How to tell if a Mare is in Season

Mares are known to have “seasonal” cycles. These estrous cycles usually appear early in the spring and are gone before late fall. In nature, these cycles can be longer because they are in constant contact with stallions who tease and encourage breeding. Most mares that are in the wild spend the majority of their time carrying a foal.

Just like women, each mare is different in terms of how she reacts to coming into heat or “season”. In domestic settings, it’s easy to observe the differences between a mare’s winder personality and her “seasonal” one. During their fertile times, they may be grouchy and temperamental, just like a woman who suffers from prementsrual symptoms or PMS. 

When mares become in season, they will attempt to lure a stallion to them. Urination increases dramatically and many times, they will back up so that their hindquarters are in the direction of the stallion. Mares who are high strung, may pace back and forth repeatedly in their stalls or paddocks. If the pacing doesn’t get the stallions attention, many will attempt to make noises, knickering, snorting and high-pitched neighing are all sounds used to attract the attention of their mate. The more agitated the mare becomes the more active they will be. Tails will be swatted from side to side, and simple pacing can turn into trotting. In some cases, the mare will mimic the actions of the stallion in an attempt to get his attention.

As the mare’s urination increases, her vulva may take on a waxy appearance. Mares will raise their tail and hold it to one side while urinating. Towards the ends of the flow the vulva may flare open several times in an attempt to draw attention. They may stomp to indicate they are willing to be mounted. 

A mare’s heat cycle will last anywhere from 3 days to a week, with the cycle repeating every 21 to 23 days. In controlled environments, mares are fairly regular. They are kept away from stallions until a breeding time is chosen. Mares can become in season even though they are not exposed directly to a stallion. In those instances, the signs of PMS and milder versions of the other indicators may be present. 

The best way to know how a mare is going to act while in season, is observation. Watch her carefully and learn her personality. Take note as to how she responds to other horses, mares, geldings and stallions included. This will help in determining the signs that are unique to her personality.