The reason will surprise you

One of the main concerns when thinking of getting a dog and bringing it into your home is certainly cleanliness and hygiene! A dog is obviously not capable of paying close attention to where it is putting its paws, so, naturally it picks up all kinds of dirty things, especially if it is a long-haired dog!

However, even if there is no natural instinct, to be tidy — dogs can still be trained and consequently, learn how to avoid creating a mess in the house! Instead of bouncing around on the front porch after their walk; the four pets line up single file at the door and patiently wait to have their paws wiped.

In fact, in this video, we see a woman who has managed to train her four Golden Retrievers to wait patiently at the front door, so that she can clean their paws before they are allowed to enter the house!  Amazingly, the owner does not have to pick up their feet to clean them; the dogs are trained to lift their paws.  When all four paws are cleaned he is allowed into the house. The lineup of dogs moves ahead in a perfectly orderly fashion. Each dog steps forward one dog length and settles into their patient stance. The second dog takes his place for his turn to receive the paw cleaning. These canines definitely have good manners and a great deal of patience. If only all of our dogs could be this well-behaved after a day of romping around in the yard!

Source: www.tropcute.com