Biting is never acceptable behavior in a dog. You must establish yourself as the alpha of your dog´s pack or biting behavior will continue. A biting dog will eventually be a dead dog in many jurisdictions. You need to teach your dog not to bite for their own protection.

1. If you have a puppy that bites, you need to stop that conduct in its tracks. One way to do this is to "yelp" while pulling your hand away, saying "ouch!". This usually works to discourage further biting. You need to follow up with a stern "NO," then retreat from the pup with a mad face. Don´t worry. You can return to be kind again to your pup in a few minutes. For the moment, let you pup realize that biting you was not acceptable.You must be consistent. By allowing your young dog to bite flesh EVER is trouble for you and your dog. Cute little puppy nips will become adult bites, and this can become a major problem in the long run.

2. If an older dog suddenly starts biting or snapping, a trip to the vet may be in order. Your dog may have a medical problem and is biting to protect himself. This doesn´t mean that you can allow the biting, just be aware that there may be a clinical reason for it.

3. Some dogs are predisposed to biting by genetics or isolated puppyhoods. These dogs can usually be taught not to bite, but a few sessions with a reliable dog trainer may be needed.