A one-piece covering for a horse comprising: a chest covering which covers the horse's shoulders and breast and at least partially covers the horse's withers; a hood extending from the chest covering and having a hood opening at the end thereof through which the horse's muzzle projects; a hood opening enlargement device for selectively enlarging the hood opening such that the horse's entire head can be received through the hood opening; a girth strap for securing the one piece covering to the horse; and a connecting device for releasably connecting the ends of the girth strap. The inventive covering can also include a back covering which extends from the chest covering and covers the horse's ribs, loins, haunches, and croup and at least partially covers the horse's thighs.