As a 5 Star Dog Trainer 21 years and Behavioral Specialist I found my expertise in Aggression in puppys and dogs. Yes, puppy’s can have aggression but if caught early it can be eliminated, they will not out-grow or neutering will end aggression. I’ve also found that some behaviors clients believe to be Aggression is just bad behavior and they weren’t given the education on how to get the behaviors they want out of their pet. NEVER resort to punishment or negative equipment equals negative results.