Reproduction Vets


Reproduction- Mares reach puberty at about 18 months of age and undergo an estrous, or heat, cycle. Mares go into heat repeatedly during the breeding season, which usually continues while day length is long and ends when winter approaches. Exposing mares to increasing periods of artificial light can get the breeding season started earlier. During the breeding season, mares ovulate regularly every 3 weeks, but they are in heat and receptive to a stallion for only 2 to 8 days. Heat is generally longer early in the season (spring) and only 2 to 3 days in late June. Gestation (pregnancy) lasts 330 to 342 days, with lighter breeds generally having a longer pregnancy (340 to 342 days) than heavier breeds (330 to 340 days). Pregnant mares generally have a single foal; twins are rare. Foals can see and stand to suckle soon after birth.