Nip, nibble, bite, chew, however you phrase it, mouthing is normal canine behavior. There are a variety of reasons your puppy -- or dog -- is using his front teeth to nibble or chew on things. Your job as his parent is to teach your dog what's acceptable to nibble on and what is off-limits.
Nipping and nibbling is instinctual puppy behavior. At a young age, while still living with mom and litter mates, most puppies learn bite inhibition. As puppies grow up, they toss, tumble and play together, which includes playful nips and bites. Every so often a pup will bite a little too hard with his razor-keen teeth, causing his sibling to admonish him with a sharp yelp. After enough encounters like this, a puppy learns how to play-bite without hurting his pal, meaning the play session can go on uninterrupted. If your dog is nipping, he could be engaging in a bit of affectionate play, hearkening back to his days with his mom and litter mates.
Perhaps your dog doesn't like to be left alone and the stress of being left behind causes him to nibble. Sometimes a dog with separation anxiety will chew, lick or suck on things to help him relieve the stress of the situation. A toy, favorite blanket or even one of your shoes may be be the object that soothes his anxiety. Teething is another reason for nipping behavior. If your dog is still a pup and in the teething stages, he's probably chewing on just about anything that will provide him relief from the pain of teething.
Dog Nips Dog
Separation anxiety also may cause your dog to nibble on himself, as he seeks to self-soothe. Allergies, boredom, dry skin, pain, hormonal imbalances and parasites also are potential causes of compulsive self-chewing or nibbling behavior. Left unchecked, your dog could develop a hot spot, an irritated, wet, red area that can become painful and large quickly. If your dog spends a lot of time nibbling on one spot, he should see a vet.
Teaching How to Play
If you're concerned about your dog's nibbling behavior, pay attention to the context to determine why it's happening and if it's problem behavior. If he's nipping at you or anyone else, he needs to learn right away it's not acceptable. The American Society for the Prevention of Cruelty to Animals recommends taking a page from his first family by letting him mouth on your hand until he bites hard. When he does, respond with a high yelp and allow your hand to go limp. Praise him for stopping and resume the routine up to two more times in a 15-minute period. If your high-pitched squeal doesn't do the trick, admonish him with a stern "too bad" or a time-out routine, where 10- to 20-second breaks of ignoring him replace your yelps. Your ultimate goal is to reach a point where you only feel pressure from his mouth when you play.
Chew on This
If your dog's nibbling behavior includes precious objects, admonish him with a stern "uh oh," and replace the off-limits item with something he can chew. Spray chewing deterrents, such as a bitter spray, will help him learn what he can and can't chew on. Offering him old shoes or other household items will confuse him about what he can and can't chew on, so stick to chew toys for consistency.