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Article

Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares

1
School of Veterinary Science, The University of Queensland, Gatton, QLD 4343, Australia
2
Samford Valley Veterinary Hospital, Samford, QLD 4520, Australia
*
Author to whom correspondence should be addressed.
Academic Editor: Francois-Rene Bertin
Animals 2021, 11(3), 891; https://doi.org/10.3390/ani11030891
Received: 1 February 2021 / Revised: 17 March 2021 / Accepted: 18 March 2021 / Published: 20 March 2021
(This article belongs to the Special Issue Animal Endocrinology and Medicine Research)
The reproductive cycle of mares is associated with many hormonal changes, but the effects of this cycle and pregnancy on adrenocorticotropic hormone and insulin concentrations are poorly described, which could limit our ability to diagnose pituitary pars intermedia dysfunction and insulin dysregulation. In this study, healthy mares are followed through their reproductive cycle during the physiologic breeding season, and adrenocorticotropic hormone, cortisol, glucose and insulin concentrations are measured to determine the effects of age, pregnancy and the reproductive cycle on analyte concentrations. No significant effect of age, the reproductive cycle or pregnancy is detected on the cortisol, glucose or insulin concentrations; however, adrenocorticotropic hormone concentrations are significantly increased throughout the peri-ovulatory period and during pregnancy. Therefore, knowledge of a mare’s reproductive cycle might be beneficial when interpreting adrenocorticotropic hormone concentrations.
Although there are many hormonal changes associated with reproduction, the effects of ovulation and early pregnancy on adrenocorticotropic hormone (ACTH) and insulin concentrations are poorly described. We hypothesise that both ovulation and early pregnancy will alter ACTH and insulin concentrations in healthy mares. Eighteen mares showing no clinical signs suggestive of, or laboratory findings consistent with, pituitary pars intermedia dysfunction PPID and insulin dysregulation (ID) are enrolled. ACTH, cortisol, insulin and glucose concentrations are measured over their peri-ovulatory period, as determined via ultrasounds and progesterone concentrations. The mares are grouped by age and gestation status, and a two-way repeated-measures ANOVA is used to determine the effects of age and early pregnancy, along with the peri-ovulatory period, on analyte concentrations. No significant effect of age, ovulation or early pregnancy is detected on the mares’ cortisol, insulin or glucose concentrations; however, there is a significant effect of early pregnancy and ovulation on ACTH concentrations (p = 0.04 and p = 0.04 respectively). ACTH concentrations change around ovulation and with early pregnancy. Therefore, knowledge of a mare’s reproductive status might be beneficial when interpreting ACTH concentrations. View Full-Text
Keywords: early pregnancy; endocrinology; equine; hypothalamic–pituitary–adrenal axis; insulin dysregulation; metabolism; oestrous cycle; pituitary pars intermedia dysfunction early pregnancy; endocrinology; equine; hypothalamic–pituitary–adrenal axis; insulin dysregulation; metabolism; oestrous cycle; pituitary pars intermedia dysfunction
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MDPI and ACS Style

Hicks, G.R.; Fraser, N.S.; Bertin, F.-R. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals 2021, 11, 891. https://doi.org/10.3390/ani11030891

AMA Style

Hicks GR, Fraser NS, Bertin F-R. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals. 2021; 11(3):891. https://doi.org/10.3390/ani11030891

Chicago/Turabian Style

Hicks, Gemma R., Natalie S. Fraser, and François-René Bertin. 2021. "Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares" Animals 11, no. 3: 891. https://doi.org/10.3390/ani11030891

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