I had a pony when I was 8. Got him for free, and found out why he was free pretty quick.
The little jerk liked to bite, kick, throw kids off and pretty much anything else he could get away with.
But in hindsight, I was glad I had him, because he taught me how to stay on like glue.
My advice about ponies? They are the devil. Get a horse for a kid. Not a pony.