 3.2 litres, largely reflecting a 2‐fold increase in water intake during the 4 h period of heat exposure. It is concluded that 3 weeks of daily exposure to, and exercise in, hot and humid ambient conditions resulted in a progressive reduction in thermal and cardiovascular strain. Furthermore, the reported physiological adaptations are consistent with an improved thermal tolerance (heat acclimation).
Physiological responses in nonheat acclimated horses performing treadmill exercise in cool (20°C/40%RH), hot dry (30°C/40%RH) and hot humid (30°C/80%RH) conditions
Authors: MARLIN D. J. , SCOTT C. M. , SCHROTER R. C. , MILLS P. C. , HARRIS R. C. , HARRIS PATRICIA A. , ORME C. E. , ROBERTS C. A. , MARR CELIA M. , DYSON SUE J. , BARRELET F.
Published: June 2010

The aim of the present study was to determine the effect of different environmental conditions on physiological response to exercise. Four winter acclimatised, nonheat acclimated horses of different breeds were exercised at 20°C/40%RH (CD), 30°C/40%RH (HD) and 30°C/80%RH (HH). The exercise test was designed to represent the structure and intensity of a One star Speed and Endurance test (competition exercise test [CET]). All 4 horses were able to complete the full CET (60 min + 30 min active recovery) in CD and HD, but only one horse completed the CET in HH. Two horses were stopped because of pronounced general fatigue and one because of a right atrial temperature (TRA) of 43°C. Oxygen uptake on each phase was not different between CD and HD, but was higher duringPhases B, CandDin HH. Mean peak TRAat the end ofPhase Dwas 40.3 ± 0.2, 41.6 ± 0.4 and 42 ± 0.3°C for CD, HD and HH, respectively. Corresponding, mean peak rectal temperatures (TREC) followingPhase Dwere 39.5 ± 0.1, 40.6 ± 0.1 and 41.5 ± 0.1°C for CD, HD and HH, respectively. Mean time to peak TRECwas 9.3 ± 1.1 (CD), 7.3 ± 1.8 (HD) and 10.8 ± 2.3 (HH) min and was not significantly different between conditions (P>0.05). Heat dissipation amounted to 83 ± 1, 73 ± 2 and 70 ± 1% of heat production in CD, HD and HH, respectively. Weight loss was significantly correlated with both body surface area (CD r = 0.85; HD r = 0.87; HH r = 0.81) and bodyweight (CD r = 0.97; HD r = 0.93; HH r = 0.94). The greatest weight loss recorded was 4.6% bodyweight in one horse in HD. The mean increase in exercise intensity over the whole CET (in terms of V̇O2) of HD and HH compared with CD was 5 ± 3 and 14 ± 3% higher, respectively. The exercise induced hyperthermia and the reduced capacity for heat dissipation produced partial compensatory responses in minute ventilation (V̇E), particularly duringPhase C, when the horses were trotting. In HD, the increase in V̇Ewas achieved mainly through an increase in frequency, whilst in HH it was achieved through an increase in tidal volume (VT). The horses demonstrated a high degree of tolerance to environmental heat load, suggesting a high thermoregulatory capacity. However, for unacclimatised animals exercising in severely hot and humid conditions, performance may be limited.
Biochemical changes in Three‐day‐event horses at the beginning, middle and end ofPhase Cand afterPhase D
Authors: WILLIAMSON LISA H. , ANDREWS F. M. , MAYKUTH PATRICIA L. , WHITE SUSAN L. , GREEN ELEANOR M.
Published: June 2010

