hmmm we don't float our horses very often at all... but when we have, they haven't gotten sweaty.
How long are your journeys? Perhaps they're too long with out a break? Otherwise, is she worried about traveling and stresses out in the trailer which makes her sweaty?
When I bestride him, I soar, I am a hawk: he trots the air; the earth sings when he touches it; the basest horn of his hoof is more musical than the pipe of Hermes. ~William Shakespeare