Things You'll Need
Instructions
Take your puppy to veterinarian in your area who specializes in dogs. Getting your puppy a checkup helps eliminate any health factors related to its aggression with other dogs or people. Explain to your vet that the puppy is showing signs of aggression.
Evaluate your puppy's home environment. If there are things in the home causing it to be aggressive, eliminating or working on these problems is necessary. Examples of disruptive influences include leaving the puppy alone frequently and for long periods of time, leaving the puppy alone with an aggressive or overly playful dog, yelling frequently and other related issues that may disrupt your pup's emotional balance.
Make the environmental changes necessary to improve your puppy's disposition. This may require installing a doggy door into a fenced-in play area for when he is left alone. It also may include separating the puppy from other pets while alone.
Socialize your puppy as much as possible. Hook him up to a leash and harness and take him to dog parks and other pet-friendly places for socializing with puppies his age. Gradually begin socializing him with full-grown dogs. Make this part of your daily routine; 30 minutes to an hour a day at a dog park gives you time together to bond while keeping him social to avoid aggression.
Reward your puppy with treats and positive phrases whenever he socializes with another animal without fighting. Eventually he will connect his good behavior with the positive attention as he develops.