Dogs with thumbs

I got up yesterday morning and proceeded to go about my usual morning chores; let the puppy out, feed the birds, get lunch ready for myself, shower, dress, etc.  As I was getting the bird food ready I heard a commotion in the hall and turned around to find the big dogs standing there with the puppy.  Now when I got up I closed the bedroom door and left the big dogs sleeping with Hubby.  This is now the 2nd time they have opened the door and gotten out of the bedroom.  I am firmly convinced that one of them is hiding thumbs.  That is the only logical explanation for these events.  Okay, it's either the dogs have thumbs or I didn't close the door tightly enough -  but that could not have been it....