Induction of parturition in horses – from physiological pathways to clinical applications.
Abstract: Based on the marked variability in physiological equine gestation length, induction of foaling in mares often results in the birth of dysmature foals. Precise prediction of preparedness of the mare for foaling is thus essential. Treatment with glucocorticoids mimics the fetal signal that initiates birth. Repeated daily dexamethasone treatment in late gestation results in birth of mature foals but the time from initiation of treatment to foaling is highly variable and complications such as dystocia have been reported. Contrary to most expectations, treatment of prepartum mares with progestogens does not delay but advances the onset of foaling. Prostaglandin F2α (PGF2α) and its analogues are effective to induce foaling but even in mares ready for parturition, foal health remains to some extent unpredictable. This may be caused by a relatively long interval between PGF2α treatment and birth, exposing the fetus for several hours to uterine contractions. Oxytocin reliably induces foaling towards the end of pregnancy, but when given at high doses is effective also in the pre-viable period of gestation, resulting in birth of premature foals. Recent research has focused on reducing the amount of oxytocin with the aim to induce foaling only in mares prepared for foaling. Mares selected on clinical criteria receive 1 dose of 2.5 to 3.5 IU of oxytocin. Mares not responding to oxytocin are judged not yet ready for foaling and treatment is repeated the earliest after 24 h. This protocol at present is the most reliable and safest way to induce parturition in mares.
Copyright © 2021. Published by Elsevier Inc.
Publication Date: 2021-08-15 PubMed ID: 34517269DOI: 10.1016/j.domaniend.2021.106670Google Scholar: Lookup
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Summary
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The research article discusses the methodologies and complications related to inducing parturition (labor) in horses. It explores various hormonal treatments and their impact on the pregnancy, with a particular focus on ensuring the birth of mature foals.
Overview of the Paper
- The article begins by stating the known variability in equine gestation length and the resulting possibility of birthing dysmature (underdeveloped) foals if labor is induced.
- Therefore, the authors stress the importance of predicting when a mare is ready to give birth.
Methods Explored for Inducing Parturition
- One of the methods discussed is the use of glucocorticoids, which imitate the fetal signals initiating birth. They found that repeated daily dexamethasone treatment during late gestation results in mature foals, but timing and potential for complications, such as difficult labor (dystocia), are variable.
- The use of progestogens was found to accelerate rather than delay the onset of foaling, contrary to previous assumptions.
- Prostaglandin F (PGF) and its analogues can induce foaling effectively. However, even in mares ready for parturition, the health of the foal is uncertain due to a potentially long gap between the onset of labor contractions and the actual birth, caused by the PGF treatment.
- Oxytocin is another hormonal method explored, effectively inducing foaling near the end of pregnancy. But if given in high doses earlier in pregnancy, it can lead to the birth of premature foals.
Recent Research and Recommendations
- Existing research is now focusing on reducing oxytocin dosage to induce labor only when the mares are ready. This involves administering a single dose of oxytocin and seeing if the mare responds.
- Mares who do not respond to the treatment are considered unprepared for labor, and treatment is repeated after a minimum of 24 hours.
- At this point, this protocol is deemed most reliable and safest for inducing parturition in mares.
Cite This Article
APA
Nagel C, Aurich C.
(2021).
Induction of parturition in horses – from physiological pathways to clinical applications.
Domest Anim Endocrinol, 78, 106670.
https://doi.org/10.1016/j.domaniend.2021.106670 Publication
Researcher Affiliations
- Graf Lehndorff Institute for Equine Science, Vetmeduni Vienna, Hauptgestüt, 1016845 Neustadt(Dosse), Germany. Electronic address: christina.nagel@vetmeduni.ac.at.
- Department for Small Animals and Horses, Artificial Insemination and Embryo Transfer, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
MeSH Terms
- Animals
- Dystocia / veterinary
- Female
- Horse Diseases
- Horses
- Oxytocin / pharmacology
- Parturition
- Pregnancy
- Progestins
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