We adopted this lab from the Humane Society when he was 6 months old. We are in our second obedience class, and he seemed to be doing better, but now he has gotten right back where we started if not worse. He is barking/growling at us, biting, grabbing pillows off of couches, getting up on the counters, taking things off of tables, etc.

We take him for 2 walks a day, or one walk and one trip to the dog park to run with the other dogs, so it shouldn't be an exercise issue. We try to be pack leaders, and know it's importance. What is crazy is that when he's done something wrong, he cowers when we see him like he knows he was bad, but still misbehaves afterwards like nothing happened. We've used a shock collar before, but that didn't help much. Our obedience school tells us not to spank him because we will lose the respectful relationship that we've built with him. They told us to gently grab his jowls and shake it while saying "no". This only works briefly.

What can I do?