supernoodle

The fact your dog is communicating with you by giving you warning signs like growling is actually a good thing, and means this is a very manageable case. The "trading up" method, and the basket muzzle are good measures, and can sometimes be enough, although they both have their weaknesses--you might not always have a higher value treat to "trade up" with, or he might not be muzzled. You might also be in a situation where you inadvertently trigger the behavior. My current greyhound has serious food aggression and resource guarding issues. My greyhound would bite, usually without warning, anyone he perceived might be trying to take something away from him. All the members of my family had been bitten because of this, as sometimes it was inadvertently triggered, so it was very important for our safety for him to listen to the "leave it" command. I know some people are hesitant on this method, but I was able to get this behavior under control using a combination of rewards and an e-collar. My e-collar has two settings, shock and vibrate, and goes from level 1-100 in intensity. I removed the shock prongs, and only used the vibration setting, and never above level 5 (out of 100). To give you a frame of reference, this is a fraction of a cellphone vibration ring. Just this gentle vibration was enough for my greyhound to learn not to ignore the "leave it" command. And when he listened successfully to "leave it", I would immediately reward him. Now he knows to listen when we say "leave it", and is also convinced he will be rewarded. No pain or punishment, just a gentle vibration, and now everyone in the house is much more safe. I've also had greyhounds in the past that had the same issue, but to a much lesser degree, and I was able to address the behavior with several training sessions just using rewards as reinforcement. I think it depends on the dog and intensity of the behavior.