Synthetic adrenocorticotropic hormone stimulation tests in healthy neonatal foals.

This research article explores the impact of different doses of cosyntropin, a synthetic adrenocorticotropic hormone (ACTH), on the adrenal function of healthy neonatal foals, with the discovery that 10- and 100-microgram doses of cosyntropin are suitable for such evaluations.

Objective and Methods

• The researchers started with an objective to evaluate whether peak serum cortisol concentrations in healthy foals will alter significantly after administrating varied quantities of cosyntropin intravenously.
• The experiment involved 14 healthy neonatal foals aged 3-4 days, and a randomized cross-over model was utilized for the study.
• Different doses of cosyntropin (1, 10, 100, or 250 micrograms) were administered intravenously on the 3rd and 4th day of their life.
• Blood samples were collected before and in diverse intervals (30, 60, 90, 120, and 150 minutes) after administering cosyntropin for determining the serum cortisol concentration.

Results and Analysis

• The results indicated no significant increase in serum cortisol concentrations after the administration of 1 microgram of cosyntropin.
• Cortisol concentration recorded a peak 30 minutes after the administration of 10 micrograms of cosyntropin, and after 90 minutes for 100 and 250 micrograms of cosyntropin.
• The research deduced no specific relationship between the cosyntropin dose and serum cortisol concentration at the 30-minute interval.
• It was found that compared to the 10-microgram dose, 100 and 250 micrograms of cosyntropin induced significantly greater cortisol concentrations at the 90-minute mark. Notably, at this point, the 10-microgram dose became indistinguishable from the baseline.
• The area under the cortisol concentration curve between the 100- and 250-microgram doses showed no significant difference.
• The study also found no effect of the day of testing or foal weight on the peak cortisol concentration.

Conclusions and Recommendations

• Based on the results, the study concluded that 10- and 100-microgram doses of cosyntropin would be suitable for evaluating adrenal function in neonatal foals.