Julia, We had a problem with Monte's mare not wanting to back out of a
straight load trailer after always turning around in a stock trailer.
(So, not just an Arab problem.) If your horse is used to being longed &
long lined, bridle horse(have halter on too) attach long lines to bit.
Use halter & lead rope to load horse. Then use long lines & ask horse to
back out. Be patient & slow. Start this when you're not in a hurry. It is
absolute that your horse must understand the "Back" command outside the
trailering situation. The long lines (you are outside the trailer)
allows you to let the horse turn head a litttle to look back without turning
completely around. A slant load takes a little longer sometimes for the horse
to get the idea of turning a little as they back. I use a verbal command (such
as "Step Down") when the next step is to the ground. After a while they make
the connection & it makes it simpler if you have to use a strange trailer. The
important thing is go slow & build trust.Nancy.