Blood samples were collected 12–16 h before the Speed and Endurance test, immediately after steeplechase, midway throughPhase C(4 km marker), at the end ofPhase Cand immediately after cross‐country from 36 horses that completed a 3‐day‐event at the CCI* (n = 19) or CCI**(n = 17) level. Packed cell volume (PCV), plasma concentrations of sodium, potassium, chloride, ionized calcium, pH and lactate; and serum concentrations of total protein (TP), albumin, total calcium, alkaline phosphatase (AP), gamma glutamyl transferase (GGT), creatine kinase (CK), aspartate aminotransferase (AST), glucose and creatinine were measured. No differences were noted in any biochemical measurements between the CCI* and CCI** horses at any sampling time, despite differences in speed and length of various phases of the Speed and Endurance test. For all horses (n = 36), biochemical parameters changed significantly over time (P<0.01). The PCV, calcium, potassium, lactate, total protein and albumin concentrations were significantly increased over pre‐exercise concentrations immediately afterPhase B.DuringPhase C, these parameters decreased towards pre‐exercise concentrations, thereby supporting the concept thatPhase Cis a recovery phase. In contrast, chloride concentration decreased, and the creatinine concentration and CK increased compared to pre‐exercise concentrations from the end ofPhase Bto the end ofPhase C.These changes probably resulted from fluid and electrolyte losses in sweat, reduced renal blood flow and continued muscular activity. Many parameters did not change significantly between the 4 km marker (midway point onPhase C) and the end ofPhase C.However, there were a few notable exceptions: potassium, chloride, lactate and glucose concentrations decreased, whereas pH and creatinine concentrations increased significantly from the 4 km marker to the end ofPhase C.The most significant benefit of the extra distance from the 4 km marker to the end ofPhase Cwas that it facilitated further dissipation of lactate concentrations prior to the start ofPhase D.
Strategies for voluntary rehydration in horses during endurance exercise
Authors: NYMAN S. , JANSSON A. , DAHLBORN K. , LINDHOLM A.
Published: June 2010

To avoid dehydration and a decrease in performance capacity in horses, fluid and electrolyte losses need to be compensated for during long distance rides as well as on other occasions when sweat losses are high during exercise. Thirteen endurance‐trained horses, age 5–14 years, were used to compare 3 strategies of voluntary rehydration during prolonged exercise, offering 1)water, 2) water after administeringsalt paste(3 times 30 g of NaCl)per osand 3) 0.9% saline. The ride covered 62 km and consisted of 3 rounds, of 20, 22 and 20 km, respectively. During the first 20 km, no fluid was offered to any of the horses. Thereafter, fluid was repeatedly offered from buckets at the ‘vet gates' and at fluid stations situated in the middle of the rounds. Fluid intake and bodyweight were measured during the ride and up until 3 h after the ride. The low heart rates and unchanged plasma glucose concentration indicated that the work load was moderate. Total fluid intake was significantly higher in thesalinegroup than in thewatergroup or thesalt pastegroup. The total plasma protein concentration (TPP) fell below resting values in thesalinegroup post exercise, indicating an increase in plasma volume. No changes in TPP were seen in the other groups. Plasma sodium concentration during the ride increased in thesalt pastegroup but not in thesalinedrinking horses despite their higher NaCl intake. Thewatergroup had an increased plasma aldosterone concentration post exercise, indicating that sodium‐conserving mechanisms had been activated. Plasma potassium concentration decreased in all treatments from pre‐ to post ride. It was concluded, that drinking saline solution during and after exercise is a good strategy for rehydration since this group showed the fastest recovery of their bodyweight losses. The persistently elevated plasma sodium concentration in thesalt pastegroup during the ride, is indicative of a disturbance in the fluid distribution between the body fluid compartments, which can be exacerbated by the low water intake. To give salt paste immediately before or during exercise is, therefore, not recommended.
Impact during equine locomotion: techniques for measurement and analysis
Authors: BURN J. F. , WILSON A. , NASON G. P.
Published: June 2010

Impact is implicated in the development of several types of musculoskeletal injury in the horse. Characterisation of impact experienced during strenuous exercise is an important first step towards understanding the mechanism for injury. Measurement and analysis of large, short duration impacts is difficult. The measurement system must be able to record transient peaks and high frequencies accurately. The analysis technique must be able to characterise the impact signal in time and frequency. This paper presents a measurement system and analysis technique for the characterisation of large impacts.

A piezo‐electric accelerometer was securely mounted on the dorsal surface of the horses hoof. Saddle mounted charge amplifiers and a 20 m coaxial cable transferred these data to a PC based logging system. Data were down‐loaded onto a UNIX workstation and analysed using a proprietary statistics package.

The values of parameters calculated from the time series data were comparable to those of other authors. A wavelet decomposition showed that the frequency profile of the signal changed with time. While most spectral energy was seen at impact, a significant amount of energy was contained in the signal immediately following impact. Over 99% of this energy was contained in frequencies less than 1250 Hz.

