Imagine having no thumbs.
The definition of a thumbless hand is a paw.
When you are thumbless, you rely on your mouth to pick things up. You also depend on the kindness of strangers (and family) to open and close the door.
So when Cassius the Corgi’s owner bemoans the way her dog bolts out the door and scratches at it maniacally to re-enter, I remind her that she has the upper hand/thumb in this equation.
Telling Cassius to sit and wait is fine. Except he dances and prances and is his antsy self until the door is open and he makes his mad dash out. If he is leashed, his owner goes flying out behind him.
Let’s back up.
The door is a boundary as well as a means to enter and exit. The last thing Cassius’ owner wants is for her precious pup to escape that boundary and get lost/stolen/hurt. She also wants a more controlled and dignified beginning to the daily leash walk.
Here is where those handy thumbs (pun intended) come in.
From Cassius’ perspective, the door opens because he stares at the crack where the door meets the wall. In actuality, his owner opens the door with her thumbed hand. By quickly opening and closing the door (several times in a row, being careful not to catch his Corgi snout in it!), it becomes apparent to Cassius that merely looking at that crack is no longer having the desired effect.
So, he looks at this owner instead. He backs away from the door. And magically, when he does this, the door opens. He waits until she says “Free,” the signal that he can safely go through the door. After performing this little ritual consistently at every door – yes, even the one to the yard for potty breaks – Cassius “gets” it. He automatically waits for permission, because his owner wants him to be safe, and because she is the one with the thumbs.
NOTE: All of the above is moot if you have a Siberian Husky, which don’t have thumbs but are able to open doors anyway.