Hello, I'm new to the forum and am the proud owner of (dad to) two 9 month old german shepherds, one male (Link), and one female (Zelda). We've had both pups from 8 1/2 weeks and have followed all of the guidelines for raising litter mates (separate kennels, socialization, walks, etc. until about 20 weeks). The reason I am writing is our male seems to have developed aggressive tendencies when he's over-stimulated. There have been a couple near misses with other dogs (fortunately NEVER with people), we've wracked our brains to try to try to identify any pattern and the only common thread is him making his "excited whine" immediately prior to each incident, its the same whine he makes when he's going to get fed, knows they're going to the dog park, going for a walk, etc. He doesn't normally exhibit signs of dog aggression in normal encounters, the incidents have all happened well after any initial introduction and after a playing for a while. Does anyone have any advice on what we should do other than be hyper-vigilant to his behavior? Is this normal for a male of his age, is it something he'll outgrow? Also yes, he is neutered. Any advice would be appreciated.