Effects of a synthetic all-weather waxed track versus a crushed sand track on 3D acceleration of the front hoof in three horses trotting at high speed.

REASONS FOR PERFORMING STUDY: Inadequate track surfaces are believed to be a risk factor in the occurrence of musculoskeletal injuries, but quantification of the shocks and vibrations provoked by hoof impact on different ground surfaces (including new synthetic tracks) has been insufficiently documented in trotters under high-speed training conditions. OBJECTIVES: To test the reliability and sensitivity of an accelerometric device to discriminate between the biomechanical effects of 2 different tracks at high speed. METHODS: Three French Trotters were used and their right front hooves were equipped with one triaxial accelerometer. Two different track surfaces (crushed sand track: S and all-weather waxed track: W) were tested when horses were trotting in a straight line. For each session of measurements, trials were repeated 3 times in a Latin square design. The speed of the runs was set at 10 m/s, controlled by the driver and recorded synchronously. Sample rate was set at 6 kHz. Acceleration of the hoof (resultant vector and 3D components), power spectral density at impact and variability (between strides, trials, sessions and horses) were analysed. Statistical differences were tested using a GLM procedure (SAS). Least square mean differences were used for comparisons between tracks (P < 0.05). RESULTS: Results showed that the deceleration of the hoof (magnitude of the resultant vector) was statistically different between the 2 tracks with an attenuation of the shock of about 50% on the all-weather waxed track. Magnitude of the power spectral density was reduced at higher frequencies on W. CONCLUSIONS AND CLINICAL RELEVANCE: These preliminary results demonstrate the sensitivity of the tool to discriminate between the different behaviours of the hoof on the different track surfaces at high speed. Deceleration and vibration of the hoof at impact were reduced on W compared to S, suggesting a better shock-absorbing quality of this track.

Use of a 3D dynamometric horseshoe to assess the effects of an all-weather waxed track and a crushed sand track at high speed trot: preliminary study.

REASONS FOR PERFORMING STUDY: Track surface quality is considered a risk factor of musculoskeletal injuries. Ground reaction force (GRF) measurement is a relevant approach to study the interaction between the hoof and the ground. Force plates are not adapted to compare different surfaces at high speed. A 3D dynamometric horseshoe (DHS), using 4 triaxial piezoelectric sensors, has been developed and validated. OBJECTIVES: To use the DHS to compare the effects of 2 track surfaces, an all-weather waxed track and a crushed sand track, on the GRF in trotter horses under training conditions. METHODS: The right forelimb of 3 French Trotters was equipped with the DHS. Two tracks were tested in a straight line: a crushed sand track (S) and an all-weather waxed track (W). For each session, trials were repeated 3 times in a Latin square design. The speed of the runs was set at 10 m/s and recorded synchronously. For each trial, data acquisition was performed at 600 Hz and 10 consecutive strides were analysed. Statistical differences were tested using a general linear model procedure. RESULTS: The amplitude of the maximal longitudinal braking force (Fx) was significantly lower on W compared to S. This event happened about 6% later in the stance phase on W. The magnitude of the GRF at impact decreased on W. The average speed and the mean stance phase duration were not statistically different on both surfaces. The stride length was about 6 cm longer on S. CONCLUSION AND POTENTIAL RELEVANCE: This study demonstrates the ability and sensitivity of the DHS to discriminate track surfaces by measuring the GRF at high speed. These preliminary results show that the loading rate, the amplitude of horizontal braking and shock at impact are attenuated on W, which suggests a reduction of stresses in the distal limb.

Influence of track surface on the equine superficial digital flexor tendon loading in two horses at high speed trot.

REASONS FOR PERFORMING STUDY: Although track surfaces are a risk factor of tendon injuries, their effects on tendon loading at high speed are unknown. Using a noninvasive ultrasonic technique, it is now possible to evaluate the forces in the superficial digital flexor tendon (SDFT) in exercise conditions. OBJECTIVES: To compare the effects of an all-weather waxed track (W) vs. a crushed sand track (S), on the SDFT loading in the trotter horse at high speed. METHODS: Two trotter horses were equipped with the ultrasonic device (1 MHz ultrasonic probe, fixed on the palmar metacarpal area of the right forelimb). For each trial, data acquisition was made at 400 Hz and 10 consecutive strides were analysed. In each session, the 2 track surfaces were tested in a straight line. The speed was imposed at 10 m/s and recorded. The right forelimb was also equipped with a dynamometric horseshoe and skin markers. The horse was filmed with a high-speed camera (600 Hz); all recordings were synchronised. Statistical differences were tested using the GLM procedure (SAS; P < 0.05). RESULTS: Maximal tendon force was significantly lower on W compared with S. In addition to maximal force peaks around mid-stance, earlier peaks were observed, more pronounced on S than on W, at about 13% (horse 2) and 30% (both horses) of the stance phase. Comparison with kinematic data revealed that these early peaks were accompanied by plateaux in the fetlock angle-time chart. For high tendon forces, the tendon maximal loading rate was significantly lower on W than on S. CONCLUSIONS AND POTENTIAL CLINICAL RELEVANCE: The all-weather waxed track appears to induce a lesser and more gradual SDFT loading than crushed sand. The SDFT loading pattern at high speed trot suggests proximal interphalangeal joint movements during limb loading.

