Got this from http://www.cdc.gov/niosh/nasd/docs/as15300.html

"If at any time the horse needs to be restrained, and tying is not enough, there are different methods to choose from. If the chain from the lead shank, over the nose, does not work, then a twitch is most commonly used. A twitch may be applied to the upper lip, the ear, or even the lower lip. Many different types of twitches are available, the most popular being a long handle with a loop of chain or rope at one end. To apply the twitch, place fingers through the loop at the end of the twitch, grasp the upper lip with your fingers, pull it through the loop, and twist the handle until you get a firm but gentle hold on the lip. Do not place it too high, because it will interfere with breathing or too low which will cause pain. Tighten it only if the horse acts up and loosen it as soon as it becomes manageable.

Do not use the twitch to move the horse around. A twitch should not be left on for more than 15 minutes at a time. If left on longer, numbness, or in extreme cases, permanent nerve damage may occur.

Assuming the twitches are placed and used correctly, they provide an effective and harmless method of restraint."

Me 'n' the nags of the world still reckon they are instruments of torture - why else would such bloody great animals instantly become meek and mild?

stales