The sampling rate and the frequency response of a measurement system for recording impact should be chosen carefully to prevent loss or corruption of data. Time scale analysis using a wavelet decomposition is a powerful technique which can be used to characterise impact data. The use of contour plots provides a highly visual representation of the time and frequency localisation of power during impact.
Noninvasive photoelastic method to show distribution of strain in the hoof wall of a living horse
Authors: DAVIES H. M. S.
Published: June 2010

A photoelastic method used for materials testing in industry was adapted to show the distribution of strain through the hoof wall in the living horse. Strain was a change in length per unit length in the material of the loaded hoof wall compared with the unloaded condition. Coloured fringes appeared in the photoelastic plastic where there were differences in strain between adjacent sites (strain gradients) in the hoof. Strain distribution was observed in the shod and unshod hoof wall of the front hooves of 6 sound horses with hooves that appeared ‘good’ to visual inspection, and one unsound horse with hoof cracks. No significant differences in strains were apparent across the hoof walls of the sound horses when the horses were standing normally. Steep strain gradients were apparent in hooves, associated with defects such as cracks, unstable nail holes, and long toes.
Image analysis to measure activity index of animals
Authors: BLOEMEN HEIDI , AERTS JEAN‐MARIE , BERCKMANS D. , GOEDSEELS V.
Published: June 2010

The objective of the study was to present a method to quantify the behavioural response of animals to their micro‐environment by using a camera system and a digitiser board. An algorithm was developed for analysing images and calculating activity, occupied zone and boundary of the animals. The developed method was tested on 3 different applications and animals. In the first application, the behavioural responses of broiler chickens to their thermal environment was measured. In the second application behavioural responses of pigs to their thermal environment were measured. In the third application, the response of water fleas to a chromium pollution was measured using the developed technique.

Based on the experimental results, it can be concluded that the developed image analysis technique can be employed to quantify the behavioural responses of the tested animals to their micro environment, in an easy and accurate way.
Mechanical properties of pathological equine superficial digital flexor tendons
Authors: CREVIER‐DENOIX NATHALIE , COLLOBERT CLAIRE , POURCELOT P. , DENOIX J.M. , SANAA M. , GEIGER D. , BERNARD NADINE , RIBOT X. , BORTOLUSSI C. , BOUSSEAU B.
Published: June 2010

The objective of this study was to mechanically characterise superficial digital flexor tendon (SDFT) lesions. Eight pathological SDFTs, isolated from 6 adult horses, were tested in traction until rupture (at 1 mm/s). The stresses and strains simultaneously undergone by each of the 7 segments of a tendon were determined throughout the test, and the modulus of elasticity of each segment was evaluated from the segmental stress‐strain curve thus obtained. These mechanical data were compared to those obtained on 10 normal SDFTs. After the test, the tendinous segments were submitted to a histological examination in order to characterise the tissues. Three lesionalcategories(ItoIII, of increasing maturity), as well as the normal tendinous tissue, were defined and assessed quantitatively according to their extent in the histological sections.

The most recent and severe lesions (categories IandII) were correlated with a large degree of hypertrophy (often above 200%) of the corresponding segments, with a resulting decrease in the stress at tendon rupture, and a slight decrease in the strain at tendon rupture in spite of a low modulus of elasticity (low stiffness). In contrast, the adjacent areas, less or not injured, underwent compensatory strains. This relative overstraining was especially critical withcategory IIItissue, often present in the transitional areas between sound and severely injured segments. Here the modulus of elasticity was low whereas the hypertrophy was only slight. Therefore, the corresponding segments seemed to be the most fragile sites, and those most predisposed to recurring injury, in an injured SDFT.
Components of the total kinetic moment in jumping horses
Authors: GALLOUX P. , BARREY E.
Published: June 2010

Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 times 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take‐off, jump and landing phases. It was found that the trunk, hindlimbs and head‐neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 ± 5°/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 ± 125 kg.m2/s).
Analysis of the equine jumping technique by accelerometry
Authors: BARREY E. , GALLOUX P.
Published: June 2010

The purpose of this study was to demonstrate the relationships between jumping technique and dorsoventral acceleration measured at the sternum. Eight saddle horses of various jumping abilities competed on a selective experimental show jumping course including 14 obstacles. An accelerometric belt fastened onto the thorax continuously measured the dorsoventral acceleration during the course. At each jump, 11 locomotor parameters (acceleration peaks, durations and stride frequency) were obtained from the dorsoventral acceleration‐time curves. The type of obstacle significantly influenced the hindlimb acceleration peak at take‐off and the landing acceleration peak (P<0.01). The poor jumpers exhibited a higher mean forelimb acceleration peak at takeoff, a higher forelimb/hindlimb ratio between peaks of acceleration (F/H), and a lower approach stride frequency than good jumpers. Knocking over an obstacle was significantly associated with a low hindlimb acceleration peak at take‐off and a high F/H ratio (P<0.01). In order to observe the continuous changes in the frequency domain of the dorsoventral acceleration during the approach and take‐off phase, a Morlet's wavelet analysis was computed for each horse jumping over a series of 3 vertical obstacles. Different patterns of time‐frequency images obtained by wavelet analysis were found when the horse either knocked over a vertical obstacle or cleared it. In the latter case, the image pattern showed an instantaneous increase in stride frequency at the end of the approach phase, and a marked energy content in the middle frequency range at take‐off.
Classification of collected trot, passage and piaffe based on temporal variables
Authors: CLAYTON HILARY M.
Published: June 2010

