Before attempting to breed your mare, you must get her in good physical condition. Underweight and unhealthy mares do not cycle well. To get a mare to cycle early in the year, she should be exposed to light 16 hours a day. The extended day length should begin 8 to 10 weeks before the anticipated breeding date. Once the mare begins cycling, the dates of her heat period should be carefully recorded and that information is used to help determine when the mare is ready to be bred. Mares that are foaling do not need lights as they will usually come into heat after foaling and cycle regularly.

When the mare is in heat, a veterinarian examines the reproductive tract and determines if there is significant follicular activity and if the uterus is healthy. Any abnormal conditions are treated at this time.