The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia

The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia

Background Longitudinal evaluation of plasma endogenous ACTH concentration in clinically normal horses has not been investigated in the Southern Hemisphere. Objectives To longitudinally determine monthly upper reference limits for plasma ACTH in 2 disparate Australian geographic locations and to exa...

Full description

Saved in:
Bibliographic Details
Published in:Journal of veterinary internal medicine Vol. 31; no. 5; pp. 1533 - 1540
Main Authors: Secombe, C.J., Tan, R.H.H., Perara, D.I., Byrne, D.P., Watts, S.P., Wearn, J.G.
Format: Journal Article
Language:English
Published: United States John Wiley and Sons Inc 01-09-2017
Subjects:
ACTH
Adrenocorticotropic Hormone - blood
Animals
Australia
EQUID
Female
Horse
Horses - blood
Horses - physiology
Longitudinal Studies
Male
Photoperiod
Prospective Studies
Reference limit
Seasons
ACTH
Reference limit
Photoperiod
Horse
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Background Longitudinal evaluation of plasma endogenous ACTH concentration in clinically normal horses has not been investigated in the Southern Hemisphere. Objectives To longitudinally determine monthly upper reference limits for plasma ACTH in 2 disparate Australian geographic locations and to examine whether location affected the circannual rhythm of endogenous ACTH in the 2 groups of horses over a 12‐month period. Animals Clinically normal horses <20 years of age from 4 properties (institutional herd and client owned animals) in Perth (n = 40) and Townsville (n = 41) were included in the study. Methods A prospective longitudinal descriptive study to determine the upper reference limit and confidence intervals for plasma ACTH in each geographic location using the ASVCP reference interval (RI) guidelines, for individual months and monthly groupings for 12 consecutive months. Results Plasma endogenous ACTH concentrations demonstrated a circannual rhythm. The increase in endogenous ACTH was not confined to the autumnal months but was associated with changes in photoperiod. During the quiescent period, plasma ACTH concentrations were lower, ≤43 pg/mL (upper limit of the 90% confidence interval (CI)) in horses from Perth and ≤67 pg/mL (upper limit of the 90% CI) in horses from Townsville, than at the acrophase, ≤94 pg/mL (upper limit of the 90% CI) in horses from Perth, ≤101 pg/mL (upper limit of the 90% CI) in horses from Townsville. Conclusions and Clinical Importance Circannual rhythms of endogenous ACTH concentrations vary between geographic locations, this could be due to changes in photoperiod or other unknown factors, and upper reference limits should be determined for specific locations.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
This paper was presented at the 2017 Dorothy Russell Havemeyer International Equine Endocrinology Summit in January 2017.
The study was principally supported by a grant from Boehringer Ingelheim with some contribution from the Equine Clinical Sciences Research Fund at JCU.
The work was undertaken in Australia in 2 locations: Perth, Western Australia and Townsville, Queensland.
ISSN:0891-6640
1939-1676
DOI:10.1111/jvim.14782