I am surprised by how often I am presented with a mare that "should have foaled 2 weeks ago." The owner has been anxiously awaiting the foal. They bring the mare to me "just to be sure that everything is ok." I examine the mare. She is not pregnant, just extremely fat.

In some cases, a mare was put out with a stallion and pregnancy was assumed but never confirmed. In other cases, the pregnancy was confirmed but apparently lost. In either case, the mare was fed to support a pregnancy.

The average mare has a pregnancy (gestation period) of 335 days but normal pregnancies can be 320 to more than 365 days in length. The standard veterinary approach is to confirm pregnancy with ultrasound at 14-16 days past the end of the heat cycle in which she was bred. A recheck ultrasound is typically done at 45-60 days. At this point, for healthy mares, the pregnancy is relatively secure for the duration.

For mares with reproductive problems and especially older mares, the pregnancy may be monitored multiple times before foaling. Mares that have had multiple foals tend to have pendulous bellies and tend to look pregnant even if they are not.

There are countless reasons to properly manage horse breeding versus taking a "wait and see approach". Pregnancy diagnosis and monitoring under the guidance of your vet is simply smart. Have ultrasound examinations performed at the prescribed times, and have your vet monitor the pregnancy as needed.