Aggressive mixed breed
I have a nine year old mixed breed dog. Hes lab and something... I adopted him 4 years ago. He has acted aggressively towards dogs in the back of pickups since I got him. He gets along great with my German Shepard and with my kids dogs when they're together.(all 5 of them) I can bring other dogs into my yard and hes fine. However if we're out walking, whether he's on leash or off and we come across another dog, he tries to attack. He sounds like hes trying to kill it but even if he gets to it, he doesn't hurt it and will walk off after a few seconds. He's aprox 95 to 1000 lbs and normally very sweet. Even though hes never hurt another dog, this is obviously not acceptable behavior. This has escalated quite a bit since I got him and seems to have gotten worse since I adopted my German Shepard a year ago. (He is aprox 2 years old). I'm wondering if he could be protective of his younger friend? or could it be getting older? I'm at a loss.