Humans undergoing intense exercise exhibit transient microalbuminuria. Previous studies have shown that swimming, but not running, induces microalbuminuria in dogs. In this study, urine samples were collected from nineteen well-conditioned Alaskan sled dogs and analysed by the Heska ERD-Screen Test for microalbuminuria. None of the dogs has microalbuminuria, indicated that well-trained dogs do not develop microalbuminuria after running. Further studies are needed to determine if these dogs do develop microalbuminuria after competition or longer-distane runs.

The purpose of the present study was to determine the influence of fitness on cardiac function, particularly on left ventricular function parameters. Fifteen healthy ‘three-day event’ warmblood horses were examined at rest and immediately after high-speed treadmill exercise (3% incline, 3 min 1.8 m s−1, 3 min 4 m s−1, 3 min 5 m s−1, 3 min 6 and 3 min 7 m s−1, 1.5 min 8 m s−1). Horses were divided into two groups. Group 1 consisted of nine conditioned horses and group 2 included six unconditioned horses. Left ventricular dimensions and function were acquired using standardized echocardiographic indices. To assess the level of fitness, heart rate and blood lactate concentration were determined at rest and immediately after exercise. The group of conditioned horses showed a significantly lower blood lactate concentration (mean value 2.39 mmol l−1) after high-speed treadmill exercise than did the group of unconditioned horses (mean value 3.81 mmol l−1), which clearly revealed the difference in fitness between the two groups. During exercise the heart rate was not significantly different between both groups. Only in the recovery phase did the trained horses show a significant faster decrease in heart rate than did the untrained horses. Mean heart rate during echocardiography immediately after exercise (within the first 2 min) was 105 bpm in the group of trained horses and 113 bpm in the group of untrained horses.Within each group of horses, several echocardiographic parameters differed significantly between resting values and values after treadmill exercise. Particularly, in the group of trained horses, 17 out of 30 echocardiographic parameters (most diastolic) differed significantly between rest and exercise. In the group of untrained horses, only six out of 30 parameters were significantly different. At rest, left ventricular diameter at the apex cordis, left ventricular free wall at papillary muscle level, left ventricular volume and stroke volume, as well as fractional shortening (at the apex cordis and at papillary muscle level) were significantly different between both groups. After treadmill exercise comparison of echocardiographic parameters of the conditioned to those of the unconditioned animals showed no significant differences. In the present study, data have been provided for stress echocardiography in conditioned and unconditioned warmblood horses without any disorders of the cardiovascular system.

Back dysfunction is an important reason for impaired performance in sport horses. Limb movements influence the movements of the back and factors affecting the limbs may therefore affect the movement of the back. The aim of the study was to investigate the influence of weighted boots on the fore- and hind limbs on the movement of the back. The back kinematics of eight horses was studied at the walk and trot on a treadmill. The ranges of movement (ROM) of the back were compared intra-individually, using Wilcoxon matched pairs test, when the horses moved with and without weighted boots on the fore- and hind limbs, respectively. Differences were considered significant at P<0.05. Weighted boots on the hind limbs increased the ROM for dorsoventral flexion and extension in the lumbar back at the walk and decreased the ROM for lateral bending at the thoracolumbar junction at the trot. Weighted boots on the forelimbs decreased the ROM for lateral bending at the withers at the trot. Knowledge of the effect of weighted boots on the back movement is useful in training and rehabilitation of sport horses. Weighted boots on the hind limbs at the walk may induce strengthening of the flexors of the lumbar back and increase the flexion–extension of the lumbar back under controlled conditions.

Chromium (Cr) is required for insulin function in the control of cellular glucose uptake. Other functions of Cr relate to its effects on growth, lipid metabolism, immune responses and interactions with nucleic acids. This study was conducted to obtain information on the effect of Cr supplementation on the metabolic responses of five exercising Standardbred horses. During the experiment, horses were fed every day for a 21-day period in a randomized order either a yeast product without Cr (control) or with 4.15 or 8.3 mg Cr day−1. Horses were exercised on a treadmill, alternating a work day of low-speed exercise at 5 m s−1 on a 3% incline for 45 min with a rest day. Each horse was adapted over a 21-day period to his or her respective supplementation before undergoing a standardized exercise test (SET). The SET comprised five incremental steps, each of 4 min duration, on a treadmill with a 3% incline; the first step was at 5 m s−1 and was followed with increments of 1 m s−1. Blood samples were taken for lactate, plasma glucose, serum insulin and cortisol estimation before, during and after each SET (30, 120 min and 24 h post-exercise). Blood Cr was estimated 2 h after feeding the control or Cr-enriched yeast (intake 8.3 mg Cr) in two horses. Heart rate was monitored throughout each SET. Blood lactate and plasma glucose peaks were highest at 8 and 9 m s−1 during the SET when 8.3 mg Cr was supplied. Serum insulin levels declined during the SET and there were no treatment-related changes. Twenty-four hours after exercise, plasma glucose and serum cortisol concentrations returned to basal levels or lower. Serum insulin rebounded 30 min after exercise but 24 h later, serum insulin concentrations were below resting levels. During the recovery period, Cr supplementation did not clearly affect metabolic responses. These results suggest that Cr supplementation had no beneficial effect in healthy, exercising horses.

