That poor pony No wonder she is traumatised!! I hope the dog owner is taken to task over this matter and is forced to pay the vet bill (at the very least!!).
I have to say the only American bulldog I ever met was a very very scary dog .
Big strong and dangerous and nearly killed a smaller dog who he attacked while it was on a leader .
Poor pony it should not be too difficult to trace the owner and the police should be invovled it might not be a animal next time .