Instructions
Observe the size of your mare's udder. It will increase in size and swell or "bag up" toward the end of the gestation period. Bagging up occurs as early as six weeks for maidens or first-time mothers, while for mature mares it may occur just a few days prior to the birth.
Examine your mare's teats for milk drippings. The occasional dripping of clear fluid from her nipples will turn from white to waxy yellow-grey. This is the colostrum or first milk, and a sure indicator that the mare will go into labor within a few hours.
Check the mare's rump around the tailhead muscles. If both sides of the tailhead look soft and sagging, it means that your mare is preparing to give birth. The sagging occurs as a result of the pelvic area stretching to accommodate the foal through the birth canal.
Look at the mare's vulva. A swollen, slightly open and elongated vulva is a sign that the mare is preparing to give birth.
Observe your mare's body language. It may get stressed, act nervous, be less affectionate than normal and separate itself from other horses as it begins to go into labor.
How to Determine When a Horse Will Give Birth
The gestation period for horses is approximately 11 months, a much longer time than it is for humans. Mares prefer to give birth undisturbed in solitude, generally foaling in the late hours of night or early morning. Even as you anticipate the birth of the foal with excitement, you should gear yourself to monitor your mare while it gives birth, and prepare yourself for any emergency that may arise. A mare will undergo several physical changes as the time for it to foal approaches. Closely observing your mare will help you determine when the time for it to give birth is at hand.