I have a 6 month old GSD, lord she is a hand full. She can't get to my chickens but she did eat a camera this morning. I have found that a pinch collar works very well for her, leave the lease on it and when she needs correcting just pop it a couple of times and walk away without saying anything they learn that what they were doing is a never do it thing not a can't do it because your there thing, it doesn't hurt her but it get her attention. She just finished puppy obedience last night and received her puppy good citizenship award. MMMMM they don't live with her. Good luck with your GSD. It take a lot of patience.