Penny has some issues with aggression. From what I've researched so far, I believe it is territorial/protective aggression. She is 2.5 yrs old now.
She goes nuts when someone comes to the door, when there's activity outside, noises, etc. = territorial aggression. Oh, and she now marks when we go on walks.
She also tries to "get after" people when we are on a walk with her or standing outside the house with her. She struggles to get to them, barking her head off, same with other dogs. Now as a puppy, she would only strain to get to them and then shy away when they tried to pet her. As she's gotten older, it's turned to barking. And she hates bicycles (unless DH or I are the one on the bike). = protective agression
Last night on a walk, she pulled and barked at someone in the neighborhood. Since he was in our community, we stopped to say hi. Usually after a moment, she will sniff their legs and settle down. Not with him. She actually jumped up and snapped at him, of course just as we were telling him not to worry, she won't bite.
So, we are discussing getting help for her aggression. I do not want this to become a bigger issue as she gets older. We plan to have children in the next few years (and many of our friends already do) and we can't have an aggressive dog.
When she's at home, she's the most loving dog in the world. So where do we start? Books? A trainer?
I know she is under-socialized. She picked up at-home training so quickly, and they didn't have puppy classes in our old town so we never took her.
We'd appreciate any suggestions to nip this in the butt.