An innovative exercise machine, which mimics the movement of horseback riding, has been made available in the market. As an initial step in characterizing this device, we determined the cardiovascular and metabolic responses to exercise. Twenty apparently healthy subjects rode the device (Equus) on day 1. The upper body exercises were added on day 2, to see whether cardiac and metabolic demands were further elevated (Equus+aerobics). After 10 min of continuous exercise, oxygen consumption increased significantly. In the Equus+aerobics condition, increase in oxygen consumption was significant as early as 4 min into the graded exercise test. Overall oxygen consumption was greater in the Equus+aerobics condition than in the Equus condition (P < 0.05). Oxygen consumption returned to baseline levels within 1 h after the Equus (190 ± 58–188 ± 50 ml min− 1) and Equus+aerobics (198 ± 54–194 ± 43 ml min− 1) conditions. Heart rates increased gradually during the graded exercise tests in both conditions (64 ± 11–78 ± 15 and 65 ± 11–83 ± 12 bpm in the Equus and Equus+aerobics conditions, respectively). Both systolic and diastolic blood pressure (BP) increased significantly 6 min into the graded exercise tests and remained elevated throughout exercise in both the conditions. There were no significant differences in BP responses between the two conditions. These results indicate that the cardiac and metabolic stresses achieved with this exercise device are small.

This study was designed to determine the effect of 200 ml of autologous blood instilled in the lungs of healthy horses had on gas exchange, maximal oxygen consumption and breathing mechanics during supramaximal exercise, as a model of exercise-induced pulmonary haemorrhage (EIPH). The subjects were six healthy well-conditioned Thoroughbred horses. On four occasions over a 6-week period, six horses were subjected to two bouts of exercise to fatigue per day, each at speeds equated with an oxygen requirement that was 110% of . Prior to the second bout of exercise on each day, the horses underwent bilateral bronchoscopy during which either nothing (control), or 200 ml of saline, plasma or blood was inoculated into the distal airways, divided equally between each lung. Run time to fatigue, and measurements of pulmonary gas exchange and breathing mechanics were made and analysed for the effects of the four treatments (control, saline, plasma and blood). Inoculation of blood significantly reduced pulmonary oxygen exchange, and run time to fatigue. Plasma inoculation caused intermediate effects, adversely affecting arterial oxygen tension but without significantly reducing or run time to fatigue. Saline treatment had no effect. None of the treatments had an effect on ventilatory mechanics. The results of this study suggest that volumes of blood in the order of 200 ml can impair gas exchange and interfere with the ability of horses to exercise at supramaximal intensities. Blood volumes of this magnitude are readily evident endoscopically, and probably reflect a moderate-to-severe level of EIPH, in contrast to previously published studies where the unilateral instillation of 100 ml of blood or less did not affect performance.

Skeletal injuries in the equine athlete are a tremendous concern with both economic and animal welfare implications. As a result, much research has focused on improving bone quality through nutritional and exercise interventions. With the recent utilization of biochemical markers, changes in bone metabolism can be monitored. This study examined and compared the response of bone markers and estimates of bone mineral content, in studies with nutritional interventions, with those utilizing exercise interventions. The post hoc analyses suggest that nutritional interventions result in less change to bone markers and bone mineral content than exercise treatments. Of the bone markers examined, osteocalcin correlates most strongly to estimates of bone quality while keratin sulphate, an indicator of cartilage turnover, showed the least correlation. Comparing the results of this study with other published studies, similar findings were observed, suggesting that small alterations in exercise play a greater role in affecting measurable changes in bone metabolism and quality of the equine athlete than do small changes in nutrition.

Exercise-induced pulmonary haemorrhage (EIPH) is a major health concern in performance horses, but the presence and severity of this condition in racing greyhounds has received little attention. While equids and greyhounds share many physiological attributes, there are important structural and functional differences that may help protect greyhounds from EIPH. We tested the hypothesis that greyhounds performing a simulated 503 m race would experience EIPH and that the time course of recovery would be similar to the horse, even though the severity or relative extent as indexed by the concentration of red blood cells [RBCs] in bronchoalveolar lavage (BAL) fluid would be lower in comparison with that demonstrated previously in horses. Greyhound dogs (n = 6) raced on two occasions (separated by 7 weeks) and BAL was performed 1 week before, 2 h after and each week for 4 weeks following each race to examine the [RBC], concentration of white blood cells [WBCs], WBC differentials and haemosiderophages in the lungs. Racing increased 10 min post-exercise venous blood [lactate] to 18.6 ± 0.4 mmol l− 1. No epistaxis or pink froth was observed at the nose or mouth of any of the dogs. The [RBC] in the BAL fluid was increased significantly 2 h post-race (baseline = 109.6 ± 11.7 × 103; post-race = 292.3 ± 69.9 × 103 RBC ml− 1 BAL fluid, P < 0.05) and returned to baseline 1 week post-race (149.2 ± 46.2 × 103 RBC ml− 1 BAL fluid, P>0.05 versus baseline). The number of haemosiderophages was not different for any of the measurement periods. The [WBC] in the BAL fluid decreased from baseline and race values at 2, 3 and 4 weeks post-exercise (all P < 0.05). Alveolar neutrophil concentrations were also decreased from baseline and immediate post-race values for 4 weeks post-race. The increased [RBC] in the BAL fluid post-exercise is consistent with the presence of EIPH in these greyhounds. However, the relative extent of EIPH in greyhounds (as indexed by [RBC] in the BAL fluid), as compared with that in the horse, was mild, and the lack of elevation of WBC suggests that, unlike their equine counterparts, inflammatory airway disease was absent.

