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Journal of veterinary internal medicine2017; 31(5); 1533-1540; doi: 10.1111/jvim.14782

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

Abstract: Longitudinal evaluation of plasma endogenous ACTH concentration in clinically normal horses has not been investigated in the Southern Hemisphere. Objective: 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. Methods: 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: 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.
Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2017-06-29 PubMed ID: 28661009PubMed Central: PMC5598888DOI: 10.1111/jvim.14782Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research examines the effect of geographic location on the annual patterns of ACTH hormone level in horses in two different Australian locations. The study reveals a correlation between ACTH hormone levels and changes in photoperiod.

Research Objective and Methodology

The research aimed at longitudinally establishing the monthly upper reference limits for plasma ACTH, a critical hormone, in horses from different geographic locations in Australia – Perth and Townsville.

  • A total of 81 clinically healthy horses, under 20 years of age, from four different locations were included in the study.
  • Using the American Society of Veterinary Clinical Pathology (ASVCP) reference interval guidelines, the research conducted a descriptive longitudinal study to determine the upper reference limit and confidence intervals for plasma ACTH in each location.
  • The hormonal measurements were taken for individual months and monthly groupings across 12 consecutive months.

Research Findings

The main findings of the study include:

  • Endogenous ACTH concentration in horses demonstrated a circannual rhythm, i.e., it varied in a predictable pattern over a year.
  • The increase in ACTH hormone was not restricted to autumnal months but appeared to be linked with changes in photoperiod (the duration of daily sunlight).
  • ACTH concentrations were lower during the ‘quiescent period’ (the period of minimal change or activity), with levels of ≤43 pg/mL in Perth horses and ≤67 pg/mL in Townsville horses. These levels were significantly lower than the ‘acrophase period’ (the period of peak activity), which recorded ACTH concentration levels of ≤94 pg/mL in Perth horses and ≤101 pg/mL in Townsville horses.

Research Conclusion

The study concludes that:

  • Geographic location influences annual rhythms of ACTH concentration in horses, suggesting this could be due to changes in photoperiod or other yet unexplored factors.
  • Since ACTH concentrations fluctuate in different geographic locations, upper reference limits must be identified for each specific location.

Cite This Article

APA
Secombe CJ, Tan RHH, Perara DI, Byrne DP, Watts SP, Wearn JG. (2017). The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia. J Vet Intern Med, 31(5), 1533-1540. https://doi.org/10.1111/jvim.14782

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 31
Issue: 5
Pages: 1533-1540

Researcher Affiliations

Secombe, C J
  • College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia.
Tan, R H H
  • Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.
Perara, D I
  • College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia.
Byrne, D P
  • College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia.
Watts, S P
  • Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.
Wearn, J G
  • Discipline of Veterinary Clinical Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.

MeSH Terms

  • Adrenocorticotropic Hormone / blood
  • Animals
  • Australia
  • Female
  • Horses / blood
  • Horses / physiology
  • Longitudinal Studies
  • Male
  • Prospective Studies
  • Seasons

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Citations

This article has been cited 16 times.
  1. Humphreys S, Kass PH, Magdesian KG, Goodrich E, Berryhill E. Seasonal variation of endogenous adrenocorticotropic hormone concentrations in healthy non-geriatric donkeys in Northern California. Front Vet Sci 2022;9:981920.
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  4. Horn R, Stewart AJ, Jackson KV, Dryburgh EL, Medina-Torres CE, Bertin FR. Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses. J Vet Intern Med 2021 Jan;35(1):560-570.
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