I am sorry but I do not know any, I don't even live in Indiana but I go to a chiropractor, I am going to become a chiropractor, my brother is one and I could go on with the list.
Anyway...what I am getting to, is see if you could find a chiropractor that does humans and see if they would be willing to adjust your horses. Animals, including horses, are built almost exactly alike just animals stand on all four limbs, people stand on two. So for a chiropractor to adjust a horse, it wouldn't be that difficult, if they are a good chiropractor.
The good thing about chiropractics is that it is VERY VERY VERY rare for them to ever hurt a human or animal. Also, my brother got me this book for christmas that explains a lot of equine chiropractics and shows how you can do it yourself. Information of Alternative Medicine : Books : The Well Adjusted Horse: Equine Chiropractic Methods You Can Do
that's the book! I hope I was at least somewhat helpful. =)