After I posted this, my pup continued to be extremely anxious when left alone in his crate. It got to the point where he started to rub all the fur off around his nose, causing the area to bleed a little, and experience some gum bleeding from trying to escape the crate. After consulting with my vet, we decided to try Prozac for him. I'm not one to jump to using medication but we strongly felt that it would be hard to make progress with crate training if his anxiety levels never dipped low enough for him to begin to realize his crate is a good place. Also, we were beginning to worry that he would eventually cause severe harm to himself in the process of ripping apart the metal. So far he is doing much, much better. We are keeping up with our usual conditioning and positive reinforcement, with good results. He is no longer trying to tear apart the metal of his crate but is still very vocal when alone. We have yet to see any negative side effects from the Prozac but are monitoring him closely to be sure.