The term "aggressive dogs" refers to canines that exhibit behaviors such as growling, snarling or biting when they feel threatened or provoked. These dogs may lunge, bark loudly or show their teeth in an attempt to intimidate others and protect themselves from perceived threats. Aggressive behavior in dogs is often a result of poor socialization, lack of training, genetic predisposition or fear. It can be dangerous if not managed properly and may require intervention from animal experts or trainers to help the dog overcome its aggression issues.