I have heard of horses having them before, but had always thought it was due to poor muscling in the hind end, or from the horse over-working the muscles on one side. Or it could be caused from Jumping.
My horse is a fresh 5 year old, and has a Hunter's bump. He never jumped until I bought him, and even I don't jump him very high at all or often, since he's so green. We're taking baby steps.
He had very little to none muscling, and is just now starting to really form noticeable muscles since I've put him in 'training'. (Although I've been slacking w/ the rain we've been having & the insane heat.)
I would just like to know more about it, and what I can do to fix it. I have heard that I can get our Chiro. Out and they can adjust him. I've been told that will take it away.