Assessment of the hypothalamic-pituitary-adrenocortical axis function using a vasopressin stimulation test in neonatal foals.
Authors: Elder Erin, Wong David, Johnson Katheryn, Robertson Hannah, Marner Meghan, Dembek Katarzyna
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Vasopressin Stimulation Testing in Neonatal Foals Sepsis remains the leading cause of neonatal foal mortality, with dysfunction of the hypothalamic-pituitary-adrenocortical axis (HPAA) significantly worsening prognosis; this study evaluated whether vasopressin (AVP) stimulation could reliably assess HPAA competence in healthy foals under 72 hours old. Twelve neonates received three escalating AVP doses (2.5, 5, and 7.5 IU) in randomised cross-over fashion between 24–48 hours of age, with cortisol, ACTH, corticotropin-releasing hormone (CRH) and AVP measured at baseline and 15, 30, 60 and 90 minutes post-administration. All three doses elicited significant, dose-dependent increases in ACTH within 15 minutes and cortisol within 30 minutes (P<0.01), whilst endogenous CRH remained unchanged and baseline AVP stayed within normal ranges. For practitioners managing septic foals, this work establishes that a 5 IU AVP bolus is a safe, practical diagnostic tool to identify impaired HPAA function—a finding that could help stratify risk and guide targeted corticosteroid therapy in critically ill neonates where the stress response may be insufficient to sustain survival.
Read the full abstract on PubMed
Practical Takeaways
- •A vasopressin stimulation test using 5 IU dose provides a safe, practical method to assess hypothalamic-pituitary-adrenocortical function in neonatal foals with suspected sepsis
- •The ACTH and cortisol response to AVP can help differentiate HPAA dysfunction in sick foals, which is important since HPAA dysfunction is associated with sepsis mortality
- •This test can be incorporated into diagnostic protocols for critically ill neonatal foals to guide management decisions and prognosis assessment
Key Findings
- •All AVP doses resulted in significant dose-dependent increases in ACTH and cortisol concentrations in neonatal foals
- •ACTH and cortisol were significantly elevated at 15 and 30 minutes respectively after AVP administration compared to baseline (P<0.01)
- •AVP stimulation produced no change in endogenous CRH levels
- •AVP administration at 5 IU is safe and can be used for HPAA assessment in septic neonatal foals