What is a break-away halter?

Often when you try to tie up a horse and they spook frequently, we use a thing called a breakaway halter. This halter is designed for the horse to spook and the halter to give into the horse. Usually normal halters will not break from a horse's struggle, and will result in the horse hurt and/or the fence you tied it to broken. But breakaway halters will release the horse and the halter isn't broken permanently. Some people believe if you let a horse breakaway without a consequence they will try it every time to get out of work. Others believe horses only breakaway due to a true spook and don't want their horses hurt.