Thanks Minimor, but this didn't happen in the pasture. Everyone gets along pretty well outside. If someone gets grouchy, there is room to get away. This was at evening feeding time. I was bringing everyone inside for the night. Each has his or her own assigned stall. I just open the barn door and everyone knows where to go. I then go along behind and close the stall door. This night, for some reason, Susie decided she wanted Gayla's stall. Gayla was standing peacefully in it waiting for me to close her door. Before I could get to her and close the door, Susie charged in and proceeded to reek havoc. Gayla may be the biggest horse on the place, but she's at the bottom of the pecking order.
If I could have gotten my hands on a whip I swear I'd have beaten Susie to death. Luckily for her there was no whips handy. Or guns. I'm trying to be whip free around here. I don't want to be beat on and I sure don't want my horses beat, but this tested the mettle of the nicest person.
After it was all over with and Gayla had torn herself up jumping through the feed door, Susie settled right down and let me lead her to her stall. She has been just fine ever since.
Thankfully, I've settled down too and don't know any horse traders. Or Susie would have been gone by now.