How long are mares in season and how many times a year do they go into season? How can you tell when the mare is in season?

Horses January 19, 2010 Print Friendly and PDF
The horse is a seasonal breeder, also termed "long day" breeder. This means they only go into estrus during the summer months (or long days). The natural breeding season is late April to October. Cycle length is about 21 days in duration, with diestrus (not in heat) lasting an average of 14 to 16 days, estrus (in heat) lasting an average of four to eight days, and ovulation occurring one to two days before the end of estrus. You can tell a mare is in heat or estrus by seeing if she is receptive to a stallion, flexes her pelvis, raises her tail, urinates frequently, winks the lips of her vulva, and will seek out a stallion, or sometimes even a gelding.