For a mare, the birth of her foal is an explosive process, in the best of circumstances requiring less than a half-hour from the time her water breaks to the time the foal has been delivered through the birth canal. In a wilder existence, a pregnant mare would seek a secluded place to lie down and have her foal, trying to keep safe from predators. A newborn foal is a precocious creature, able to rise to his feet and quickly gaining enough coordination to run close on his mother’s heels.

Yet the first few hours after birth are a critical period for both mare and foal. During this initial couple of hours while the mare and foal are resting and bonding with one another and while the foal is testing his long legs, the mare will undergo the final stage of delivery: Expulsion of the fetal membranes, which include the allantochorion and the amnion.

Some mares hardly notice this process as the fetal membranes slip loose in one quick moment. Other individuals appear mildly colicky, alternately lying down and getting up as uterine contractions create painful spasms. Because there is a high incidence of post-foaling colic in mares, it is critical to determine if her cramping is short-lived and related to uterine contractions or if her discomfort persists due to intestinal colic pain. Colic signs that persist for more than an hour post-foaling are cause for immediate veterinary intervention. The abrupt absence of the space-occupying mass of the foal allows for intestinal displacement, particularly of the large colon, sometimes necessitating surgical correction.

Fetal membranes are usually expelled within 15 to 60 minutes after birth of the foal, but might take two to three hours to pass. If the fetal membranes take longer than four to six hours to be expelled, this is a serious complication known as retained fetal membranes (RFM) that requires immediate veterinary care to avoid colic, laminitis, or infection