Don't feel bad, I've owned horses since 1985 plus worked at a big training barn for about 12 years, and have NEVER known of a horse to play with a ball! I used to wonder why on earth they even made these stupid things! Twister discovered an old ball out in his paddock one day though and just went crazy over it! It must just be some natural drive he has for it or something!
One day I was sitting in my office which overlooks his paddock and I saw him running around with something small in his mouth. I went out to see what it was and he had stolen the next door neighbors football and was running around with THAT in his mouth! LOL
I would love to get him one of those giant balls. Where do you find those?