Today my pack horse went wild while carrying 1k gold, upon going wild it dropped a blue backpack onto the ground with my 1k gold in it this pack could not be picked up, only emptied i don't remember packy's ever dropping bags like this!
We actually have a bug report open on this also. I have no idea why this is the default method of a pet going wild in RunUO, but it will be fixed. Along with the drop command.