External stress increases sympathoadrenal activity and prolongs the expulsive phase of foaling in pony mares.
Abstract: Mares usually give birth when they perceive their environment as safe and therefore disturbance at foaling may inhibit labor. In this study, foaling mares were transferred to an unfamiliar environment at rupture of the allantochorion (stress, n = 6) or were left undisturbed (control, n = 5). The progress of foaling, heart rate, heart rate variability (HRV) and plasma catecholamine, oxytocin and cortisol concentration were determined. In stressed mares, time from rupture of the allantochorion to appearance of the fetal feet (5.3 ± 1.1 vs. 1.6 ± 0.4 min) and total length of fetal expulsion were longer than in controls (both p < 0.05). Heart rate decreased during the expulsive phase of foaling in control mares (p < 0.01) but increased transiently in stressed mares. Heart rate calculated as percentage of the baseline was higher in stressed than in control mares (p = 0.05). HRV variables SDRR (standard deviation of the beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat differences) increased during foal expulsion (SDRR p < 0.01 and RMSSD p < 0.05). The increase in HRV was delayed in stressed compared to control mares (SDRR and RMSSD time x group p < 0.05). Plasma epinephrine and norepinephrine concentrations calculated as area under the curve for the expulsive phase of foaling were higher in stressed than control mares (p < 0.05). Concentrations of oxytocin and cortisol were elevated during foal expulsion (both p < 0.001) but not different between groups. In conclusion, disturbance of mares during expulsion of the foal prolonged foaling. This effect is most likely mediated via increased sympathetic activity and not inhibition of oxytocin release.
Copyright © 2019 Elsevier Inc. All rights reserved.
Publication Date: 2019-02-04 PubMed ID: 30743099DOI: 10.1016/j.theriogenology.2019.02.006Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
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 study aims to understand the impacts of external stressors on the birth process in horses, identifying that disturbances can inhibit labor and prolong the expulsion phase of a foal, which is likely linked to heightened sympathetic activity.
Study design and methodology
- Two groups of foaling mares were studied – one consisting of mares that were disturbed by being transferred to an unfamiliar environment at the time of the rupture of the allantochorion (stress group, n=6), and the other where the mares were left undisturbed (control group, n=5).
- The researchers monitored the progress of foaling, heart rate, heart rate variability (HRV), and plasma catecholamine, oxytocin and cortisol concentration in both groups.
Key findings
- In the stress group, the time from rupture of the allantochorion to the appearance of the foal’s feet and the total length of fetal expulsion were significantly longer than those in the control group.
- While heart rate decreased during the expulsion phase in the control group, it increased temporarily in the stressed mares, with the percentage of the baseline heart rate being higher in the stress group than in the control group.
- The variables measuring HRV, SDRR (standard deviation of the beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat differences), increased during the expulsion of the foal, but this increase was delayed in the stress group compared to the control group.
- In the stress group, there were higher concentrations of epinephrine and norepinephrine during the expulsion phase.
- While the levels of oxytocin and cortisol rose during foal expulsion, there was no difference detected between the stress and control groups.
Conclusion
- The researchers concluded that disturbing mares during the foal’s expulsion can extend the birth process. This effect is likely caused by increased sympathetic activity rather than an inhibition of oxytocin release.
Cite This Article
APA
Melchert M, Aurich C, Aurich J, Gautier C, Nagel C.
(2019).
External stress increases sympathoadrenal activity and prolongs the expulsive phase of foaling in pony mares.
Theriogenology, 128, 110-115.
https://doi.org/10.1016/j.theriogenology.2019.02.006 Publication
Researcher Affiliations
- Gynecology, Obstetrics and Andrology, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
- Gynecology, Obstetrics and Andrology, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
- Gynecology, Obstetrics and Andrology, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
- Graf Lehndorff Institute, Vetmeduni Vienna, 16845 Neustadt (Dosse), Germany. Electronic address: christina.nagel@vetmeduni.ac.at.
MeSH Terms
- Animals
- Catecholamines / blood
- Chorioallantoic Membrane
- Epinephrine / blood
- Female
- Heart Rate
- Horses / physiology
- Hydrocortisone / blood
- Labor, Induced / veterinary
- Norepinephrine / blood
- Oxytocin / blood
- Parturition
- Pregnancy
- Stress, Physiological
- Time Factors
Citations
This article has been cited 7 times.- Felici M, Sgorbini M, Baragli P, Lanatà A, Marmorini P, Camillo F. Autonomic nervous system balance in parturient mares: Spontaneous vs induced delivery. PLoS One 2023;18(3):e0283116.
- Baqueiro-Espinosa U, McEvoy V, Arnott G. Factors influencing ease of whelping and its relationship with maternal behaviour and puppy perinatal mortality in commercially bred dogs. Sci Rep 2022 Apr 23;12(1):6680.
- Walter MH, Abele H, Plappert CF. The Role of Oxytocin and the Effect of Stress During Childbirth: Neurobiological Basics and Implications for Mother and Child. Front Endocrinol (Lausanne) 2021;12:742236.
- Nagel C, Melchert M, Aurich C, Aurich J. Differences in Endocrine and Cardiac Changes in Mares and Her Fetus before, during, and after Parturition in Horses of Different Size. Animals (Basel) 2020 Sep 4;10(9).
- Allen Wild C, Yon L. Commentary on the Adaptive Significance of Sociality Around Parturition Events, and Conspecific Support of Parturient Females in Some Social Mammals. Animals (Basel) 2024 Dec 13;14(24).
- Thayer ZM, Samsonov A, Farewell CV, Gildner TE. Evolutionary mismatch in emotional support during childbirth: Lessons from the COVID-19 pandemic. Evol Med Public Health 2024;12(1):277-286.
- Malvasi A, Baldini GM, Cicinelli E, Di Naro E, Baldini D, Favilli A, Quellari PT, Sabbatini P, Fioretti B, Malgieri LE, Damiani GR, Dellino M, Trojano G, Tinelli A. Localization of Catecholaminergic Neurofibers in Pregnant Cervix as a Possible Myometrial Pacemaker. Int J Mol Sci 2024 May 22;25(11).
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
