Originally Posted by neurodoc
Jessica, I have such empathy for your situation with the dog, having gone down exactly the same road. One thing we didn't try but might help is a muzzle. You might ask the vet behaviorist his/her opinion of them.
You can't have the dog wearing the muzzle 24/7 and it in no way alters the behaviour. The dog has to be retrained by someone with a very strong energy, lots of time, and a great deal of patience. Carter would do well with a large male owner who knows a great deal about dogs.