It's for the dog's health that he should be neutered. There are no questions about it. And, as for the prong collar, it should be used as a training device, and, if used properly and in conjuction with persistent, consistent training, will help your dog be more obedient and possibly less dominant. It is a training device, though, and, I don't think it should be used for the entire life of the dog. A lot of people seem to use it because they haven't trained their dog, and, the dog is walked with a prong collar for life. I think that defeats the purpose of the collar to begin with. With such a large dog, I would look into one on one training with a professional as well as using a prong collar for training.