Effects of exercise and EDTA administration on blood ionized calcium and parathyroid hormone in horses.

This research investigates the effects of exercise and the administration of EDTA (a chelating agent) on blood calcium levels and parathyroid hormone amounts in horses. The study determined that both exercise and EDTA caused a reduction in calcium levels and an increase in parathyroid hormone amounts, suggesting that calcium reduction leads to elevated parathyroid hormone production.

Methodology

• The study involved a total of 22 horses. 17 of these horses participated in a show jumping competition while the remaining 5 horses were administered EDTA, a substance known to induce hypocalcemia (low calcium levels in the blood).
• Blood ionized calcium (Ca2+) and plasma parathyroid hormone (PTH) concentrations were measured before and after the jumping competition as exercise-induced alterations. For the horses not participating in the exercise, they were measured during an intravenous administration of EDTA.

Results

• For the horses that exercised, there was a significant decrease in blood calcium concentration accompanied by a significant increase in plasma parathyroid hormone concentration. A correlation was found between blood calcium concentration and plasma hormone concentration, suggesting a possible link between these two factors.
• Administration of EDTA to the group of 5 horses led to hypocalcemia. Hypocalcemia refers to a medical condition characterized by low levels of calcium in the blood. This was accompanied by an increase in PTH concentration, a similar result to those horses who performed exercise.
• The study highlighted that for the same decrease in calcium concentration, the increase in hormone concentration was similar, whether induced by exercise or EDTA administration.

Conclusions

• The results of this study propose that the increase in plasma parathyroid hormone concentration in horses post-exercise occurs due to hypocalcemia. This indicates that the body reacts to reduced calcium levels by producing more parathyroid hormone.
• The increase in PTH concentration was found to be consistent with the decrease in calcium concentration. This suggests a likely equilibrium that the body maintains between these two biochemical parameters. When calcium levels go down, PTH goes up to compensate.