Ask your Vet if you could read the latest issue of JAVMA (Journal of the American Veterinary Medical Association) March 15th, 2012, Volume 240, Number 6.
There is an article on page 632-636 on soring practices in the Walking Horse world. High Time for Change; Malinda Larkin. I think you may find it interesting. You may be able to request a digital copy of the article for your blog.