Classic descriptions of rib motion during ventilation include three-dimensional movements that are tied to the locomotor pattern. It is still not clear how chest wall and diaphragmatic movements contribute to ventilation. The purpose of this paper was to evaluate how gait affects local thoracic geometry in horses. Hemispherical markers were placed on the skin over the ribs and spine to calculate thoracic hemi-diameter. Ventilatory airflows were recorded using an ultrasonic flowmeter system. Airflow and kinematic data were collected synchronously at walk (1.8 m s-1), trot (4 m s-1), canter and gallop (6, 8 and 10 m s-1) on the treadmill. At walk and trot, the changes in right and left hemi-diameter were approximately symmetric. At walk, mean hemi-diameter changes were 40 mm (rib 10) and 47 mm (rib 16). At trot, they were 33 mm (rib 10) and 34 mm (rib 16). Across the three canter and gallop speeds, leading (right) side hemi-diameter change increased from 25 to 30 to 35 mm (rib 10) and from 23 to 37 to 46 mm (rib 16). The trailing (left) side hemi-diameter increased from 50 to 67 to 70 mm (rib 10) and from 36 to 48 to 54 mm (rib 16) (P≪0.01). At canter and gallop, the non-lead side of the thorax is subjected to larger amplitude changes in hemi-diameter than the lead side, which tends to be more compressed overall and demonstrates smaller amplitudes of change in diameter.

The study aimed to investigate the effect of speed and incline on EMG activity in the brachiocephalicus muscle and the long and lateral heads of the triceps brachii muscle. Six horses were exercised on a treadmill at walk (1.7 m s-1), trot (4.0 m s-1) and right lead canter (7.2 m s-1) on a 0 and 8% incline. Kinematics (120 Hz) and electromyography (EMG) (2000 Hz) data were collected simultaneously from the left forelimb of each horse. Significant differences in relation to velocity and incline were identified using two-way ANOVA and post hoc Student–Newman–Keuls tests (P≪0.05). The degree of association between timing of peak EMG intensity and the timing of maximum protraction/retraction angles was assessed using ANCOVA. Increases in velocity led to an increase in stride length and reduction in stride duration. Exercise on the incline increased stance duration and decreased swing duration, while limb protraction/retraction increased. The time of peak EMG activity in the brachiocephalicus was highly related to time of maximum limb retraction (r2=0.84). The time of peak EMG activity in the long head of the triceps brachii was highly associated with time of maximum limb protraction (r2=0.87). Increases in velocity and incline both caused an increase in the intensity of the EMG signal from each muscle. Duration of EMG activity was prolonged in the long head of the triceps brachii muscle and in the brachiocephalicus muscle as velocity increased. Treadmill speed and slope therefore both alter the workload placed on forelimb muscles.

This study tested the hypothesis that exercise training would alter feed intake (FI), body composition (BC) and plasma concentrations of active ghrelin, leptin, cortisol, insulin and glucose. Eight Standardbred mares (12±2 years, 509±36 kg body weight (BW), mean±SD) were trained (EX) in an equine Equi-ciser (initially 3 days per week at 60% maximal heart rate (HRmax) for 20 min and gradually increased to 5 days per week at 70% HRmax for 30 min, with a 10-min warm-up and 10-min cool-down period at the walk). Six mares (12±2 years, 537±45 kg) served as non-exercise controls (CON). All mares were unfit and had not been subjected to conditioning for 3 years before the experiment. Pre- and post-training incremental exercise tests (GXT) were run to determine HRmax and maximal oxygen uptake (VO2max). A total mixed ration (TMR) of hay cubes was fed free choice for 16 h day-1 with the primary experiment following a 6-week diet adaptation period. Mares' FI was measured daily and reported in grams per kilogram BW of feed eaten per week. Changes in BC were assessed using BW (electronic scale) and percentage fat calculated using rump fat thickness and the Westervelt equation. Blood samples were taken every 2 weeks at 15:25, before mares were given their allotment of hay cubes on a day when they did not exercise, to measure plasma hormone and glucose concentrations. Gastroscopy for gastric ulcers was performed before, during and after the trial. VO2max increased by 7.0% (P<0.03) in EX, but did not change (P>0.05) in CON. FI decreased (P<0.001) in both groups, but was only different (P<0.02) between EX and CON at week 3. Digestible energy (DE) intake (Mcal day-1) was initially higher (P<0.001) than calculated DE requirements in EX. However, over time, DE only matched and then fell below (P<0.03) the DE intake required for training. In CON horses, DE intake was higher (P<0.001) than calculated requirements. BW and percentage body fat increased (P<0.001) over time in EX and CON. Plasma leptin concentration increased (P<0.001) over time in both groups, but was 60% higher (P<0.04) in CON compared to EX at weeks 4–8. There were no differences (P>0.05) in active ghrelin, glucose, insulin or cortisol between the groups and over time. Five out of seven EX mares developed gastric ulcers. No CON mares developed gastric ulcers. Training was associated with changes in plasma leptin concentration, an increased incidence of gastric ulcers and a disruption of the balance between required DE and actual intake.