Some of the clinical signs seen in horses during endurance races may result from increases in neuromuscular excitability and are related to plasma [K+] and [Ca++]. The present study aimed to test the following hypotheses: (1) Potassium supplementation will affect plasma [K+] and may result in clinical signs related to neuromuscular hyperexcitability during an 80 km endurance ride. (2) Plasma [Ca++] will reflect dietary cation–anion balance (DCAB) and calcium intake. Feeding with a high DCAB and high dietary calcium content (1.5% total calcium of daily ration) diets would lead to higher plasma [Ca++] during an endurance race than on feeding high DCAB diets with a moderate dietary calcium content (1% of total calcium of daily ration). The current study was undertaken during the 80 km endurance research ride in 2002 in Virginia, USA. Forty volunteer rider–horse pairs participated in the race. During the race, electrolyte mixtures with (EM+K) and without (EM − K) potassium were supplied to 18 and 22 horses, respectively. After the race, the horses receiving EM − K during the race were supplied with a recovery formula containing potassium (EM-REC). The horses were fed in addition to their own forage (hay and pasture) either their own commercial concentrate (CC; 1% calcium, n = 11) or one of two research-supplied concentrates during 3 months preceding the research ride, one concentrate rich in sugar and starch (SS; 2% calcium, n = 15) and the other rich in fat and fibre (FF; 2% calcium, n = 14). Peripheral blood samples were taken the day before, within 3 min of the arrival at the vet checks at 27, 48 and 80 km, and after 3 h of recovery. Plasma samples were analysed for pH, haematocrit (Hct), [Na+], [K+], [Cl− ], [Ca++], [Mg++], total protein (TP) and albumin [alb]. Effects of sampling times, treatments and interactions were evaluated by ANOVA in a mixed model with repeated measures and applied to the 25 horses that completed 80 km. Eliminated horses had their blood sampled before entering the elimination vet check and 3 h after elimination, and were compared with finishing horses by t-test. As the ride progressed, significant increases were found in plasma pH, [Na+], , [TP], [alb], Hct and osmolality; and decreases in [K+], [Mg++], PCO2, [Ca++] and [Cl− ]. Horses supplied with potassium-free, sodium-rich electrolyte formulae (EM − K) had 12.5% lower (P = 0.001) mean plasma [K+], 7.8% lower (P = 0.024) TP and 8.4% lower (P = 0.004) albumin at 80 km, and at 3 h after the race they had 6.8% lower (P = 0.045) TP, when compared with EM+K supplemented horses. Horses fed with SS and FF had higher [Ca++] at 27 (P = 0.027), 56 (P = 0.006) and 80 km (P = 0.022) when compared with horses fed with CC. The lower [K+] in the EM − K group, and the higher [Ca++] in the SS- and FF-supplemented horses may help prevent increases in neuromuscular excitability and related clinical signs. The lower TP and albumin indicate less dehydration in the EM − K group and could help prevent related disorders.

A kinematic multi-planar analysis (MPA) reduces a subject's three-dimensional motion to two-dimensional projections onto planes defined by a fixed global coordinate system (GCS). An alternative to this kinematic method is a joint coordinate system ( JCS) that describes the three-dimensional orientation of the segments comprising the joint with respect to each other so that the JCS moves dynamically with the horse's anatomy. Therefore, the objectives of this study were to locate where differences may occur between the joint motion measurements made using MPA and those made using JCS and to document why these differences in measurements may occur. A Peruvian Paso was recorded during six walking trials using 60 Hz video camcorders. Skin markers tracked the movements and defined the anatomical axes of antebrachial, metacarpal and proximal phalangeal segments. A JCS was established between the two segments comprising the carpal and fetlock joints to measure flexion/extension, internal/external rotation and adduction/abduction at each joint. The MPA model used two markers aligned on the long axis of each segment and measured flexion/extension angles projected onto the sagittal plane of the coordinate system and adduction/abduction angles projected onto the frontal plane of the coordinate system. Carpal and fetlock flexion/extension angles for the walk were similar for the JCS and MPA (peak absolute difference: carpal joint = 7 ± 4° and fetlock joint = 7 ± 2°), indicating that sagittal plane analysis using MPA is adequate when flexion and extension are the only measurements being made provided the horse's plane of motion is aligned with the plane of calibration. There were relatively larger differences in carpal and fetlock adduction/abduction angles measured using an MPA compared with a JCS. Peak absolute difference between the JCS and MPA adduction/abduction angles occurred at 53% of the stride for the carpus (17 ± 4°) and at 61% of the stride for the fetlock (123 ± 25°). Analysis of the reasons for these differences indicated that the accuracy of frontal plane analysis to measure adduction/abduction is limited by its inability to correct for out-of-plane rotations along the long axis of the segments comprising the joint.