The objective was to determine whether collected trot, passage and piaffe could be distinguished as separate gaits on the basis of temporal variables. Sagittal plane, 60 Hz videotapes of 10 finalists in the dressage competitions at the 1992 Olympic Games were analysed to measure the temporal variables in absolute terms and as percentages of stride duration. Classification was based on analysis of variance, a graphical method and discriminant analysis. Stride duration was sufficient to distinguish collected trot from passage and piaffe in all horses. The analysis of variance showed that the mean values of most variables differed significantly between passage and piaffe. When hindlimb stance percentage was plotted against diagonal advanced placement percentage, some overlap was found between all 3 movements indicating that individual horses could not be classified reliably in this manner. Using hindlimb stance percentage and diagonal advanced placement percentage as input in a discriminant analysis, 80% of the cases were classified correctly, but at least one horse was misclassified in each movement When the absolute, rather than percentage, values of the 2 variables were used as input in the discriminant analysis, 90% of the cases were correctly classified and the only misclassifications were between passage and piaffe. However, the 2 horses in which piaffe was misclassified as passage were the gold and silver medallists. In general, higher placed horses tended toward longer diagonal advanced placements, especially in collected trot and passage, and shorter hindlimb stance percentages in passage and piaffe.
Comparison of the temporal kinematics of the canter pirouette and collected canter
Authors: BURNS THERESA E. , CLAYTON HILARY M.
Published: June 2010

The objectives were to compare the temporal characteristics of canter pirouette strides with collected canter strides in elite dressage horses, and to determine whether the stride kinematics of the canter pirouettes fulfilled the requirements specified in the Fédération Equestre Internationale Rules for Dressage Events. Eleven horses were videotaped (60 fields/s) during the individual medal competition at the 1992 Olympic Games. Temporal variables were extracted from the videotapes using standard methods. Two strides were analysed on each of the left and right leads and these were pooled to give mean values for the collected canter and the pirouettes. The pirouettes were completed in 4–9 strides, (mean of 6.4). In the collected canter strides, mean duration of the suspension was 0.013s. There was no suspension in any of the pirouette strides, instead the stance phases of the leading forelimb and trailing hindlimb overlapped by a mean of 0.163s. In 9 horses the trailing forelimb contacted the ground before the diagonal leading hindlimb in the collected canter, whereas in the pirouettes the leading hindlimb always made contact before the trailing forelimb (mean dissociation 0.164s), giving the strides a distinct 4 beat rhythm. Due to increases in advanced placement between the diagonal limb pair and between the 2 forelimbs, the stride duration was longer in the pirouette (0.879s) than the collected canter (0.629s). It is concluded that the canter pirouette strides did not maintain the rhythm and timing of the the collected canter strides in any of the 11 horses.
Aspects of postural development in the rat
Authors: GRAMSBERGEN A. , VAN DER AA M. , GEISLER H. C.
Published: June 2010

The activation patterns in the longissimus and gastrocnemius muscles during the development of the mature type of locomotion were studied in rats from the 11th day until maturity. The EMG's of these muscles were recorded and movements were simultaneously recorded on videotape. Results indicate that during locomotion at early ages, the longissimus muscles are activated irregularly. From the 16th day, the bursts in the longissimus muscle become more pronounced. During locomotion, they are activated differentially and often a simultaneous activation of the longissimus and the contralateral gastrocnemius muscle was observed. From the 20th day, bursts in the gastrocnemius muscle during walking coincide with bursts in the ipsilateral longissimus muscle. Our results demonstrate that the mature type of postural control (from the 20th day) develops a few days after the development of the mature type of fluent walking (around the 15th‐16th day).
Comparison of stride characteristics in a cantering horse on a flat and inclined treadmill
Authors: KAI M. , HIRAGA A. , KUBO K. , TOKURIKI M.
Published: June 2010

