God it was ugly - anybody know any better ways of doing this? Long story short, Justus (the palomino pony) is going on stall board for winter and so has to go into the indoor boarder pen. Jessie (the chestnut QH) is head honcho, and aggressively dominant - she will chase even when another horse runs. Justus is also dominant but much more quietly - she never chases, and will simply follow and quietly turn and back up and if the other horse doesn't get the hint, she'll proceed to kick like a demon.
This is only the first minute - this went on for TWENTY minutes. They went at it at LEAST 6-7 times, and we kept breaking it up out of terror someone was going to end up with a broken hock. Justus FINALLY relented, and started trotting away when Jessie backed up to her and Jessie was beat up enough she was happy with that. Thankfully no real injuries, just a lot of bloody scraps and hoof prints. We did this strictly because we KNEW this was going to happen and wanted it done in a controlled atmosphere (hence the leg protection and LOTS of people on hand).
I HATE having to deal with this - anyone else have any tips on dealing with dominant introductions? As a note, they ARE penned beside each other and have been ridden together - they're NOT strangers.