An undercover video captured the cruel practice of horse soring in Tennessee.

Footage released by the Humane Society of the United States (HSUS) shows a walking horse trainer applying kerosene to the legs of the visibly distressed animal in its corral at the Formac Stables in Shelbina.

The workers then wrapped the horse's legs after applying the chemicals, allowing the substance to penetrate the animal's flesh.

Moments later, before the competition, a man confronted the horse trainers.

In the video, he says: 'I just saw you put it down on your pants. This horse is under inspection right now, and I want to see it. Where is the syringe?'

The trainer eventually handed over the empty syringe and claimed he was not working with anyone when asked who owned the horse.

In the 1950s, some trainers began using soring techniques to achieve an exaggerated gait in horses in a short amount of time.

Soring practices include the application of harmful chemicals like mustard oil or diesel fuel, the misuse of mechanical devices such as heavy chains, or damaging the horse's hooves to expose sensitive tissue.

Horse soring is illegal under the Horse Protection Act of 1970 (HPA).