The purpose of this study was to determine whether there was any difference in the stride characteristics between cantering on a flat or inclined treadmill. Five 2‐year‐old Thoroughbred horses were cantered on a treadmill at 3 different velocities and at 3 different slopes. The sequence of speeds at each slope was chosen at random and 16 mm cine‐films at 300 frames/s were taken from a lateral view at a distance of 15 m from the treadmill to record the linear and temporal data. On the slope, stride length, stride duration, stance duration and swing duration did not change. However, midstep length increased significantly and the airborne step length decreased significantly as slope increased from a 3% slope to a 8% slope at 12 m/s. The airborne duration increased significantly from a 0% slope to a 3% slope, and inversely decreased significantly from a 3% slope to a 8% slope. The advanced placement (AP) between trailing hindlimb and leading hindlimb (APTH‐LH) and between trailing forelimb and leading forelimb (APTF‐LF) and the overlap between LH and TF (LH‐TF) tended to decrease and the AP between LH and TF (APLH‐TF) and the overlap between TH and LH (TH‐LH) inversely tended to increase as the slope increased, though these tendencies were not significant. These findings indicated that in slope locomotion, the stride length might be maintained by sacrificing the length of the airborne period as the workload became more intense.
Kinematics in horses at the trot before and after an induced forelimb supporting lameness
Authors: GALISTEO A. M. , CANO M. R. , MORALES J. L. , MIRÓ F. , VIVO J. , AGÜERA E.
Published: June 2010

The aim of this study was to analyse the biokinematic alterations caused by an induced lameness in the right forelimb of Dutch Warmblood (DWB) horses using a system of computer‐aided normal videography. Five mature DWB were recorded with a videocamera (frame rate 1/25) from a lateral view before and after an induced lameness. Before videotaping, passive markers were placed on the skin, over easily identifiable anatomical references to determine the joint angles in the forelimb (always on the flexor side). Lameness was induced using special horseshoes. The lameness was evident at the trot and mild at walk. The images were analysed using a real time digitalising system combined with a previously designed spreadsheet. Linear, temporal and angular parameters (maximum, minimum and angular range of motion) along the stride were calculated as well as the moments of highest extension (Pmax) and flexion (Pmin), expressed as a percentage of the whole stride. Results before and after the induced lameness were compared by a paired Student'sttest at a significance level of P<0.05. No differences in speeds before and after the induced lameness were found. Stride length was significantly shorter in the lameness condition. Stride duration was slightly shorter in lameness. The diagonal stance phase increased, while the swing phase decreased. Angular parameters changed mainly in elbow, carpus, fetlock and retraction‐protraction angles. This indicated that the angular range of motion in the elbow and carpal joints decreased, and the elbow Pmin occurred later in the stride. The results are useful in the development of video‐based equine lameness diagnostics.
Fetal pulmonary development: the role of respiratory movements
Authors: HARDING R.
Published: June 2010

The lung develops before birth as a collapsible, liquid‐filled, organ. Throughout the later stages of gestation the fetal lungs are maintained at a level of expansion that is considerably greater than the level achieved as a result of passive equilibration between lung recoil and the chest wall. Fetal breathing movements (FBM) are a feature of normal fetal life and, as such, are used clinically in the assessment of fetal wellbeing. By opposing lung recoil, FBM help to maintain the high level of lung expansion that is now known to be essential for normal growth and structural maturation of the fetal lungs. During ‘apnoeic’ periods between successive episodes of FBM, active laryngeal constriction has the effect of opposing lung recoil by resisting the escape of lung liquid via the trachea. The prolonged absence or impairment of FBM is likely to result in a reduced mean level of lung expansion which can lead to hypoplasia of the lungs. There is clinical evidence, disputed by some, that the absence of FBM exacerbates the effects of other factors that are associated with lung hypoplasia, such as premature rupture of fetal membranes and oligohydramnios. Even in the absence of such factors, prolonged or repeated reductions or abolition of FBM may contribute to impairments of fetal lung development; FBM can be inhibited by fetal hypoxaemia, hypoglycaemia, maternal alcohol consumption, maternal smoking, intra‐amniotic infection and maternal consumption of sedatives or narcotic drugs. Abnormal growth of the fetal lungs has relevance for postnatal respiratory health as it is now recognised that there may be only a limited capacity after birth for the restoration of normal pulmonary architecture following impaired intra‐uterine lung development.
Systemic and luminal influences on the perinatal development of the gut
Authors: TRAHAIR J. F. , SANGILD P. T.
Published: June 2010

