What does it matter if you open a dog hole next to the gate?

This is actually not called a dog hole. The name is different in different places and in different periods. In the past, it was actually called Longmen, in the hope that one's family members would be named on the gold medal list and become high-ranking officials. Some rural areas still call it this way. There is another type called Cai Shui Gate (also called Feng Shui Gate), which is to hope for good luck and good fortune! Calling Goudong is just a habitual way of saying it in spoken language!