This may be true for some, but I disagree for many 'true scramblers'. If you
stop and check a horse that's really scrambling you'll usually find them
worked up into a state, sweat pouring off etc. Personally I don't think it's
'learned' or conscious but more panic from a previous bad experience, or
something that just went screwy upstairs. I've known horses that hauled
beautifully, no bad experiences to precipitate, and then all of a sudden one
day 'click', they start scrambling. It could be balance too. I my
experience once they start - that's it. Quite often it only occurs on one
side - thus if you switch trailer sides they are fine.
Mardi