At birth, the mammalian gastrointestinal tract (GIT) must be able to support a shift from mainly parenteral nutrition in the fetus (via the placenta) to enteral nutrition in the neonate. In the perinatal period the GIT therefore undergoes enhanced growth as well as morphological and functional differentiation, and this maturational programme is influenced by a complex interplay of local, systemic and luminal factors. This review shows how systemic and luminal factors may influence GIT development in the perinatal period of the pig and sheep, two long‐gestation species. Adrenocortical hormones play a pivotal role in the prepartum maturation of the GIT in addition to their better known effects on the development of many other tissues and body systems. More particularly, in the fetal pig and sheep, the prenatal development of gastric acid and gastrin secretion, and of GIT hydrolase activities (chymosin, pepsin, amylase, lactase, aminopeptidases) is influenced by Cortisol. Additionally, glucocorticoids exert effects throughout the GIT by influencing morphological, cytological, and functional differentiation. Since the GIT epithelial cells comprise a renewing cell population there are also changes in cell kinetics. In addition to systemic factors, the presence of growth factors, hormones and nutrients from swallowed amniotic fluid (fetus) and colostrum (neonate) may influence GIT development In utero, fetal fluid ingestion has been shown to modulate tissue growth, macromolecule and immunoglobulin transport, enterocyte differentiation, cell turnover and activity of brush‐border hydrolases. These effects may be mediated via regulatory peptides (e.g. insulin‐like growth factor I, gastrin‐releasing peptides, insulin, epidermal growth factor, gastrin). A physiological role of luminally derived growth factors is supported by a number of unique structural and functional adaptations of the GIT in the fetus and neonate (low luminal proteolysis, intestinal macromolecule transport). Thus, in the pig and sheep, both systemic and luminal factors appear to play critical roles in GIT development in the perinatal period.
Stimulation of the switch in myometrial activity from contractures to contractions in the pregnant sheep and nonhuman primate
Authors: NATHANIELSZ P. W. , GIUSSANI D. A. , WU W. X.
Published: June 2010

The process of parturition is regulated by a set of interrelated endocrine, paracrine, and autocrine systems. Many of these systems demonstrate positive feed‐forward characteristics. The sequential recruitment of signals that promote the labour process demonstrates that it is not possible to attribute the designation of the factor responsible for the ‘initiation of parturition’ uniquely to any one signalling mechanism. For this reason we prefer to avoid the term initiation of parturition since, mechanistically, each cellular and molecular mechanism that contributes to the process is itself initiated by an earlier process. In a very real sense, the initiation of parturition can be considered to be fertilisation. Therefore we prefer to describe the key mechanisms involved as promoting, rather than initiating, the process of labour and delivery. Despite many interspecies differences, an increase in maternal plasma oestrogen in late gestation appears to play a central role in promotion of parturition. In both sheep and monkeys signals from the fetal hypothalamo‐pituitary‐adrenal axis increase oestrogen production by the placenta. We propose that the key fetal adrenal product is Cortisol in the sheep and androgen in the monkey. Oestrogen then recruits a range of stimulators, uterotonins, that act on the prepared myometrium to initiate the switch in myometrial activity from contractures to contractions. The various mechanisms central to the process can be considered to be either, or both, activators and/or stimulators of one or more of the key terminal steps involved.
Biosynthesis and possible biological roles of progestagens during equine pregnancy and in the newborn foal
Authors: CHAVATTE PASCALE , HOLTAN D. , OUSEY JENNIFER C. , ROSSDALE P. D.
Published: June 2010

Major progress on the endocrinology of the pregnant mare has been possible thanks to the catheterised equine fetal preparation developed by Marian Silver. In particular, these preparations led to the identification of the source of progestagens within the feto‐placental unit and provided the impetus for further work on their biosynthesis and biological activities. The biosynthesis of the progestagens involves close interaction between the fetus, the endometrium and the placenta, and gives rise to some fundamental biochemical questions. The biological role of the progestagens is also discussed: these compounds may have progestagenic activities but may also play a role in the onset of parturition.
Long term exposure to T‐2 Fusarium mycotoxin fails to alter luteal function, follicular activity and embryo recovery in mares
Authors: JUHÁSZ JUDIT , NAGY P. , HUSZENICZA G. , SZIGETI G. , REICZIGEL J. , KULCSÁR M.
Published: June 2010

