My 5-year-old German Shpherd has randomly started to act aggressively around my girlfriends dogs, but only when Im not there. I believe he is trying to assert his dominance over the other dogs while also trying to Alpha my girlfriend. I need help with training and breaking him of this because I cant have him just randomly attacking other dogs. He has been socialized his whole life and been fine with other dogs up to about 3-4weeks ago.
1 Pet: 1 dog