Our dog has developed a bad habit of getting into the trash recently. Today, he did it again and growled at my daughter when she went in the room. I went down there and he ran into his crate. I tried to lock the crate and he growled with his nose right up by my hand. I was afraid to lock it. He did this twice. I finally got it locked. Now I was going to let him out, but he is continuing to growl when I put my hand on the lock. He has never acted like this in the past. Usually, he goes into his crate when he knows he has been bad but lets me lock it. Any ideas about what could cause this? As far as I know, he doesn't have a bone or anything in there with him. He has done this when he has something he doesn't want us to take away. Any ideas about what to do to stop this behaviour?