Is it ever appropriate to induce?

Introduction

The gestational length in horses is extremely variable with reported normal values ranging between 320 and 360 days. Inappropriate timing of an induced parturition can lead to dystocia, premature placental separation, fetal hypoxia, dysmaturity, or stillbirth. Therefore induction of parturition in healthy mares as a routine procedure is not recommended. However, labour has been successfully induced in selected cases of severe maternal illness, and as a routine procedure in clinical research and stud farm management. So is it ever appropriate to induce parturition in the mare?

Data acquisition

PubMed was searched using multiple combinations of the terms ‘induction of parturition’, ‘horse’, and ‘equine pregnancy’. Crossreferencing from studies yielded additional reference.

Criteria for induction of parturition at term

Final fetal maturation only occurs in the last few days prior to parturition, and is crucial for survival and well-being of the newborn foal [1]. The equine fetus does not manifest any physical signs of impeding delivery until the onset of second stage labour when it rotates and moves towards the birth canal [2]. It is therefore necessary to determine fetal maturity based on maternal signs alone [3]. These maternal signs include:
• Appropriate gestational length (>320 days)
• Adequate mammary development
• Presence of colostrum with an appropriate calcium level
• Relaxation of cervix and pelvic ligaments.
[…]