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Equine water treadmills (WT) were initially designed for rehabilitation of musculoskeletal injuries, but are also commonly used for conditioning sport horses, however the effects are not well documented. The purpose of this study was to test the effect of an 18-day WT conditioning programme on peak oxygen consumption (V̇O 2 peak). Nine unfit Thoroughbreds were used in a randomised controlled trial. Six horses worked daily for 18 days in stifle-height water (WT group), while 3 control horses worked without water (dry treadmill group (DT)). Preconditioning and postconditioning maximal exercise racetrack tests (800 m) were performed using a portable ergospirometry system. Measured outcomes were V̇O 2 , tidal volume, minute ventilation, breathing frequency, heart rate, blood lactate and instantaneous and average speed. The workload as assessed by V̇O 2 was 21.7 per cent of preconditioning V̇O 2 peak values for WT horses. V̇O 2 peak on the racetrack increased by 16.1 per cent from preconditioning to postconditioning in the WT horses (P=0.03), but did not change in the DT horses. Therefore, exercising horses in high water heights may improve conditioning., Competing Interests: Competing interests: None declared., (© British Veterinary Association 2020. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)

The objectives of this report were to describe the occurrence and features of dynamic ventrorostral displacement of the dorsal laryngeal mucosa (VRDDLM) in a group of Thoroughbred horses presented for investigation of poor performance and/or abnormal respiratory noise. Records from 600, dynamic, endoscopic examinations of the upper respiratory tract of horses were reviewed. Horses with VRDDLM were identified as those in which the dorsal laryngeal mucosa progressively obscured the interarytenoid notch and dorsoaxial portion of the corniculate processes of the arytenoid cartilages during high-speed exercise. The condition was recognised in 12 horses. Concurrent abnormalities of the respiratory tract of eight horses were also identified and included, axial deviation of the aryepiglottic folds, vocal cord prolapse, unilateral and bilateral ventromedial luxation of the apex of the corniculate process of the arytenoid cartilage, and intermittent dorsal displacement of the soft palate. VRDDLM is a rare abnormality of the upper portion of the respiratory tract of horses that may be associated with abnormal respiratory noise and potentially poor performance. The significance of the condition is not known, but the presence of this condition in combination with other, obstructive diseases of the equine airway warrants further investigation.

Thirty-eight endurance horses underwent clinical and ancillary examinations, including haematological and biochemical evaluation, standardised exercise tests both on a treadmill and in the field, Doppler echocardiography, impulse oscillometry, video endoscopy and collection of respiratory fluids. All of the examined poorly performing horses were affected by subclinical diseases, and most of them had multiple concomitant disorders. On the contrary, the well-performing horses were free of any subclinical disease. The most frequently diagnosed diseases were respiratory disorders, followed by musculoskeletal and cardiac problems. Poor performers exhibited lower speeds at blood lactate concentration of 4 mmol/l (VLA4) and at heart rates of 160 (V160) and 200 bpm (V200) on the treadmill and in the field, as well as slower recovery of heart rate.

The objective of this study was to evaluate the effects of extracorporeal radial shock wave therapy on the hindlimb function of dogs suffering from hip osteoarthritis. Twenty-four client-owned dogs with hip osteoarthritis were investigated; 18 of them received radial shockwave therapy and six were left untreated as controls. Force plate analysis on a treadmill was used to assess the dogs' hindlimb function before treatment and four weeks after the last treatment, and the treated dogs were re-evaluated three and six months after the treatment. The parameters chosen for evaluation were peak vertical force and vertical impulse, and the calculated symmetry indices. In the treated dogs, differences between the ground reaction forces exerted by the right and left hindlegs disappeared four weeks after the treatment, whereas in the control dogs only the peak vertical force distribution changed significantly. The significant improvement in the treated dogs was confirmed by changes in the symmetry indices. Significant improvements in vertical impulse and peak vertical force were observed three months after the treatment.

