Cute and cuddly with a bite. Biting and chewing can be dangerous at an early age. Aggressive puppy behavior can be cute, however it may lead to horrible quickly. If you puppy bites down on someone’s child they will be put down in some states or countries. Train, socialize and play with your puppy and teach them biting is bad. Serious dog aggression starts when they are puppies and will be difficult at an older age to retrain. Reasons puppy aggression starts. Boredom, being alone all the time creates anxiety and frustrations in a new puppy, they don’t understand. Many pick up behavior from other dogs, which can be due to being treated aggressively. Any injuries, such as cuts must be treated, genetic diseases, aggressive behavior is at time a protective response. Some dogs have “rage syndrome,” which causes them to act erratically at times, this will need to be treated by a vet. Large breeds are driven to protect there little territory against everyone, so be on top of your puppy training from the beginning and have the results you desire.