My Demu used to have this problem. Everything on the ground likes to stuff it into his mouth. Finally I forced him to change. Put his favorite food on the ground, such as dog food. When he came to dinner, he stopped him severely. If he doesn't listen, call him. Let him know that things on the ground are not edible. After repeated training, put the dog food in the dog basin. You should make a slogan for him to eat. Only dogs in our family dare to eat. You can do the same. After severely stopping him from eating on the ground, hit the dog basin, or put the dog food in your hand for him to eat. After repeated training, let him know that he can only eat when you give this order. Be patient, dogs are different from people after all. But the dog is very human. He knows how to look at your eyes and judge by your tone.

Remember to help him review this course every day. Keep an eye on him when you take him out. If you find something to eat on the ground, stop immediately. For example, calling his name in a harsh tone will distract him. If you don't listen, go and spank. Over time, you will change back.