Crupper is a piece of tack used on horses to keep a saddle or surcingle from sliding forward by tethering the saddle to the root of the horse's tail. It consists of a buckle to attach to the back of the saddle, an adjustable strap to set the crupper's length, and a final strap (sometimes padded) that passes around the root of the horse's tail.
Cruppers were traditionally part of the standard equipment of cavalry horses, but were largely abandoned by cavalry regiments in the 19th century, upon the arrival of better-fitting mass-produced war saddles. Cruppers continue to be part of the ceremonial tack for some cavalry regiments and tent pegging teams.
In civilian use, cruppers are usually seen on round or overweight ponies or mules. They are also common on driving horses.
Putting On the Crupper
The skirt of the tail is doubled over and slipped through the rounded strap. There should be no tail hair under the tail piece of the crupper. The buckle-end strap attaches to a ring on the back of the saddle (which may need to be added by a saddler, as most saddles no longer have a D-ring on the cantle), or to the middle ring on a surcingle. It should be snug enough to keep the saddle in place, but not so tight that the horse is irritated or the skin of the tail is damaged.
A crupper must be kept very clean, or it can abrade the skin under the tail and cause the horse to start kicking. A poorly adjusted crupper can cause severe discomfort, angering a horse or causing sores on the horse's dock.
It is advisable to longe a horse with a crupper before riding him in one, so he may get used to the feel of it under his tail.
Fitting the Crupper
The crupper must be adjusted so that it is not too long, which will not allow it to work and may cause soring, or too short, which will pull the tail out of position and may cause the crupper to come off. It should be placed up under the root of the tail, but without any forward pulling.
