Cherry,

Why does my horse bite in a assertive way when she is in her stall and people pass her ?

Dear Unknown Person,

You don't give me much detail about your horse and his care, so I'm also answering this for other people that have horses with a similar problem.

A horse that reaches out to bite horses or people that pass by their stall is usually "saying" two things:

1. I am bored in this confined space.

2. Stay away from this space, it is mine.

Now as to #1, horses are inherently nomadic, that means they have evolved over millions of years to be roamers, constantly on the move in search of food and water and while doing so, gaining regular, constant low-level exercise. Their diet consisted of prairie grass. A stalled horse has had his world turned upside down. He now gets all his feed delivered to him, often consisting of rich feeds such as grain and alfalfa. And he rarely gets out of the stall. When he is taken out, it is often to be ridden for a short period of time (one hour) several times a week. So it is no wonder many stalled horses are jumping out of their skins with boredom and invent games to amuse themselves and pass the time. So the first time a horse that lunges out at passersby gets a reaction (shrinking, ducking, dodging), he has learned that this is a fun interactive game. And he will continue because it gives him something to do.

As to #2, since the stall is where a horse is fed, it is his private guarded space and he could be acting out his pecking order by saying "Stay away from my food and the area where I eat." Horses aren't generally territorial like dogs are except when it comes to feed.

So, bottom line. If a horse is biting out at people and horses, that horse needs more exercise and interaction and probably less rich feed. The more naturally a horse is kept, the less apt he is to exhibit stall vices.