A breastplate is a piece of tack (equipment) used on horses. Its purpose is to keep a saddle from sliding back. It is also a safety feature—if the saddle's girth or billets break, a rider may have enough time to stop the horse and dismount before the saddle slips off the animal's back. The breastplate is used on both English and Western saddles. Western riding involving working cattle use a thicker sturdier style than in English riding or Western riding horse shows. A breastplate is most helpful for horses with large shoulders and a flat ribcage. A breast collar as part of a harness is used to pull a load.

Tack is equipment or accessories equipped on horses and other equines in the course of their use as domesticated animals. This equipment includes such items as saddles, stirrups, bridles, halters, reins, bits, and harnesses. Equipping a horse is often referred to as tacking up, and involves putting the tack equipment on the horse. A room to store such equipment, usually near or in a stable, is a tack room.