Elizabethan collar
The veterinarian places the collar around the neck of an injured animal so that it cannot bite or lick the injured part of its body.  For example, a dog with a cut on its skin might need medicine placed directly on the cut. The dog might try to lick the medicine and poison itself.  An animal that has had surgery might try to pull out its stitches.  An animal with a broken leg might bite into its cast and try to pull it off.  If it is wearing an Elizabethan collar, it cannot do this.