The effect of long term administration of T‐2 toxin was studied in 6 Trotter mares during the summer and early autumn. After one complete oestrous cycle (Cycle 1) each mare was given 7 mg purified T‐2 toxin perosdaily (1 mg/ml in ethyl alcohol) beginning on Day 10 after ovulation in Cycle 2. Exposure to toxin was continued for 32–40 days, until Day 7 of Cycle 4. During this period all the animals remained in good physical condition, but skin lesions were observed around the mouth in 3 cases. Toxin administration had no effect on the length of the interovulatory interval or on the lengths of the luteal and follicular phases. It also had no effect on peripheral plasma progesterone profiles or follicular kinetics, including the growth rate and maximum size of ovulatory follicles and the maximum number, and time of first increase in number, of follicles larger than 1 and 2 cm.

Uterine flushing was attempted in 5 mares and yielded 3 embryos (60%). These were of normal size and morphology and one was transferred nonsurgically to a recipient mare; a conceptus developed initially but it subsequently died and was resorbed. The results of the study allowed the conclusion that the administration of 7 mg/day T‐2 toxin to mares in good body condition has no detrimental effect on ovarian activity, fertilisation or oviductal transport.
Effects of follicular aspiration and flushing, and the genotype of the fetus on circulating progesterone levels during pregnancy in the mare
Authors: MEINTJES M. , GRAFF K. J. , PACCAMONTI D. , EILTS B. E. , PAUL J. B. , THOMPSON D. L. , KEARNEY M. T. , GODKE R. A.
Published: June 2010

When aspirating ovarian follicles in pregnant mares to obtain oocytes for in vitro fertilisation (IVF), the effect of the manipulation on circulating concentrations of progesterone may be an important consideration in terms of the maintenance of pregnancy. The object of this study was to compare the effects of 3 different forms of transvaginal ultrasound‐guided follicle aspiration (Treatment 1, no aspiration, n = 4; Treatment 2, aspirate only follicles >20 mm in diameter, n = 7; Treatment 3, aspirate all visible follicles, n = 7) on peripheral plasma progesterone concentrations between Days 21 and 150 of gestation in 9 mares carrying intraspecies horse and 9 mares carrying interspecies mule conceptuses. The 3 follicle aspiration treatments were applied at the peak of each follicular wave as determined by follicular mapping by means of transrectal ultrasonography on alternate days. The plasma progesterone profile in mares undergoing Treatment 1 was in close agreement with those reported previously in pregnant mares. A decline in plasma progesterone levels occurred after Day 53 of gestation in Treatments 2 and 3 mares, indicating that the follicular aspiration procedures did interfere with the formation of secondary corpora lutea. However, the levels in individual mares never dropped low enough to endanger the pregnancy. Mares carrying mule pregnancies exhibited higher mean plasma progesterone concentrations between Days 39 and 45 of gestation than mares carrying horse pregnancies, equivalent levels between Days 46 and 66 despite the lower circulating concentrations of chorionic gonadotropin (mule CG) in their blood during this period and lower progesterone levels between Days 67 and 150 of gestation. The results indicate that the primary corpus luteum in the pregnant mare may be more sensitive to mule CG than horse CG. Furthermore, the earlier disappearance of CG from the circulation in mares carrying mule fetuses is reflected by an earlier decline in plasma progesterone concentrations in this type of equine pregnancy.
Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously
Authors: BÉZARD JACQUELINE , MEKARSKA ANNA , GOUDET GHYLENE , DUCHAMP G. , PALMER E.
Published: June 2010

The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles ≤5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicles. Cumulus expansion of the preovulatory oocytes occurred at 12 h post LH treatment while the metaphase I and II components of nuclear maturation were not completed until 24 and 35 h post LH respectively. For nonpreovulatory follicles, the frequency of atresia and oocyte competence for in vitro nuclear maturation both increased with increasing follicular size.
Comparison of different methods for the recovery of horse oocytes
Authors: ALM H. , TORNER H. , KANITZ W. , BECKER F. , HINRICHS K.
Published: June 2010

