Baseline plasma cortisol and ACTH concentrations and response to low-dose ACTH stimulation testing in ill foals.
OBJECTIVE
To evaluate baseline plasma cortisol and ACTH concentrations and responses to low-dose ACTH stimulation testing in ill foals.


METHODS
Cross-sectional study.


METHODS
58 ill foals.


METHODS
Baseline cortisol and ACTH concentrations and cortisol concentrations after administration of a low dose of cosyntropin were determined within 6 hours after admission. Foals were assigned to 4 groups on the basis of age (<or=24 hours vs 1 to 56 days) and presence of septicemia (yes vs no). Values were compared among groups and with values previously reported for healthy foals.


RESULTS
Plasma cortisol concentrations 30 and 60 minutes after cosyntropin administration in foals<or=24 hours old were significantly higher than corresponding cortisol concentrations in older foals. In all 4 groups, plasma cortisol concentration 30 minutes after cosyntropin administration was significantly higher than baseline cortisol concentration or concentration 60 minutes after cosyntropin administration. No differences in baseline cortisol or ACTH concentration or in the ACTH-to-cortisol ratio were detected between groups or when ill foals were compared with healthy foals. A small number of ill foals had low baseline cortisol and ACTH concentrations or low responses to cosyntropin administration, compared with healthy foals.


CONCLUSIONS
Results indicated that most ill foals in the present study population had adequate responses to cosyntropin administration. However, a small subset of ill foals appeared to have dysfunction of the hypothalamic-pituitary-adrenal axis.
Wong
David M
DM
Department of Veterinary Clinical Sciences, Iowa State University, Ames, IA 50011, USA.
Vo
Dai Tan
DT
Alcott
Cody J
CJ
Peterson
Anna D
AD
Sponseller
Brett A
BA
Hsu
Walter H
WH
D000302:Adrenal Cortex / Q000502:physiology; D000304:Adrenal Cortex Function Tests / Q000379:methods / Q000662:veterinary*; D000309:Adrenal Insufficiency / Q000175:diagnosis / Q000662:veterinary*; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D019540:Area Under Curve; D003366:Cosyntropin / Q000493:pharmacokinetics*; D003430:Cross-Sectional Studies; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D006854:Hydrocortisone / Q000097:blood*; D008297:Male
D003366:Cosyntropin; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone