A martingale leash works similarly to a martingale collar. It has two sides that tighten when the dog pulls, instead of one like on a slip leash. This way, the dog feels the pressure when they pull but don’t get choked. When it’s not in use, it is loose, making it very easy to put on and take off. This style of leash is popular with dog rescues, as the dog doesn’t need to wear a collar while using it.