Awe the adolescent phase. Every dog goes through it. It can vary in severity from barely noticeable to feeling like the dog fromMarley AND Mejust possessed your dog. Adolescence usually starts between 6 months and 1 year and lasts for a few months. Luckily it comes and goes. Your dog may be ornery for a week then return to your loving companion for a week then the orneriness returns and then disappears again. In the interest of full disclosure, ornery may be sugar coating it a bit. What you’re likely to experience is major attitude no different than a rebellious teenager.