The measurement of ground reaction force in dogs trotting on a treadmill: an investigation of habituation.

We studied the time necessary to obtain reliable kinetic data from healthy dogs trotting on a treadmill. Ten adult male Malinois Belgian Shepherd dogs were made to trot on an instrumented treadmill to record the ground reaction force for the entire body and to determine the vertical force variables (peak [PFz], impulse [IFz], stride time [Str], peak time [Tz] and contact time [Ct]). Data were collected from each dog, during three sequences per day, on three consecutive days. In order to determine the contribution of the sequence, day of measurement, and dog factors and the percentage of variance attributable to dogs, data were analyzed with a linear mixed model. The curve shapes were similar to those obtained with a floor-mounted force platform. Intra-dog coefficients of variation were between 1.57 and 3.46%. Inter-dog coefficients of variation were between 4.18 and 7.82%. A sequence effect was not noted. Each day had a significant effect on all of the data. All variables differed significantly from the first day compared to the other days. However there was not any difference between days 2 and 3. The percentage of the total variance attributable to dogs ranged from 37 to 88%. The coefficients of variation were lower than those obtained with common protocols. The treadmill locomotion remained consistent during a single session. Even if interday variation needs to be accounted for, reliable data can still be obtained after a single training session. The majority of the variation was attributable to the dog. An instrumented treadmill may be used for kinetic analysis.

The effects of treadmill inclination and speed on the activity of two hindlimb muscles in the trotting horse.

Electromyographic activity (EMG) was used to determine how hindlimb muscle activation patterns vary with speed and incline in the horse. EMG was recorded using surface electrodes over the gluteus medius and tensor fasciae latae muscles during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and inclination (0, 3 and 6%). Raw EMG signals were processed to determine stride duration, activity onset and end, and integrated EMG (IEMG). Stride and stance phase duration decreased linearly with increasing speed. Stride duration was not influenced by the slope. Onset and end of muscle activity came significantly earlier in the stride cycle when speed increased and later when inclination changed from 0 to 6%. The relative duration of the burst (percentage of stride duration) increased as running speed increased, but tended to decrease with increasing slope. The IEMG of the muscles increased with increasing speed and slope, the largest increase being observed in the tensorfasciae latae. It is concluded that both increases in speed and inclination lead to an increase in the integrated electromyographic activity and hence to a higher workload of the 2 hindlimb muscles investigated.

The effects of treadmill inclination and speed on the activity of three trunk muscles in the trotting horse.

The purpose of this study was to evaluate the effects of speed and slope on the activity of trunk muscles. The electromyographic (EMG) activity of the splenius (Sp), longissimus dorsi (LD) and rectus abdominis (RA) muscles was recorded with surface electrodes during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and slope (0 to 6%). Raw EMG signals were processed to determine activity duration, onset and end and integrated EMG (IEMG). For the 3 muscles investigated, onset and end of activity were obtained earlier in the stride cycle when speed increased. A longer duration of activity for the LD, a shorter duration for the RA and an unchanged duration for the Sp were also observed. The IEMG of the latter was poorly affected by speed, whereas it increased linearly with speed for the 2 other muscles. When treadmill inclination changed from 0 to 6%, EMG activity of the LD and RA began and ended later; a longer activity duration was noted. Temporal parameters for Sp did not change with slope. A significant and progressive increase in the IEMG of the 3 muscles was observed with increasing slope. This evaluation of the activity of trunk muscles provides objective data for the use of speed or slope in training programmes.

Physiological variables measured under field conditions according to age and state of training in French Trotters.

We hypothesised that the derived physiological variables V2 and V4 (velocity to achieve a blood lactate concentration of 2 and 4 mmol/l, respectively), HR2 and HR4 (the corresponding heart rate) and V200 (the velocity for a heart rate of 200 beats/min) would improve with training state and age, in French Trotters. A total of 194 French Trotters from one training establishment were followed for 6 years and 1105 standardised field exercise tests performed on a sand training track. The horses were divided into 6 age groups (from 1 to > or = 6 years) and 4 training groups (beginning, endurance training, sprint training, racing). A 2-way analysis of variance was performed to evaluate the effects of age, training and the interaction of age and training on these physiological variables with the level of statistical significance set at 5%. The results showed that there was a significant influence of age on HR4, V2, V4 and V200, with these variables increasing with age. Also, there was a significant influence of training and both age and training on V2, V4 and V200, with these variables increasing with training and age. These results, obtained in a longitudinal study in a reproducible field environment, are consistent with previous laboratory-based experimental studies. We conclude that objective indices of fitness obtained on the training track can be useful in the commercial training environment.

