The dog is strangled and panting heavily due to lack of oxygen. The dog needs to be untied immediately to prevent the dog from going into shock or suffocating to death. When you usually bring a leash to your dog, do not tighten the leash too tightly. Once the dog's breathing speeds up, it means that the leash is too tight and needs to be loosened immediately. You can choose a sling-type leash, which will not strangle your dog's neck.