Originally Posted by Kayty
Can you get someone out there to work with her for a while, getting her comfortable with the halter? Please don't sedate a horse to trailer them... don't know if you've ever seen a horse snap badly out of a sedation, but it's not pretty. They have no sense of pain or where they are, and will do anything to get out of the situation. If the mare snaps out in the trailer, you may well end up with a dead or near dead horse. Of course there are the more common issues about sedation while travelling, affecting balance and digestion which may easily give you a horse that goes down while travelling, or getting colic.
If you're using a transport company to do it, very few of them will allow a sedated horse on board anyway, and most have experienced horsemen on board to load the horse safely. Leave them to do their job without interfering and you'll be fine.
Most I know won't load an un-halterbroke horse either, so make sure your company understands the situation before "counting" on them to do the pick up.
I agree... do NOT sedate her. It's not safe for horses to travel sedated.
Draftrider has about the only option available to you if this mare can't be halterbroke in the time needed.