My gsd is 15 months and had tolerated children touching him, up to about 9 months of age. When some children boisterously ran towards us and hurling stones at him. Since then, he hated children and would be on high alert when he hears a high-pitched voice (kids' voices), and bark at them if they moved towards us. Especially if they were on bicycles or skate scooters.
However, he generally hates cyclists if they were near to us. If they were across the road, he's fine.
He is also very aggressive towards stray dogs due to bad experiences. If it was somebody's pet, he's okay. Even if the puppy was running off-leash towards him. He is also well-behaved at the clinic towards other dogs, even when a JRT snapped at him, he didn't react. I first thought it was breed specific, but recently a boxer-looking dog appeared in our compound, which I think is an abandoned dog. This dog keeps following if it spotted us, approaching in a friendly way, tail wagging and running happily, no growl or bark; just watching in a distance. He couldn't get near cos Magick is aggressive towards it. Growling, barking and charging towards it...
On top of all these, he is also very selective in whom he "makes friends" with. Mostly, he doesn't allow men approaching me suddenly, strangers. And would growl or attempt to charge at them. However, it seems if someone was addressing him instead of me and appear confident/ unafraid, he allows them to pet and even hug him. I'm of the idea that he senses the fear in those people and hence, behave in a hostile manner?
I am very baffled by his behaviour and would really like to hear of any advice or suggestions for him to be less hostile towards people.