Abstract: An adjustable muzzle for horses and other animals is described. The adjustable muzzle may comprise a flat sheet of material with a central portion and four side portions adjacent to the central portion, which side portions serve as flaps. The flat sheet of material may be moldable upon application of heat or other energy so that the flaps may be bent at an angle relative to the central portion to fit the individual shape of the animal's nose, mouth and/or jaw area, such as the snout of a dog or the muzzle of a horse. The muzzle device may be used to slow grazing or prevent chewing or biting of other animals, humans, and objects.