Instructions
Separate the mare from her friends and handle her on your own. Have a clear understanding of who is dominant. Do not allow her to crowd you.
Watch her closely as you handle her. If she is truly aggressive towards people, she may try to bite or kick. Be ready to reprimand her and demand that she respect your space and your dominance. This may mean you have to take her into a round pen and work her--but do what it takes to gain your position above her.
Take the mare back into an environment with other horses once you have clearly established you are the dominant position. Be prepared for her to regress and try some of her old tricks while you are handling her around her friends and companions. Do not allow her to take her attention off of you and demand that she retain her respect for you.
Keep in mind that mares are unpredictable, and their estrus cycles can make them more so. Once you have identified that a mare is aggressive, always be aware that her behavior can change on a whim. Praise her for her good manners, and correct her instantly in the case of a setback.
Know that aggression in mares is not natural past a certain point. If you see a mare herding other horses like a stallion, or squealing and fighting like a male horse, it is time to consult with a veterinarian. There could well be a hormone imbalance that needs to be addressed.
How to Handle an Aggressive Mare
Horses are herd animals. They depend on a hierarchy to keep order amongst themselves. From the alpha mare to the lowliest member of the herd, order is kept by knowing each animal's place. Aggression in mares is not common, but it is certainly not unusual, as there must always be an alpha mare. Unfortunately, this does not translate well into the domestic situation. This article will give you some tips on how to handle the aggressive mare.