The symptoms sound very similar to a pony we had in for a client. They bought him as unbroken, but when we started him it was obvious he had already had someone attempt to break him in. He had explosive episodes, and could not canter without going disunited and bunny hopping. It was diagnosed as...
As a new member, just thought I would say Hi to you all. I have a few years experience with horses. I am an owner/rider, and also used to work with horses as an instructor and comp groom. I no longer do this as too damaged!! Ha ha. X