Random aggressive 10 month old Dutch Shepherd
Three months ago I rescued a a dutch shepherd. He is thought to be about 10 or 11 months now. He has always been a sweet dog and is very social, playing with dogs, adults and children. He has had random bouts of aggression toward certain people though. In the three months that I have had him. He barked and growled at a homeless man, he barked at an old man carrying a beach umbrella. He barked at people at the dog park that pick up trash with sticks and the guy changing the garage bags. Today at the dog park, he barked at an old man carrying coconuts. He ran up to him and was looking to grab the coconuts. I called him away and the man when and put the coconuts down on a table, when he walked back over, my dog nipped him multiple times at his pant leg while barking and circling him. he continued to circle him to prevent me from grabbing him to make him stop. He has never bit anyone before. Before this man walked up, my dog was playing with four other dogs and there was a man, his son, and two women there and he wasn't even remotely aggressive toward any of them. We go to two dog parks and we go almost every day and he is fine. What things could be setting him off? I have noticed that it appears to be only men and they have all had something in their hand, except the homeless man but he was drunk so maybe he was acting weird. Is he at an age where he may be getting aggressive? What's the best way to curb this. I don't want him biting.