We had one that did that, too. He also managed to cut an artery in the process. Fortunately, he was sedated for the initial cleaning and debridement of the wound. Daughter had to change the dressing on it every day for a week, then every other day for another three weeks before it healed up enough to leave open. Horse was a real bugger if she tried to change the bandage when I wasn't there. For some reason, our horses tow the line pretty well when I'm standing beside them, but if son in law tries to hold the halter, the horses just knock him out of the way and take off.
Maybe you could have someone hold the halter that your horse behaves around?
Plain Old Dee, horses Dancer and Rain I believe in dragons, unicorns, good men and other mythical creatures!