Protective Behavior

it sounds like a really complicated mix of fear aggression and resource guarding, not protection per se. It also sounds like a very dangerous disaster-in-the-making behavior. I think you need some in-person help not internet advice. Find another behaviorist?

 We are not interested in seeking out another behaviorist at this time.

That's an interesting stance.  You must have a bad taste in your mouth from the last trainer.  I agree with mudpuppy...you've got issues that are best dealt with by a trainer.

Having said that, however.  Your dog needs to understand that this is inappropriate behavior.  Do you practice NILIF with him consistently?  You should correct the dog when he is acting out.  Maybe you keep him leashed or tethered so you can control/manage him.

Yes, we practice NILIF consistently.  

We are not interested in a behaviorist at this time because we cannot afford one at this time.  So while I understand why that may be the best option, at this point it is not an option.   

 Dogs rarely protect their owners as much as they protect themselves, so if you have a fearful dog, which is my guess, then he is looking for backup, not getting any (or at least that's how he interprets it), and feels like the best defense is a good offense.  That does not mean that he is not also considering you as a resource and exhibiting possession aggression in some circumstances.  But, if the behavior happens only on leash, fear and the inability to escape could be driving much of this.  Either way, the solution lies in keeping people safe while you keep his attention firmly focused on you, and possibly doing some desensitization and counter-conditioning.  Your objective is to keep things below the threshold at which the aggression occurs (aggression really never disappears - it's a normal coping mechanism for dogs, just one that we would rather they not use).  But, if you are getting inconsistent results with the protocols you were given, then my advice would be to muzzle the dog when there's a chance he could aggress.  Morrco.com has a nice article on muzzle acclimation, and you can get a nice Italian basket muzzle there, too.  Good site for information on the types of aggression: www.k9aggression.com  HTH

One thing I tell people with dogs like this, is that there's actually good news.  Making decisions in this way is the sign of a clever dog.  The problem is that clever dogs need to keep their minds occupied. I'd have to lay eyes on the dog's behavior to be sure, but this sounds like a dog that "needs to be needed."

I agree with Anne that you need to develop his trust more.  Don't just work on basic obedience, leash walking, and the behavior modification stuff.

These behaviors can seem complex because there's a cycle of fear intermingled with the choices that are made.  The more a reactive dog gives in to its impulses, the more complicated and unpleasant its life gets.  That leads to more attempts to restructure its own world.  You've got to work very hard to give your dog the tools it needs to deal with life - please remember he's not mentally unbalanced, he's just an Einstein that's been plunked down behind the librarian's desk and told he can only touch the Dr. Seuss books.  Einstein would probably start breaking the rules and getting a bit rowdy too.

Sure fear may be involved, but as I mentioned, we left him with this other person over night and this person had no problems with Luther.  Luther was obedient and well behaved, even showed this other person affection.  It wasn't until we returned from our evening away and re-entered this other person's home that Luther began to get aggressive with this person.  

We have recently gotten Luther the gentle leader and that has helped on the walks.  He is slowly learning what behavior is and is not appropriate.  He had stitches on his nose, so we had to stop using it for a couple weeks and we noticed he was better on the leash overall.  So while we hope to eventually quash all aggressive behavior on the leash, this is mostly under control.  Our main concern is his behavior that I explained above. 

 Spiritdogs, thanks for the link to k9aggression.com.  Looks like there is some good information there.