A hot walker within the practice of horse management may refer either to a person such as a groom employed in the job of hand-walking hot, sweaty horses after a workout, particularly after work on a racetrack, or it may refer to a mechanical device designed for the same purpose.
Humans employed as hot walkers usually handle the horse on a lead rope and walk alongside the animal either to provide them exercise or until the animal has cooled down from exercise and their coat has dried. Management techniques vary widely, but a hot walker or groom might first hose or sponge the sweat off the animal, with or without the addition of liniment to the water, and while hot-walking they may periodically stop and offer the horse water to drink.
Mechanical hot walkers come in many designs, the most common consisting of four arms of heavy gauge steel radiating off from a central pivot point containing a motor to move the arms at various speeds, most often set to have horses walk. At the end of each arm is a short rope, usually a nylon rope with a snap at the end, which attaches to the halter of the horse. The horses on the walker go in a circle, and the hot walker can be set to go in either direction.  The motor is often on a timer that will stop after a set amount of time. There are multiple designs, including a type that has moving panels and no radial arms.
Basic safety on a mechanical hot walker includes having the horses under the supervision of a human at all times, not allowing anyone to ride a horse while on a hot walker, and if two instead of four horses are on the walker, to place them on opposite sides.