The reasons why dogs bite the leash:

1. The dog wants to go out and play. The reason why the dog bites the leash is to let the owner take it out for a walk. The owner can give the dog more toys for it to play with, and can also prepare snacks or bones for the dog to grind its teeth.

2. The dog is chewing the traction rope for the purpose of grinding its teeth during the period of teeth replacement.

3. The dog treats the leash as a toy and bites the leash for fun.

4. The dog may not be used to the leash. The dog feels restrained and will naturally refuse to leave when going out, and may even keep biting the leash.

What are the functions of a dog leash:

1. The leash can prevent dogs from getting lost, prevent car accidents, and avoid being bitten by other dogs. Avoid sudden surprises.

2. If the owner wears a leash on the dog, he can control the dog when it runs around and prevent it from rushing to the road.