A muzzle-nudge is where one dog gently nudges another on the muzzle with its own muzzle. It show friendliness, acceptance and is a pacifying behavior. Normally, it is a submissive, low-ranking or insecure dog that displays a muzzle-nudge.
The muzzle-nudge is a redirected behavior pattern. There are two explanations for this behavior. First, it originates from the puppy nudging its mother's teats immediately after birth. Second, it refers to the pup's nudging of the adult's lips in order to bring forth regurgitation. This is seen in puppies from five to seven weeks of age.
The muzzle-nudge may also be used towards humans. Dogs frequently nudge their owner's hand or leg to ask for attention.