Comparison of some responses to exercise on the track and the treadmill in French trotters: determination of the optimal treadmill incline.

The purpose of this study was to determine the optimal treadmill slope for trotters to produce the same heart rate and blood lactate responses as on the track during a standardized exercise test. Nine 2-year-old French trotters performed exercise tests on a training track and on a treadmill set at an incline of 0, 2 or 4%. For all horses, track testing was performed on day 1 and then on the treadmill according to a Latin-square design. The track test utilized three steps each of 3 min at speeds of 470, 530, 590 m/min and the same speeds were used on the treadmill. Derived physiological variables such as the speed at a HR of 200 bpm (V(200)) and the speed inducing blood lactate concentrations of 4 mmol/L (V(4)) were calculated. There were significant differences for V(200)and V(4)(P<0.05) between the track and the treadmill data when the treadmill was set at inclines of 0 and 4%, but no significant differences with the treadmill set at a 2% incline. The optimal treadmill incline to reproduce similar responses to those on the track was determined by regression analysis, and was found to be 2.4% for the two most often utilized derived physiological variables, V(4)and V(200).

Determination of the optimal treadmill slope for reproducing the same cardiac response in saddle horses as overground exercise conditions.

The purpose of this study was to define the most suitable treadmill slope for reproducing the same heart rate response as in horses being ridden on a track. Seven French saddle horses were exercised first on a level turf track and then on a treadmill. On the track the exercise test consisted of four periods of three minutes of increasing speeds at the trot and the gallop (96 to 600 m/minute). The treadmill exercise tests consisted of seven steps of increasing slope (0 to 9.6 per cent) at the trot (252 m/minute), followed, after an active recovery period at the walk with a 0 per cent slope, by five steps of increasing slope for two minutes each (0 to 6.3 per cent), at the gallop at 493 m/minute. The mean heart rate at each step of the exercise tests was measured with a heart rate recorder. On the exercise track there was a strong linear relationship (R = 0.89, P < 0.01) between heart rate and speed. The heart rate response of the horses exercised at different speeds and slopes on the treadmill was best fitted (R = 0.96, P < 0.01) by a multilinear model. The optimal treadmill slope was determined by equalizing the equations derived from the two tests: s = -0.001 V + 3.658. It was concluded that the optimal treadmill slope ranged between 3.0 and 3.7 per cent. In order to verify this result, a comparison was made between the heart rate response of the horses during the same incremental exercise test performed on the track and on the treadmill with a 3.5 per cent slope.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diagnostic and therapeutic strategy in carcinoma of the extrahepatic bile ducts]. / Stratégie diagnostique et thérapeutique des carcinomes des voies biliaires extra-hépatiques.

The preoperative diagnostic approach in 25 patients with bile duct carcinoma was studied. Investigation procedures included gray-scale ultrasonography with guided fine needle biopsy of focal lesions, percutaneous transhepatic or retrograde cholangiography, transhepatic biliary drainage with brush and forceps biopsy of biliary stenosis as well as selective angiography for feasibility of surgical resection. Diagnosis was ensured in 23 patients by cytologic or histologic tissue specimens. Twenty-one lesions were judged unresectable on the basis of bile duct or vascular tumor extension and patient status. These patients were treated either by iridium 192 wire radiation therapy (6 cases) or by nonsurgical biliary drainage. Four patients with a potentially resectable tumor underwent surgery. This preoperative diagnostic approach can be recommended for selecting appropriate therapy in patients with bile duct carcinoma.

Evolution of radiological findings detected in the limbs of 321 young horses between the ages of 6 and 18 months.

