How to Tell if Your Mare is Pregnant and Why It's Important
you should know at a fairly early stage whether there might be any complications.
Care and Feeding for Pregnant Mares
You would want to determine early on whether your mare is in foal, because her feeding and management may require slight adjustments. You will need to ensure your mare has the best-quality hay or pasture, salt, and minerals.3 If your pasture grass contains fescue, you may want to remove the mare and allow her to graze elsewhere. You may want to separate your mare from any pasture bullies that could cause her harm or injury, and thus make the foaling process more difficult for her.
While it's important to maintain a regular vaccination and deworming schedule throughout the pregnancy, your mare shouldn't receive these medications during the first two to three months. Some vaccines and parasite control medications can interfere with fetal development.4 Your veterinarian is the best resource for advice about which medications are safe to give your pregnant mare throughout her pregnancy.
Yes, it costs money to have your mare properly examined by a veterinarian, but the cost is negligible in comparison to the total cost of raising a foal—or losing a foal or the mare. Breeding a mare is not a cheap way of getting another horse. In fact, raising a foal can be one of the more expensive ways of producing another horse!