Horse harness

Full collar harness (top), breast collar harness (bottom)

A horse harness is a device that connects a horse to a horse-drawn vehicle or another type of load to pull. There are two main designs of horse harness: (1) the breast collar or breaststrap, and (2) the full collar or collar-and-hames.

For pulling heavy loads, a full collar is required because it distributes pressure over a larger area of the horse. An ill-fitting full collar can cause chafing on the horse's skin and can interfere with its breathing, as can a breast collar that is positioned too high.^{[1]: 38, 42–3, 82, 118, 129}

Putting harness on a horse is called harnessing or harnessing up. Attaching the harness to the vehicle or load is called putting to in the British Isles,^[1]: 219 or hitching in North America. The order of putting on harness components varies by discipline, but when a horse collar is used, it is usually put on first.

Harness components designed for other animals (such as the yoke used with oxen) are not suitable for horses and will not allow the horse to work efficiently.