Adolescent Mouthing

Mouthing is common and normal for puppies

Normal puppy mouthing allows puppies to learn bite inhibition.  "Bite inhibition" sounds like stopping dogs from biting altogether, which is misleading.  The skill described by the term could be thought of as similar to children's development of precision use of their hands.  Bite inhibition allows dogs to coordinate the bite they intend to deliver with the bite they actually deliver.  

Since fair play is the primary vehicle dogs use to bond, and since dogs communicate with each other via tactile as well as visual cues, development of this skill is crucial to a puppy's ability to "talk" to, make friends with, and bond to other dogs.  A dog who bites harder than he thinks he is biting will be ostracized, at best.  At worst, such disproportionate interaction can provoke another dog to retaliate.   

As social animals, dogs are highly motivated to avoid both conflict and ostracism.  

Adolescent dogs who do not use their mouths appropriately could be described as "developmentally disadvantaged".  Often, mouthing in older dogs arises when they fail to receive with socialized adults when they are needle-toothed chompers.  Oddly, however, I find that dogs who have a genuine bite inhibition issue (not aggression or emotional reactivity) remediate much more rapidly than dogs who have other social deficiencies.

Mouthing behavior in adolescent dogs is utterly abnormal, and a problem behavior, not just an inconvenience.

Dogs who put teeth in contact with human skin can have a variety of motivations.  Most owners do not have the ability to identify the difference between a dog delivering a mild-to-moderate "correction" to a non-compliant human, a dog INSISTING on play with a human, a dog thinking she IS playing with a human, and an all-out emotional meltdown of reactivity, whether overwhelmed with fear for her life, or a blind rage of venting frustration into anything close enough to nail.

Neither this article, nor a book nor a stack of books will teach you how to correctly identify the subtle behavioral and body language indicators necessary to make the diagnosis.  Hours and hours of time observing live, moving dogs (not photos or drawings) under the tutelage of some of the best trainers around is the only way to learn to speak the language.  

Addressing the problem

Like almost every problem behavior, resolving the issue hinges on a correct diagnosis, development of a realistic plan of attack, and continuing check-ins with your professional.  The approach you use is up to you and your professional

All plans should provide a rehab phase of additional time investment, a tapering phase, and eventually a maintenance lifestyle is reached.  During the rehab phase, besides following the problem behavior resolution plan, always provide additional physical exercise and additional training activities.