8 months old? by now she is nearly 9 months, hopefully you have made some progress but I would highly suggest you crate train that dog. If she is tearing up your house while you are away she has not earned the freedom to be left alone when you leave. Crate the dog anytime you cannot directly supervise the dog. Not to be harsh, but you can come home to a dead dog one of these days if she gets into the trash, chokes on a couch cushion/stuffing, you never know. Your dog will also thank you for crate training her. The crate becomes a safe place where she can relax and be calm. I'm willing to bet your dog is nervous/anxious and doesn't know what to do with itself, therefore getting bored and chewing on whatever it wants.
I would highly suggest you start researching 'balanced training' as you said it appears positive reinforcement has spoiled her. the dog needs structure, rules, and boundaries. there is no point of punishing your dog hours later for chewing up your couch once you get home, she doesnt know thats why u are punishing her. you need to catch her in the act. this goes back to, you need direct supervision on the dog otherwise its in the crate. you need to teach that dog basic obedience. such as.... sit, down, place, recall, heel, wait for food, wait at thresholds (car door, house door, crate door).
hope this helps.
Last edited by yostuhfoo; 08-15-2016 at 11:06 AM.