Equine Internal Medicine Resident The Ohio State University / Hagyard Equine Medical Institute Lexington, Kentucky, United States
Abstract:
Background: Sepsis remains the leading cause of death in foals. Hypothalamic-pituitary-adrenal gland axis (HPAA) dysfunction, a common complication of sepsis, is associated with decreased survival and can be diagnosed with a vasopressin (AVP) stimulation test. Hypotheses/
Objectives: Administration of exogenous AVP will increase systemic ACTH and cortisol concentrations in foals, and this response will be attenuated in critically ill compared to healthy foals. Animals: 14 healthy and 43 hospitalized foals: 19 septic (sepsis score>12), 24 sick non-septic (SNS; not critically ill)
Methods: A prospective, randomized repeated measures design was utilized to assess HPAA function and compare ACTH and cortisol concentrations at 0-, 15-, 30-, 60-, and 90- minutes following administration of 5 IU of AVP in healthy, SNS, and septic foals.
Results: ACTH and cortisol concentrations increased at 15 and 30 minutes in all groups compared to baseline (P< 0.01). ACTH concentration was lower in septic (150±96 pg/ml) and SNS (110±88 pg/mL) compared to healthy foals (214±127 pg/ml) 15 minutes after AVP administration (P< 0.05). Healthy foals had lower cortisol concentrations at 0-, 15-, 60-, and 90-minutes compared to septic foals (P< 0.05). Fold increase in ACTH was lower in septic (3.9±3.3) compared to SNS (4.6±3.2) and healthy foals (7.9±3.3) (P< 0.01). There was no difference in fold increase of cortisol between groups (P>0.05). Conclusion and Clinical Importance: An IV AVP stimulation test can be used to evaluate the HPAA in critically ill foals. ACTH response to AVP appears to be a more sensitive indicator of HPAA dysfunction in ill foals than cortisol response.
