Hmmm...anxious to read some responses to this one.
Personally, I would be very upset with anyone that simply takes it upon themselves to "discipline" my horse. That's rude IMO. I thought when a horse pees it could be out of anxiousness or is relaxed , same as for pooping. That's what T does in the trailer, just "releasing" a bit of anxiety.
Or, is she "expressing" her opinion about trailering? Hmmmm...interesting.