Old maiden mares are considered special mares with the possibility of reduced fertility. An old maiden mare is a mare that is older than eight or nine and has never had a foal. However, there are other mares that are in the same category; mares that are bred at the age of two, foal when they are three, and then go into a show career and are not bred again until they are 12 or older behave very similarly. Not all are the same, but they are all at a higher risk of being a problem.

When our thoroughbred mare Daisy was pregnant with Sham nine years ago, she moved through her stages predictably with no issues. In her last month, her milk bag was slow to fill but the signs of change were there.

During the first eight months of pregnancy, a mare may be fed like any other horse, with a balanced, high quality diet. But things are changing rapidly during the final three months of pregnancy: The mare now requires more calories, more protein, more omega 3s, and balanced vitamins and minerals, not only for the unborn foal but also to prepare for milk production.