you might enjoy this blog by Rhonda Lane. There are comments also of interest. I used Dr. Womack's book "Echo of Hoofbeats" for a lot of Tennessee Walking Horse history, and also history of soring in my book: "The Horse That Wouldn't Trot.
I talked to Dr. Womack while I was writing my book and got permission to use his information. Soring is still a very "sore subject" in the walking horse world, and so far efforts to STOP it have failed, but many keep working. My memoir book is my effort to help by telling true stories, but not dwelling at nauseum about the subject.