A mare can rupture one of their uterine arteries during the birth of their foal. As an owner, you will not see any blood because it accumulates within the mare’s abdomen. Unfortunately, owners will see the mare becoming restless, acting like they have colic, or just dying. A uterine artery rupture is a serious emergency. Keeping mares with these ruptures quiet and without any stress is important, and never breed the survivors again.