Endocrinologic, hematologic, and heart rate changes in swimming horses.

The study examines the short-term changes in heart rate, blood (hematologic), and hormone (endocrinologic) changes in swimming horses. Two sets of experiments involving Standardbred and Thoroughbred horses were conducted a week apart to gain insight into these changes based on the duration of swimming.

Methodology

• Two identical experiments were performed with a gap of one week. The first experiment involved 31 horses (Experiment A) and the second involved 17 horses (Experiment B).
• Horses were categorized into four groups based on their swimming duration: from 1 to 5, greater than 5 to 10, greater than 10 to 15, and greater than 15 minutes.
• The heart rate, PCV (Packed Cell Volume), and plasma concentrations of total proteins, cortisol, triiodothyronine, thyroxine, insulin, and glucose were analyzed – taken before, immediately after, and one-hour after swimming.

Results from Experiment A

• There was a significant effect (“main effect”) of time of sampling on the horse’s PCV, total protein, triiodothyronine, thyroxine, and insulin levels. This indicates that the mentioned parameters changed over the course of time (pre, post, and one-hour after swimming) in Experiment A.
• The duration of swimming had a “main effect” on the insulin concentration, meaning swimming time notably influenced the insulin levels in the horses.
• There was an interaction effect noted between duration of swimming and time of blood collection on heart rate and cortisol concentration. This implies that the heart rate and cortisol levels were influenced by both the duration of swimming and the time of sample collection.

Results from Experiment B

• The time of blood collection had a “main effect” on all variables except for glucose. This indicates that sampling time significantly affected all measured parameters except for glucose levels.

Conclusion

The research concludes that changes in the endocrine system, blood, and heart rate in horses can be significantly influenced by swimming duration and the time of sample collection. These findings suggest that swimming could be a substantial element affecting short-term physiological changes in horses. These effects could, in turn, be used to help tailor training regimens and potentially enhance race performance.