I have recently adopted a GSD possible Great Dane mix from a foster mom who had him since he was 2 months old, he is now 11 months. I have only had this dog for two weeks, and in that time he has displayed some odd behaviors.
The first week we had him he was sweet and did not display any signs of aggression. We started establishing who was Alpha right away. Then out of the blue he started barking at people on his walks. At first he would stand next to me and bark a few times. I would distract him away from barking and reward with a treat. Then he started darting towards people and getting close to them and barking, I would have to pull him back. And finally he acted like he was going to bite this one walker, he was on a leash and was pulled back, but then lunged for her again. His eyes had a glazed look in them like he was somewhere else, and could not hear me. The odd thing is, he loves other dogs and has no aggression towards them, he will not chase small animals, and walks slightly behind me on the leash. This is just the first part, but I feel it can be corrected with more training.
The part that troubles me the most is that I'm not sure if there is something wrong with him. We can have friends over for hours. They pet him, give him a treat, etc. and he wags his tail puts his head down and enjoys the attention. Then out of the blue, he will just start growling, barking, and threatening to bite, completely unprovoked. He is not food aggressive, and allows anybody to take toys or treats. It makes it hard to have people over, or take him anywhere, because he is unpredictable.
One time he was laying on the floor peacefully, and our friend who had just played with him an hour before, shifted his body weight, and the dog jumped up ran to him and started barking as if he had never seen him before. Does this sound like a behavior that can be corrected, or is there something wrong with this dog. BTW, this doesn't just happen in our home, it happens when we visit others homes as well. Ideas? I do have the option of giving this dog back, the foster mom said he never showed this type of aggression in her household, she however has 4 other dogs that always picked on Jack (the dog I have now), I have no other dogs in my house. But I want to keep him if this is something that can be corrected. So I'm asking for help.
Jenn