Yeah, you can break them of bad habits. I got ringer at 9 months and am having a lot of problems that I wouldn't have had if I raised him from a little pup. I'm trying to tackle one problem at a time and it has taken three months for me to see some real progress but he has stopped a couple of the bad habits that his previous owners let him get away with. It will probably just take more time since you need to break the bad habits and reteach the appropriate habits.