Measurement and interpretation of acid–base status are important in clinical practice and among racing jurisdictions to determine if horses have been administered alkalinizing substances for the purpose of enhancing performance. The present study used the physicochemical approach to characterize the daily variation in plasma electrolytes and acid–base state that occurs in horses in the absence of feeding and exercise. Jugular venous blood was sampled every 1–2 h from two groups (n=4 and n=5) of Standardbred horses over a 25 h period where food and exercise were withheld. One group of horses was studied in October and one in December. The time course and magnitude of circadian responses differed between the two groups, suggesting that subtle differences in environment may manifest in acid–base status. Significant daily variation occurred in plasma weak acid concentration ([Atot]) and strong ion difference ([SID]), [Cl−], [K+], [Na+] and [lactate−], which contributed to significant changes in [H+] and TCO2. The night-time period was associated with a mild acidosis, marked by increases in plasma [H+] and decreases in TCO2, compared with the morning hours. The night-time acidosis resulted from an increased plasma [Atot] due to an increased plasma protein concentration ([PP]), and a decreased [SID] due to increases in [Cl−] and decreases in [Na+]. An increased plasma [K+] during the night-time had a mild alkalotic effect. There were no differences in pCO2. It was concluded that many equine plasma electrolyte and acid–base parameters exhibit fluctuations in the absence of feeding and exercise, and it is likely that some of these changes are due to daily variation.

This study used a randomized crossover design, with investigators blind to the treatment given, to test the hypothesis that seven commercially available electrolyte supplements would alter plasma concentrations of Na+, K+, Cl−, lactate, total protein (TP) and total carbon dioxide (tCO2) as well as plasma strong ion difference (SID) and haematocrit (HCT). Ten unfit Standardbred mares (∼450 kg, 4–9 years) completed a series of simulated race exercise tests (SRT) during which venous blood was collected at five sampling intervals (prior to receiving electrolyte treatment, prior to the SRT, immediately following exercise and at 60 and 90 min post-SRT). Plasma electrolyte and tCO2 concentrations were measured in duplicate using a Beckman EL-ISE electrolyte analyser. No difference (P>0.05) between treatments was detected at any of the five sampling intervals for plasma [Na+], [K+], [Cl−] or [tCO2]. Similarly, no significant difference was detected between treatments across each of the five sampling intervals for plasma SID, HCT or TP concentration. There were differences (P<0.05) in plasma [Na+], [K+] and [tCO2] (as well as plasma SID, HCT, and TP concentration) in the immediately post-SRT samples that were attributable to the physiological pressures associated with acute exercise. No differences (P>0.05) were detected between treatments across the pre-electrolyte and pre-SRT sampling intervals for plasma lactate concentration. There was, however, a significant time by treatment interaction during the 0, 60 and 90 min post-SRT sampling intervals for this parameter. The electrolyte supplements featured in this investigation did not affect either plasma tCO2 concentration or SID; however, this result does not rule out the potential for other supplements, especially those containing alkalinizing ingredients, to exert an effect that could push a horse towards threshold values.

The role of cardiac function or dysfunction in the pathogenesis of exercise-induced pulmonary hypertension and haemorrhage in horses has been minimally investigated. We hypothesize that pericardiotomy would enhance diastolic function and attenuate pulmonary vascular pressures in maximally exercising horses. Our objective was to evaluate diastolic function and cardiopulmonary pressures before and after pericardiotomy, at rest and at maximal exercise. Study design was both self- and externally controlled. Five horses underwent pericardiotomy after a baseline exercise test. They subsequently performed the same exercise protocol at 1 week and 13 weeks post-operatively. An external, unoperated control group of five horses performed the same experimental protocol. Pulmonary arterial pressure (PAP), pulmonary artery wedge pressure (PWP), right ventricular pressure, heart rate (HR) and oesophageal pressure were measured continuously at rest and at maximal exercise; maximum rates of ventricular pressure decrease (−dP/dtmax), relaxation half-time (t1/2), time constant of isovolumic relaxation (τ) and pulmonary capillary pressures (PcapP) were derived. Statistical analysis was performed using two-tailed Wilcoxon's signed-rank and rank-sum tests, with significance set at P<0.05. No significant differences were found in any variable after pericardiotomy was performed or between the experimental and external control groups. We conclude that during a 13-week study period, pericardiotomy does not alter pulmonary or ventricular pressures or rate of ventricular relaxation in the resting or maximally exercising horse. Results indicate that, in past and future studies requiring an open pericardium in normal horses, the cardiopulmonary parameters measured here are not affected by reduced pericardial pressure.