
I have serious problems with this attitude from some people that items you have GIVEN your dog still belong to you......
In the dogs mind, anything in HIS mouth is HIS......and quite frankly, id agree......
Thats not to say you dont have the right to ASK for something back, and dogs do need to be taught that when you do ask, they have to give back.
The thing is, most people try to train this with food that THEY have given the dog, when generally the only time you are going to really NEED to take food off the dog is when its found something dangerous, ie bones on a walk, nasty stinky dead things.
Since dogs are SO context specific in their learning ability, any attempts to teach the dog to leave things or give them up by simply snatching food YOU have given them away, are bound to fail...usually with the dog displaying its intense displeasure.
If you want to train your dogs to leave or give up items they have found, then you have to be a bit more crafty than simply taking its dinner bowl away occasionally.
Set up situations with your dog on a long lead, and make sure the item you have 'planted' for the dog to find is less appealing than the treat you will give to reward a 'leave'. Prevent the dog from taking the found item, and reward with the treat. Repeat in LOTS of locations.
Aggression over food that already exists is a different matter, and needs to be treated very carefully. You do NOT want to punish teh dog for warning people off its food, taht will just take away the warning, and NOT the need to do so. Instead reward the dog when people are near its food, set up situations where this is safe, and make sure that from the dogs point of view, he can see that he is being rewarded, do NOT take the bowl away to put more food in, Dogs cannot tell the difference between one cup of food and two.....!
Em