Horse soring is the unethical and illegal practice of deliberately inflicting pain to exaggerate the leg motion of horses to gain an unfair advantage in the show ring. It involves the intentional infliction of pain to a horses legs or hooves in order to force the horse to perform an artificial, exaggerated gait. Soring can be accomplished through the application of caustic chemicals, such as mustard oil, diesel fuel, and kerosene, to the horse's limbs, causing extreme pain and suffering. A particularly egregious form of soring, known as pressure shoeing, involves cutting a horse's hoof almost to the quick and tightly nailing on a shoe or standing a horse for hours with the sensitive part of his soles on a block or other raised object. This causes excruciating pressure and pain whenever the horse puts weight on the hoof.
The legal definition of soring in the Horse Protection Act of 1970 is: (A) an irritating or blistering agent has been applied, internally or externally, by a person to any limb of a horse, (B) any burn, cut, or laceration has been inflicted by a person on any limb of a horse, (C) any tack, nail, screw, or chemical agent has been injected by a person into or used by a person on any limb of a horse. Despite being outlawed by Congress and several state laws, soring is still widespread in places like Tennessee, Kentucky, and other areas.