Renin, aldosterone and cortisol in the thoroughbred horse.

This study investigated the activity levels of renin, aldosterone, and cortisol in thoroughbred horses. The findings suggest that these horses have a functional renin-aldosterone system, albeit with a lower renin activity compared to other mammals.

Introduction

• The research aimed to study the activity of certain hormones in the renin-aldosterone system, a crucial regulatory system in mammals, in thoroughbred horses. Renin, aldosterone, and cortisol all play significant roles within the cardiovascular and adrenal systems of animals.

Methods

• The hormones were examined through the measurement of simultaneous morning activities, facilitated by the collection of blood samples from 25 horses.
• Both the concentrations of aldosterone and cortisol, as well as the activity of plasma renin, were measured in these samples.

Results

• Results indicated that the level of renin in all horses was relatively low, with an average of 0.16 ng Angiotensin I/ml per hour. Similar observations were made for the levels of aldosterone and cortisol in plasma, which were around 527 pmol/l and 141 nmol/l respectively.
• Through statistical analysis, a significant positive correlation was found between levels of aldosterone and levels of renin across all horses. However, cortisol levels showed no correlation with either renin or aldosterone.
• Additionally, among male horses, there was a notable negative correlation between the age of the horse and renin levels, suggesting renin levels decrease as horses age.

Conclusion

• The findings of this study suggest that the thoroughbred horse has a functioning renin-aldosterone system. This system, however, is characterized by considerably lower levels of plasma renin activity when compared to other mammalian species.
• This information could be essential in furthering our understanding of the physiological characteristics of horses and potentially improve their care, keeping them in optimal health.