The potential role of training sessions on the temporal and spatial physiological patterns in young Friesian horses

This study compares the circulating adrenocorticotrophin hormone (ACTH), cortisol, lactate, glucose, heart rate, respiratory rate, rectal temperature, and blood count values in initially 2-year-old horses subjected to dressage training schedule during three consecutive days per 2 weeks. Sixteen healthy Friesian horses were used and were considered dressage group. Six healthy young horses not involved in training programs were used as control group. Blood sampling were collected from the jugular vein in baseline condition (dressage group and control group) and after exercise, within 5 minutes of the end of the training session (dressage group). Compared to baseline values, results showed higher ACTH concentrations after the first day of the first training week (P<.005) and after the third day of the second week (P<.005); higher lactate concentrations after the second and the third day of the second week (P<.01); lower glucose concentrations after the third day of the first week (P<.01); higher HR, RR, and RT values and lower PLT count after different time points during both training weeks. One-way ANOVA showed significant training effect for ACTH (F=7.605;P<.0001) and glucose (F=3.505;P<.001) concentrations overtime points. Two-way ANOVA showed a significant effect of dressage training sessions between the first and the second week for ACTH (F=6.508;P<.001) and cortisol (F=5.559;P<.0001) concentrations. From obtained data, it seems that the use of ACTH and cortisol changes for the assessment of effects of training in initially 2-year-old horses could be an ideal measure of quantitative and qualitative stress responses. The quantification at the same time of functional responses to stressful stimuli may offer a more objective measurement of dressage training effects.