* Head raising: Mares in heat will often raise their heads and necks when approached by a stallion or another mare. This is a sign of submission.
* Flared nostrils: Mares in heat will often have flared nostrils. This is a sign of increased respiratory rate.
* Swelling of the vulva: The vulva of a mare in heat will swell and become red and moist. This is a sign that she is ready to mate.
* Discharge from the vulva: Mares in heat will often discharge a clear or milky fluid from the vulva. This is a sign that she is ovulating.
* Increased urination: Mares in heat may urinate more frequently than usual. This is a sign of increased fluid retention.
* Mounting behavior: Mares in heat may mount other horses, regardless of their sex. This is a sign of sexual desire.
* Aggression: Mares in heat may become aggressive towards other horses, especially stallions. This is a sign of territorial behavior.
If you notice any of these symptoms in your mare, it is important to keep her away from stallions until she is no longer in heat.