All that a horse needs to do to get hurt is to go to scratch his ear & get a hoof caught in a halter, I must add. I don't know if your halters are break-away's. Halters, especially flat web ones, are also itchy & cumbersome for the horse.
Too funny, surprised the ball lasted as long as it did.
One of my old trainers had one of those balls for her yearling to play with. She thought that my appy would like it too, so we put the ball in the round pen with my mare. She bounced it once, then looked at us like "You think I'm going to entertain YOU?? Get real."
BTW, I love the Veiga line of Lusitanos. Super athletic line.