Soring
Soring, or "big lick", is defined as the application of any chemical (e.g., mustard oil or diesel fuel), mechanical agent (e.g., overweight chains), or practice (e.g., trimming a hoof to expose the sensitive tissue) inflicted upon any limb of a horse, that can cause or be expected to cause the horse to suffer physical pain or distress when moving. This results in the horses picking up their front feet higher and faster than they would do in their natural gait. Trainers use soring to give a horse a highly animated gait in a short time period rather than spending time training them to perform this gait naturally. People who sore their horses believe that it gives them a competitive edge over other horses in the show ring. However, soring is illegal in the United States under the Horse Protection Act of 1970. Tennessee Walking Horses are not allowed to be shown without passing a USDA and HPA inspection for soring and physical inspection; they are not allowed to have scars on their pastern as it is associated with soring. Other breeds that have a history of soring include the Racking Horse and the Spotted Saddle Horse.
Soring is often mistaken for padded performance. The pads, sometimes called "stacks", that are seen on Tennessee walking horses in padded performance are made of rubber and are light weight. When a Tennessee walking horse is seen wearing rubber pads they will usually also have the addition of 6 oz chains placed around the pasterns to make the horse aware of the action of its front legs.