I was at a Quarter Horse Breeder's place and we were looking at a three year old that he had sold to a guy who would make payments .. he broke the horse out and used him to snag post and poles out of the South Hills with a permit.
Later, he quit making payments and my friend took him back to discover he had four vertebrae out on his back .. but when the horse chiropractor came out and started to knock them back in place with a mallet on flesh .. he had the good sense to run him off. Got a lady that did it with her hands .. soft .. fist on a hand to cushion the blow.
Have you ever read "Five Years a Dragoon" by Lowe .. three thousand miles on one horse in one summer. I know you would flip over "Child of the Fighting Tenth" by Birdie Hooker .. and .. "No Life for a Lady" by Agnes Morley Cleaveland. I buy mine used from Alibris Dot Com ..
If you get too far from the stone age .. things go haywire.