The objective of this study was to evaluate the spontaneous evolution of radiological findings (RF) indicative of juvenile osteochondral conditions (JOCC) in a field study. A radiographic survey was performed at the age of 6 and 18months in 321 young horses from three breeds (French Trotter Standardbred, Selle-Français Warmblood and Thoroughbred). Each RF identified at 6months was re-evaluated at 18months, and classified as (1) disappeared, (2) improved, (3) stable, (4) deteriorated or (5) new when it was not identified at 6months. Only 32.3% of all RF identified at the age of 6months were stable, while at 18months 46.6% had disappeared and 38.7% were new radiological abnormalities. Evolution of RF varied according to the joint involved and the type of lesion. In the stifle, 85.7% of the RF of osteochondral fragmentation (OCF) of the lateral ridge of the femoral trochlea regressed (disappeared or improved). In the hock, 53.1% of the RF of OCD of the intermediate ridge of the tibial cochlea were stable. In the fetlock, dorsal and plantar OCF were frequently observed as new radiological abnormalities at 18months (51% of the dorsal RF and 45.8% of the plantar). As many lesions develop or change after 6months, a definitive radiographic assessment of the JOCC status is more reliable at 18months. Knowing the spontaneous healing capacity of some lesions is useful in helping to decide the appropriate management.

Longitudinal development of equine forelimb conformation from birth to weaning in three different horse breeds.

There is limited published data on conformational changes in the forelimbs of growing foals. This study was designed to describe the changes in conformation of the carpus and distal forelimb from birth to weaning in foals of three different breeds. Evaluation of the conformation of the carpus, fetlock, pastern and foot was carried out in 134 Thoroughbreds, 162 French Trotters and 98 Selle Français (French Warmblood) within 1 month of age and then at approximately 2 month intervals until weaning at approximately 6 months of age. The prevalence of limb deviations decreased from birth to weaning. Angular limb deformities were the predominant conditions in the first month (63.6% of all observed limb deviations) and flexural limb deformities were the most common abnormalities at weaning. The most frequent congenital abnormalities were carpal valgus (42.1% of the foals), fetlock valgus (31.2%), over-at-the-knee (30.8%) and dropped fetlocks (13.0%), with French Trotters and Thoroughbred foals being more affected than Selle Français foals. During the study period, the carpal and fetlock conformation became less valgus. The predominant abnormalities at weaning were fetlock valgus (19.1%), club feet (13.0%) and fetlock varus (11.2%). These observations show that carpal, fetlock and foot conformations changed substantially from birth and weaning. There were significant conformational differences between the three breeds, especially in the first months of life. An understanding of the peculiarities of specific breeds may be useful for the evaluation of individual foal conformation.

Radiographic findings of juvenile osteochondral conditions detected in 392 foals using a field radiographic protocol.

Radiographic examination in young horses is commonly used to detect juvenile osteochondral conditions (JOCC). The aim of this study is to present the radiographic findings (RF) detected at the age of 6months in the joints of 392 foals from three breeds: French Trotter Standardbreds (FT), Selle-Français Warmbloods (SF) and Thoroughbreds (TB). Radiographic examination included lateromedial views of the fore and hind digits, tarsi and stifles, and dorsopalmar projections of both carpi. In all areas RF indicative of JOCC were classified according to a four-grade severity scoring system. Distribution and severity of the RF varied according to breed with the SF most affected. The most frequently affected site was the hind fetlock (28.3% of foals). The second most affected site was the fore fetlock in TB and SF, while the carpus and proximal tarsus were the second and third affected sites in FT. The radiographic protocol and grading system used can serve as a basis for field research and further studies on the evolution of RF, risk factors for JOCC or the correlation between RF and the subsequent athletic career of horses.

Genetic parameters of juvenile osteochondral conditions (JOCC) in French Trotters.

Juvenile osteochondral conditions (JOCC) have been defined as lesions resulting from biomechanical influences (compressive, tensional or shear forces) on the developing and growing musculoskeletal system. They include different types of osteochondrosis, osteochondral fragmentation of the articular surface or of the periarticular margins, juvenile subchondral bone cysts, osteochondral collapse, avulsion fractures of epiphyseal (or metaphyseal) ossifying bone and 'physitis'. The aim of this study was to estimate heritability of JOCC in a sample of 2106 French Trotters from four different sources, comprising representative samples of the Trotter population, as well as material from auctions. Horses were aged 6-24months and were either not yet in training or just beginning training. Radiographs were taken of fore and hind feet, including proximal interphalangeal (pastern) joints, metacarpophalangeal and metatarsophalangeal (fetlock) joints, tarsocrural (hock) joints, carpi and femoropatellar (stifle) joints. The threshold model used included sex, age, region and month of birth, sampling group and sire (n=159) with all inter-sire relationships. The main results were a moderate heritability for findings in the hind fetlock (0.29) and the hock (0.19). There was a weak genetic correlation between findings in fetlocks and hocks (0.26). Higher heritability was found for findings in the hock (0.37 for findings in the distal row and 0.49 for the proximal row of tarsal bones) in that part of the data (699 horses) in which it was possible to integrate the grade, bilateral occurrence or not, and distal or proximal location of the lesions. It is possible to use these genetic parameters in breeding selection with more efficiency when detailed phenotypes are considered.