The kinetic parameters of the limbs of 23 normal, client-owned cats were evaluated by encouraging them to walk and jump normally on a pressure-sensitive walkway. Each cat was encouraged to walk across the walkway five times over a period of 30 to 45 minutes (by using food, toys, the owner's presence and a purpose-built tunnel) at a target speed of 0.6 m/s (and an acceleration of less than +/- 0.1 m/s(2)). They were then encouraged to jump on to the walkway from a height of 1 m five times at five-minute intervals. The kinetic parameters of peak vertical force (PVF) and vertical impulse (VI) were measured for each limb (the forelimbs only for the jumps), and expressed as a percentage of bodyweight (PVF(%BW) and VI(%BW/S)). Fifteen of the 23 cats satisfactorily completed three to five walks and two to five jumps that could be analysed. There were no significant differences between the PVF or VI of the left and right limbs, but both parameters were significantly greater for the forelimbs than the hindlimbs (P<0.001) for the walking data. The mean (sd) PVF(%BW) for the forelimbs and hindlimbs were 48.2 (6.0) and 38.3 (4.0), respectively, and the mean VI(%BW/s) were 16.9 (3.2) and 13.3 (2.8). Jumping down generated significantly greater PVF (P<0.01) and slightly greater VI than during walking; there were no significant differences between the left and right forelimbs. The mean PVF(%BW) was 148.9 (16.4) and the mean VI(%BW/s) was 18.1 (4.3).

The trotting gait of 10 sound, adult labrador retrievers was analysed using kinematic gait analysis on a purpose-built treadmill using video-based motion analysis software. The maximal angular displacement, minimal angular displacement, average angular displacement, and the maximal positive and negative angular velocities of the right elbow and right stifle were measured over five gait cycles at defined time points during each of five two-minute sessions. The dogs' trotting gait was not repeatable, either for individual dogs during the first session or between sessions, or between dogs at the same time points during a session.

The relationships between V4 (the velocity for a blood lactate concentration of 4 mmol/litre) and V200 (the velocity for a heart rate of 200 bpm) and the performance indices of 223 healthy French trotters were analysed. They were divided into four age groups of three, four, five and six years and over, and into three performance groups (good, intermediate and poor performers) defined by the index of trot (ITR), an annual index of performance calculated by the national stud. V4 and V200 were assessed during the performance of a three-step standardised field exercise test, and four performance indexes (ITR, earnings, best time and the number of starts) were calculated for each group. An analysis of variance showed that V4 and V200 were highly correlated with the horses' age and level of performance (P<0.05). The correlation between the physiological variables and ITR was better for the three- and four-year-old horses than for the older horses.

The responses in heart rate, plasma lactate and rectal temperature of standardbred trotters to draught loaded interval exercise on a treadmill and a race track were studied. The horses were exercised with incrementally increasing trotting speeds for two-minute intervals with draught loads of 10, 20 and 30 kilopond (kp) in three different tests. Each trotting interval was followed by two-minute periods at a walk without a draught load. Measurements of heart rate and plasma lactate were made at the end of each interval and the rectal temperature was taken at the end of the exercise. The heart rate and plasma lactate levels were significantly lower on the treadmill than on the track in the tests with 10 kp, but no significant differences were found between the treadmill and track exercise tests with the heavier draught resistances. No differences were observed in rectal temperature between treadmill and track conditions. From these findings it was concluded that the workload was significantly greater on the race track compared to the treadmill when the draught resistance was low (10 kp). Although the workload increased on both the race track and the treadmill as draught resistance increased, at the heavier draught resistances track exercise was no longer more demanding than exercise on the treadmill.

A method for the continuous monitoring of the electrocardiogram (ECG) of horses at rest and during exercise was evaluated in five healthy horses. The horses spent 24 hours in a loose box and performed a standardised exercise test on a treadmill during this period. Two bipolar leads were recorded, lead 1 between the xiphoid and the left withers, and lead 2 between the left ventral thorax and the left dorsal thorax, using disposable electrodes. The quality of the ECGs enabled both an 'operator-controlled' and an automatic analysis to be made. Lead 1 was the most stable during exercise and lead 2 during rest in the loose box. The heart rate and occurrence of arrhythmias were assessed over 22 hours. During the boxed period the heart rate varied from 31 +/- 2 to 138 +/- 11 beats per minute (bpm) and during exercise it varied from 79 +/- 8 to 177 +/- 12 bpm. All the horses had sinus arrhythmias, sinus tachycardias and second degree atrioventricular blocks. One horse developed a ventricular escape rhythm.

