Why is my puppy aggressive towards other puppies but good with older dogs?

Introduce them to one another gradually. First, by allowing them to hear and smell one another through a closed door, then by sight without physical contact, then supervised contact. You will need to progress gradually through each phase. Correct any aggressive behavior immediately and praise good behavior consistently. A pheromone product, such as the Adaptil collar or DAP plug in diffuser, may decrease any anxiety or aggression.

If your dog does not get along with other dogs it was probably a very bad idea (and a very stressful one) to bring a new puppy into the house. A new puppy can also be hard around a newborn as they aren't yet sure how to interact with each other. You can try to continue to get the two to get along by starting with limited introductions that are supervised, however if a fight breaks out the interaction should be stopped immediately and started again later. Never leave the two unsupervised together as even a good play sessions can cause accidental injury. You can also use baby gates as a way for the two to "meet" each other without being able to physically be together. If fights are continually breaking out, talking to a trainer or behaviorist that can observe within the home is best.

Have her spayed. This will decrease hormones which can drive certain behaviors. Slowly acclimate Panda to one dog, then another and another. Do this on "neutral" ground and on leash. Correct any aggressive behaviors immediately. Use praise and small rewards as she progresses. The use of a pheromone product, such as the Adaptil collar, may also help to ease her anxiety/aggression.

It’s hard to know if this is true aggression, aggressive play or if Ted is simply not picking up on social cues. Neutering Ted may help to dampen behavioral or aggressive tendencies but behavior modification is still needed. Your best option is to work with a professional trainer who can help teach you how to modify Ted’s behavior for more polite doggy play dates. You may also need to be very selective about the dogs Ted is allowed to play with. Best of luck.

Consider a pheromone product, such as the Adaptil collar, which may decrease any anxiety or aggression. You will also need to desensitize Jojo to the presence of larger dogs. Do this by introducing a large dog for ever increasing periods of time. Begin at a distance and gradually bring them closer. Correct any negative or aggressive behavior immediately and consistently praise good behavior and positive reactions. It will take some time, so be patient. You may need the assistance of a certified trainer or veterinary behaviorist.

A gradual introduction would be recommended. Separate them for a few days, then begin anew. Jackson may eventually become acclimated and accepting of the new dog, but it could take time. Consider a pheromone product, such as the Adaptil collar or DAP diffuser, to decrease any anxiety or aggression. Correct any aggressive behavior immediately and praise and reward good behavior.

As a puppy, Zeus does not know what is appropriate behavior towards strangers and other dogs, and he is reacting with aggression when his personal space is invaded. This is a very important time in Zeus's life where he needs to learn how to socialize with other people and dogs. He has to be taught how to interact correctly so that he doesn't display aggressive behaviors as he grows up. One of the best ways to do this is to enroll him in puppy preschool or training groups. I would speak to your vet for a recommendation to one of these, where he will learn how to react appropriately when approached by strangers or other dogs, and can also learn basis commands such as sit, stay, and lay down.