The effects of hypertonic dehydration changes on renal function and arginine vasopressin in the horse during pulling exercises.

This study investigated the effect of hypertonic dehydration on exercise in horses. Valencian draft horses (n=43) with hypertonic dehydration following water and food deprivation and competing in pulling events (COM), were compared to euhydrated horses (n=11) during a pulling exercise test (PET). Both groups were divided into bodyweight (BW) categories A (≤350 kg), B (351-450 kg), and C (≥451 kg), and pulled 2, 2.25, and 2.5 times BW, respectively. Exercise duration (ED) was 1.3±0.8 min. Heart rate, respiratory rate, rectal temperature and blood samples were taken at rest, after exercise, and during the first 30 min of passive recuperation. The only difference between BW categories was the packed cell volume (PCV), which was higher after exercise in COM horses in group A (52.7±2.3%) than in B (49.3±3.4%), so the data for the three BW categories were combined. The COM horses had higher levels of resting plasma proteins, albumin, urea, creatinine, sodium and arginine vasopressin (AVP) than PET horses. Exercise induced significantly greater (P<0.05) increases in heart rate and lactate in the COM horses. AVP was negatively correlated with ED and positively with PCV, plasma proteins, albumin, urea, and sodium. Peak AVP concentrations did not differ in the two groups.

Gender differences in non-specific immune response to exercise in the lactate threshold: a study in equine athletes.

Gender differences have not been shown in relation to the immune system in athletic horses. The aim of the present paper was to elucidate gender differences in the non-specific immune response of the polymorphonuclear neutrophil (PMN), plasma glucose and in hormones before and after an exercise in the lactate threshold (LT). A group of 12 Anglo-Arabian horses (6 females and 6 males, 4-7 years old) was observed. A submaximal exercise test was carried out at the LT. The results showed that males had a higher PMN percentage, plasma glucose values, Adherence index (AI) and random migration than females. Also, females showed significant negative correlations between cortisol and catecholamines with PMN and glucose with phagocytosis, and positive ones between AI and catecholamines. In males, negative correlations were established between random migration and chemotaxis with cortisol, and positive ones between cortisol and phagocytosis.