Six Dutch warmblood horses, ridden by an experienced rider, cantered 3320 m at a speed adapted to the individual horse's anaerobic threshold, under four different conditions: 1, on a firm shell track with the speed varying from 6.5 to 9.4 m/s; 2, on a horizontal treadmill at the same speeds and for the same duration as in test 1; 3, on a horizontal treadmill for the same duration as in tests 1 and 2, but at a 10 per cent higher speed; and 4, on a treadmill at the same speed and for the same duration as in test 1, but at an inclination of 1 to 2 per cent adjusted individually to obtain heart rates similar to those recorded in test 1. On the basis of the heart rates and plasma lactate concentrations, the workload of the horses was significantly greater in the normal exercise test (1) than in the first treadmill test (2). Increasing the speed of the test on the horizontal treadmill by 10 per cent (test 3) resulted in heart rates and plasma lactate concentrations similar to those recorded in test 1. Inclining the treadmill on the basis of the heart rates achieved in test 1 had a less consistent effect than increasing the speed, but imitated a normal exercise test better than the horizontal treadmill test 2.

Ten horses underwent a standardised strenuous treadmill exercise test, before, during and after which measurements were made of plasma beta-endorphin and cortisol concentrations, blood lactate, glucose, haemoglobin and pH, the activities of creatine kinase, lactate dehydrogenase and aspartate amino-transferase, and heart rate, oxygen uptake and expired minute volume. The correlations between the exercise-induced response of beta-endorphin and the changes observed in the other physiological measurements were examined. There was a large variation in the beta-endorphin response of the horses to exercise. The increase in beta-endorphin was correlated significantly and inversely with the treadmill velocity at which maximal oxygen uptake was reached. It was also significantly and directly correlated with the heart rate during recovery, the increase in plasma lactate concentration and the change in blood pH, indicating that the exercise-induced increase in beta-endorphin concentration was smaller in horses with a higher aerobic capacity.

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)

Stallions selected by the Royal Dutch Warmblood Society were submitted to a standardised lungeing test at the beginning and at the end of a 100-day test of performance and ability. The heart rate, haematology and biochemistry values obtained in the first lungeing test showed no significant differences between the 15 stallions which were rejected by the Royal Dutch Warmblood Society during the first month of the 100-day test, the 15 stallions rejected during the last month and the 11 stallions which were approved for registration in the studbook. The 26 stallions submitted to the second lungeing test had significantly lower heart rates and blood lactate concentrations than in the first test. The standardised lungeing test had no value in predicting the rejection or approval of the stallions, and the fitness of a stallion at the beginning of the 100-day test did not influence its chance of being approved as a breeding stallion. The differences between the results of the first and the second tests suggest that the fitness of the stallions improved during the 100-day test.

In a crossover study, either a placebo paste or N,N-dimethylglycine was administered orally at a dose rate of 1.2 mg/kg twice daily for five days to six thoroughbred horses, with bodyweights ranging from 424 to 492 kg. Using previously determined regression equations for oxygen uptake (VO2) against speed for each horse, a standardised exercise test was given with speeds equivalent to fixed percentages of the maximum oxygen uptake (VO2max). The test consisted of two minutes at speeds equivalent to approximately 40 per cent and 50 per cent VO2max, and one minute at speeds that produced approximately 60, 70, 80, 90 and 100 per cent VO2max. During the last five seconds of each exercise stage, the values of VO2, carbon dioxide production (VCO2), heart rate, arterial blood and plasma lactate concentrations, arterial blood gases and pH were measured. Before and immediately after the exercise test, muscle biopsies were collected from the middle gluteal muscle to determine the muscle lactate concentrations. The administration of N,N-dimethylglycine produced no significant differences in any of the measured values, and it is concluded that the compound has no beneficial effects on cardiorespiratory function or lactate production in the exercising horse.