The object of this study was to compare 4 different methods of oocyte recovery from mares; 1) transvaginal follicle aspiration in vivo; 2) follicle aspiration in vitro; 3) oocyte recovery by isolation of follicles in vitro and 4) follicle scraping in vitro. Oocyte recovery was highest after follicle scraping (71.1%) and follicle isolation and rupture (61.3%). Follicle aspiration in vitro and in vivo yielded oocytes on 31.2% and 19.3% of occasions, respectively. The output of different types of cumulus‐oocyte‐complexes was different among the methods; the portion of compact cumulus‐oocyte‐complexes was significantly higher with follicle scraping (50.7%) and follicle isolation (44.5%) than with aspiration in vivo (31.9%) and in vitro (23.7%). The recovery rate of oocytes from small follicles (<15 mm) was significantly higher than from larger follicles (P < 0.05) using transvaginal follicle aspiration. The proportion of oocytes that were degenerate (exhibited shrunken, dense or visibly damaged ooplasm) ranged from 1.2% after follicle scraping, to 17.2% after aspiration in vivo. These results indicate that, for the recovery of horse oocytes in vitro, follicle scraping and follicle isolation give the highest recoveries of cumulus‐intact oocytes.
Success rates when attempting to nonsurgically collect equine embryos at 144, 156 or 168 hours after ovulation
Authors: BATTUT I. , COLCHEN S. , FIENI F. , TAINTURIER D. , BRUYAS J.‐F.
Published: June 2010

The purpose of this study was to evaluate the exact age when the equine embryo reaches the uterus. The time of ovulation was determined by hourly ultrasound examinations starting 32 h after an injection of crude equine pituitary gonadotrophin or human chorionic gonadotrophin, or after the first of 4 injections of buserelin. Nonsurgical uterine flushings were carried out 144 h (Day 6), 156 h (Day 6.5) or 168 h (Day 7) after ovulation. Induction of ovulation was attempted in 101 oestrous cycles and 61 of 101 mares (60.4%) ovulated 32–44 h post injection. Sixty embryo collections were performed which yielded: 0/20 embryos at 144 h, 9/17 embryos (53%) at 156 h and 12/23 embryos (52%) at 168 h. The mean (± s.e.m.) diameter of the embryo was significantly greater (P < 0.01) at Day 7 (244 ± 15 μm) than at Day 6.5 (186 ± 9.1 μm), and variability in size was observed among embryos collected from the same mare after synchronous natural multiple ovulations.

These results suggest that; i) horse embryos enter the uterus between 144 and 156 h after ovulation, and ii) the time interval between ovulation and fertilisation in mares is inconsistent and/or embryonic development rate may differ between individual embryos.
Parentage testing of Day 10 equine embryos by amplified PCR analysis of microsatellites
Authors: GUÈRAND MATHILDE , MAHLA R. , LAGNEAUX D. , AMIGUES Y. , PALMER E. , BÉZARD JACQUELINE
Published: June 2010

Paternity analysis was performed on the DNA of 21 equine embryos collected nonsurgically 10 days after ovulation from known mares, but involving 3 possible sires. After extraction, the DNA of each embryo was typed by radioactive PCR amplification using 10 characterised microsatellites; HMS 1, 2, 5, 6, 7 and 8 (Guérin et al. 1994) and HTG 3, 4, 6 and 10 (Marklund et al. 1994). The 21 dams and 3 sires were genotyped using DNA extracted from blood and amplified by PCR. After electrophoresis and autoradiography of the PCR products of the embryo and parents, the alleles of the embryo were compared to those of the dam to identify those of maternal origin. The paternal alleles were then searched for within the genotype of the 3 sires, and the stallion(s) that exhibited the particular allele was said to be compatible with the embryo for this microsatellite. In this way, the true sire was identified correctly for all 21 embryos.
The effect of propanediol on the morphology of fresh and frozen equine embryos
Authors: BRUYAS J‐F. , MARTINS‐FERREIRA C. , FIÉNI F. , TAINTURIER D.
Published: June 2010

Seventeen horse embryos recovered on the sixth day after spontaneous ovulation were; 1) washed in PBS (n = 6), 2) treated with 1.5 M 1–2 propanediol (n = 6) or, 3) frozen and thawed using 1.5 M propanediol as the cryoprotectant (n = 5). After treatment, the embryos were incubated for 6 h in medium before they were fixed, serially sectioned and examined microscopically to count the total numbers of interphase, mitotic and pycnotic nuclei. Significant differences were measured only in the mean proportions of pycnotic cells (± s.d.), both between the control (9.2 ± 7.3%) and frozen‐thawed embryos (52.8 ± 37.1%; P < 0.05) and between the propanediol‐treated (10.8 ± 4.6%) and the frozen‐thawed embryos (P < 0.01). Propanediol appears to be minimally toxic to equine embryos but it is a poor cryoprotectant.