Bridles for the horses may use a wide variety of bits or hackamores. Riders also often add a breastcollar to keep the saddle in place while traveling over rough terrain. Use of a crupper is not common, but sometimes seen to keep the saddle from sliding forward on horses. Protective boots may be used on a horse's legs, though boots also cause problems in some types of terrain (they may slip, can collect burrs and dirt, and if crossing water may become waterlogged, any of which can irritate the legs of the horse and lead to lameness), so use varies by the type of ride and the rider's preferences. Hoof protection varies from barefoot to the use of hoof boots and shoes.