Preliminary investigations into factors that affect plasma aldosterone concentrations in horses.

This research investigates the effects of varying sodium diets and exercise on the concentration of plasma aldosterone in horses and ponies and offers validation for the use of human immunoassay kits to measure these concentrations.

Objective of the Research

• The main objective of this research was to understand how different sodium diets (low, adequate, high) and moderate to high-intensity exercise impact plasma aldosterone concentrations in horses and ponies. Another aim was to confirm the effectiveness and repeatability of human immunoassay kits in measuring aldosterone levels in these animals.

Findings on Sodium Diets and Aldosterone Concentrations

• When horses were on a diet with sufficient sodium, plasma aldosterone concentrations peaked around four hours after feeding. There wasn’t much fluctuation in aldosterone levels before feeding over three consecutive days.
• Adding extra salt to the diet initially didn’t increase plasma aldosterone in three of the four animals. However, after five days, all animals showed lower pre-feeding concentrations, an increased reaction to feeding, but a reduced absolute concentration increase.
• Feeding a diet with decreased sodium content for several months didn’t result in consistent changes in pre-feeding aldosterone concentrations. But, there were times when all three animals exhibited increased aldosterone responses to feeding.
• There was no correlation found between changes in fractional electrolyte excretion values and alterations in aldosterone response.

Impact of Exercise on Aldosterone Concentrations

• Exercise resulted in a noticeable increase in aldosterone concentrations in the tested horses. This conforms to the expected biological response to physical activity.

Validation of Human Immunoassay Kits

• Human immunoassay kits used to measure aldosterone levels in horses and ponies were also evaluated as part of this study. The kits showed acceptable levels of reproducibility and repeatability in measuring aldosterone concentrations, and the values obtained from these kits corresponded closely, indicating a high level of reliability.