I had a friend who has a machine and uses it on horses and people for a living. I have had it used on me (I have scoliosis and some disk problems) ask well as on multiple horses
depends on the horse and the person. I did mine every couple months... My horses have all seemed to enjoy it. The grey in my avi cant get close enough to the lady who does it. I will say though it made me feel like I was going to puke when I had it done to me