The aim of this study was to investigate the effect of feeding frequency on total tract digestibility and plasma glucose, insulin, urea, gastrin and cortisol concentrations at rest and following exercise in seven Standardbred horses in race training. The horses were fed every 12 h (twice a day, 2TD) and every 4 h (six times a day, 6TD) for 25 days, in a cross-over design. The diet (64% grass hay, 36% concentrates on weight basis) was fed at twice the maintenance energy requirement. Blood samples were taken every hour for 24 h on day 17, total collection of urine and faeces was made on days 19–21 and an intensive exercise test was performed on day 25. Altering feeding frequency caused small variations in diurnal plasma glucose, urea, gastrin and cortisol concentrations and did not affect total tract nutrient digestibility. There was an increase in the mean diurnal plasma urea concentration on the 2TD regime and low levels of plasma insulin were observed 7 h after feeding 2TD. The response to intensive exercise on heart rate, plasma lactate and plasma glucose was similar on both treatments but the plasma insulin concentration was higher following exercise in the 2TD regime, indicating that post-exercise glucose metabolism was altered. In conclusion, this study shows that feeding athletic horses only 2TD caused metabolic signs resembling those observed during feed deprivation (low levels of plasma insulin and an increased diurnal plasma urea concentration) and an altered post-exercise glucose metabolism, but did not affect the digestive response.

The objective of the study has been to examine whether the freestyle dressage classes are judged reliably and to elaborate a method assessing the consistency of judging. The data contained 13 000 marks of the ten best-ranked horses at nine Grand Prix classes and four Intermediate I classes from ten international competitions. The marks concerned 119 horses in total and were given by 37 judges. A method for evaluating the consistency of judging has been proposed. The index of disagreement (ID) assesses the disagreement of ranking by an individual judge relative to the general ranking based on the sum of marks awarded by five judges. The results show that the mean ID of individual judges is highly differentiated. The ID is influenced by the judge's position in the arena. The consistency of judging was lower in Intermediate I Freestyle Tests than in Grand Prix Freestyle Tests and it varied in different competitions. The conclusion of the study is that the results of the freestyle dressage classes are often biased. The present system of judging should be permanently checked. The offered method of evaluating agreement between judges' rankings may help to improve the consistency of judging and the reliability of the horses' scores.

Gaited horse research is limited, with the majority of the research focusing on the measurement of the temporal variables of adult-gaited horses. The objective was to measure the fore and hind limb kinematics of the flat-walking Tennessee Walking Horse (TWH) yearling. Four TWH yearlings were filmed at 60 Hz being led at a consistent flat walk that followed breed standards. Reflective markers attached along palpation points of the joint centres of the fore and hind limbs were tracked for five strides for each yearling. During stance, the elbow (154±3°), carpal (185±3°), fore (222±9 and 221±9°) and hind fetlocks (216±11°), hip (111±3°), stifle (157±4°) and tarsal (167±9°) joints demonstrated peak extension with the forelimb fetlock joint having double peaks of extension. During swing, the same joints demonstrated peak flexion with the elbow (109±3°) and hip (88±6°) peak flexion occurring later in the swing phase. The carpal (54±4°) joint demonstrated a greater range of motion than the tarsus (40±9°) with less vertical displacement. The hind fetlock (60±10°) had greater range of joint motion compared with the forelimb fetlock (45±8°), but lacked the double peak of extension during swing. Kinematic measurements will assist in objectively defining the gait for both clinical and performance applications.