Horse breeding is a multi-million dollar international industry, and some breeders earn millions in sire rights by breeding award-winning male horses. For purebred horses, careful selection of the male parent (the “sire”) and the female parent (the “dam”) is essential to successful breeding. From conception to foaling, horse breeding today is carefully managed through modern technology. Whether you are breeding horses for racing, competition or the family farm, a firm understanding of the breeding and foaling process will ensure a successful outcome.
Horse Breeding 101
While wild horses typically breed and foal in mid to late spring, domesticated breed for competition requires horses to be foaled as close to January 1st as possible for maximum competitive advantage in the Northern Hemisphere. To help stimulate the ovulation process during winter, keep your mare under barn lights to mimic a longer day. A mare signals that ovulation is occurring by urinating in the presence of a stallion and raising her tail to reveal the vulva.
Once an egg is fertilized, it will remain in the oviduct for 5.5 days before descending into the uterus; fixation will occur on day 16. By day 14, the embryo will be visible on a trans-rectal ultrasound, with a heartbeat detectable by day 23. The placenta will form around day 40 to 45 of pregnancy. The sex can often be determined using ultrasound on day 70. The entire gestation process is approximately 11 months.
Advanced planning will make the foaling process go as easily as possible for both you and your mare. While some mares can handle foaling on their own, it is best for you and your veterinarian to be present in order to offer assistance if needed. While the majority of mares will foal 330 to 340 days from breeding, some may foal as early as 320 days. Mares should be immunized four weeks in advance of foaling with vaccines specifically approved for pregnant mares. These vaccines will stimulate the mare to produce antibodies, which will be passed to the foal in the mare’s colostrum.
Prior to foaling, prepare a foaling stall. Foaling happens quickly once it begins, so closely monitor your mare in the days leading up to the expected foaling date. Wrapping the mare’s tail will make it easier to see underneath the body prior to foaling. Following foaling, a mare will lick the foal to clean it and stimulate circulation. A new foal should be able to stand and get milk from its mother within an hour of birth.