Dogs go through changes during adolescence just like people. Changes include biological, psychological and physical changes, all affecting behaviour.
It is especially important now, to continue training during this continued developmental period of 6 to 18 months, and longer for some. Your once very sleepy puppy, used to relax and settle after a walk or playtime, but is now restless and won’t settle down. Adolescence pups often become easily overstimulated, lacking impulse control, exhibiting on leash frustration, jumping, mouthing, and pulling on leash. Dog / dog social interactions often change, for the worse, and things that they were used to, or new things may suddenly seem scary now, (secondary fear period).