A mares gestation is 11 months long (340 days). Most breeders bring their mares in at 310 days and keep a close watch on them because it isn't unusual for your mare to foal at 320 days. Your mare will need a seperate "stall" "shelter" area to foal in where she can be locked into at night (alone).
Remember mares are very sneaky about their foaling. If you have purchased a broodmare from another breeder it is important you gather her full breeding / foaling history. The best approach to foaling is an integrated one-- using as many methods of testing and surveillance as you can muster.
Signs to look for:
Watch for a bag filling with milk. We have Maybe Baby milk test strips (we milk them once or twice a day just for a drop of milk to put on the pH strip. Depending on how she tests is relative to how soon she will foal, theoretically. Ie: if she tests 6.2 pH she will foal in a matter of hours. If her milk tests 6.8pH, she could foal within a 72 hour window. We have found this method to be pretty accurate although those mares sneak one out on you if they can!
Watch for her tailhead turning into jelly. Her tail will be loosey goosey and the flesh around her butt will be like jello prior to foaling.
You will get to be familiar with how she 'carries' her foal. It will be up in the rib cage and her overall shape will be round. When she gets close to foaling, the baby will drop" as we say----- her belly will hang down lower towards her bum, and her profile will seem more pear-shaped. This is the baby positioning itself to be born.
Foals are born the same as calves. Front feet first, then you'll see the nose, then the head, then the rest of baby will come . Baby foal has to literally "dive" out of the womb.
From the time the mare gets down on the ground and starts to PUSH, that baby has 15 minutes to get out of there. If she is pushing, you don't see feet and you hit the 15 minute mark, phone the vet. Chances are everything is fine. But if you have issues contacting a vet and he takes half an hour to come out to your place, time is valuable (just in case there is an issue). Better off to be a ready Freddy.
If you see the front feet are upside down , or it's coming butt first, or any other malpresentations, breathe, and don't panic. Phone the vet and then go ahead and put some plastic gloves on and feel around to see whats going on. Sometimes the a front leg may be bent at the knee, etc and it's easy to move it around. Time is of the essence.
When foal is born, make sure there is no sack over its face that might suffocate it. Otherwise, leave it alone-- it will break the cord itself when Momma gets up.
Its incredibly important baby gets it's first colostrum. Mom and I always stay up to watch the foal drink its first meal. Some foals are BOOM figure it out right away, and other foals are stupid and fumble around for a few hours.. but we haven't had problems yet.
Keep an eye on baby for its first few weeks. They go downhill fast so you need to act quick if somethings wrong. diarrhea is always a bad sign and call the vet. If the foal just looks sad and not well, it could be as simple as low blood sugar, and all the vet needs to administer is a little glucose. Its not always catastrophic :)
Red bag delivery: Learn more about it here: http://iamranch.com/miniredbag.htm
Dummy foals. Learn more about it here: http://www.thehorse.com/articles/26863/dummy-foal-syndrome-equine-neonatal-maladjustment-syndrome
Foaling - http://www.williminiatures.com/gestation-and-foaling-a-miniature-mare.php
Les Roy - Canadian Distributor of Maybe Baby Test Strips - firstname.lastname@example.org