The dog peeing at the door shows that the dog has a strong sense of sovereignty. Maybe it's because dogs have been in this place for a long time and regard this place as their own territory. In this way, he declared his sovereignty and warned others.
In this case, the owner should stop it in time, otherwise the dog will slowly develop the bad habit of defecating at home. You can set up a special excretory place indoors so that the dog can go to the designated place every time. After many trainings, dogs will form habits.
The owner can also take the dog out for a walk after each meal and let the dog defecate outdoors. At this time, paper towels and plastic bags should be prepared to clean up the dog's excrement in time to avoid polluting the environment.