Pregnant mares need adequate daily exercise in a paddock or pasture, and any horses kept together should be compatible, which helps to reduce stress. Vaccinations and deworming should be done before the mare is bred, with no vaccinations given during the first 90 days of gestation.

A healthy pregnant horse can be ridden during much of her pregnancy. However, there are periods when riding should be avoided, don’t ride a mare for at least 30 days following conception or during the final two to three months before her due date. Otherwise, it is ok to ride your pregnant horse.

This is often precipitated by the misbelief that 340 or 341 days of pregnancy duration represent a “due date”. Not so! The average duration of gestation is anywhere between 320 and 370 days – so that mare which is at 345 days is not “overdue”, but well within the normal range!

Research shows that transport (9 hours in moderate temperatures) doesn’t increase the miscarriage rate for mares in early pregnancy (16 to 38 days). In late pregnancy, you should complete long-distance transport at least 30 days before the foal is due.

If disturbed, the mare may delay foaling, or worse, may do serious damage to herself or to her foal. Under natural conditions mares most commonly foal in late spring when temperatures are most likely moderate and optimal feed will be available for the post-natal period.

Mares will generally start to ‘bag up’ two weeks prior to foaling, but be warned that this is not fool proof as some mares, especially maidens, may bag up much closer to foaling. Mares may produce a wax like se cretion on their teats up to three days prior to foaling.

The visual signs of a mare’s readiness to foal are:

• Udder distension begins 2-6 weeks prior to foaling.
• Relaxation of the muscles of the croup 7-19 days prior to foaling; relaxation around the tail head, buttocks, and lips of the vulva.
• Teat nipples fill 4-6 days prior to foaling.
• Waxing of the teats 2-4 days before.

Mares generally foal at night. One study, for example, indicated that approximately 80 percent of foals were born between midnight and 6 a.m.

She will lie down more frequently than usual and may roll, as though she has colic. In the last 24 hours, she is likely to produce a loose stool; it is thought that this may be the result of the first uterine contractions. During the first stage of labour, the mare may get up and lie down repeatedly.

Mares are seasonal breeders that cycle from about early May through October. A normal cycle consists of roughly seven days of estrus and a 14-day period of diestrus (when she is not in heat).