Humans have devised methods for restraining horses for thousands of years. Some form of restraint is usually required for veterinary care or special situations that might trigger the horse's defensive responses.
The type of restraint used depends on many factors, including but not limited to the situation, the personality and experience of the horse and handler(s), and the environment or facilities available.
The most common forms of physical restraint available are as follows:
Halter and lead shank with chain: The chain can be run either over or under the horse's nose to add a higher degree of control.
Creative physics: That is, using the horse's body to force the desired behavior. For example, holding up the left foreleg encourages a horse to keep its right foreleg on the ground so the veterinarian can examine it.
Twitch: This device was once thought to only distract the horse; however, it is now believed that it actually stimulates mechanoreceptors in the skin that activate a release of endorphins in the brain similar to those released during acupuncture. The most common types of twitches are the humane twitch, the rope twitch, and the chain twitch.
Stocks: Built on many larger farms as a form of restraint for physical examination, treatment, grooming, and breeding. Stocks restrict the movement of the horse by enclosing him on all sides. Most stocks are built out of tubular pipe, which reduces the risk of injury.
Chemical restraint: Many drugs are available for the restraint of horses. The drugs have a tranquilizing or sedative effect that makes many procedures much less stressful for the horse. Only a veterinarian should administer chemical restraints.