Urogenital Normal
The reproductive tract of a mare includes two ovaries and a two-horned uterus. Mares reach sexual maturity and begin heat cycles around 12 months of age. The heat cycle in horses is seasonal, ranging from April through October. The estrous cycle varies in length with the average being 21 days. The mare is receptive to breeding during the estrus period, which lasts 5-7 days. With successful breeding, the gestation length of the horse varies from 11-12 months.