Give your horse time to get used to wearing a crupper before you go on the trail. Shown is a crupper from Weaver Leather. Photo courtesy of Weaver Leather.

A crupper (a strap that runs from the back of your saddle and loops under your horse’s tail) helps to hold your saddle in place on steep downhill grades. Your horse will quickly learn to clamp his tail onto the crupper when he heads down steep slopes; his tail contains a large bone with strong muscles. Give your horse time to get used to the feel of a new object under his tail. Saddle him, attach a crupper, and turn him loose in a small, secure area with good footing. —Adapted from 101 Trail Riding Tips by Dan Aadland