TIP #1: GIVE-AND-TAKE
You can help prevent resource guarding in a dog who does not display signs of the behavior by teaching him a give-and-take game.
Start by offering him a toy that he likes (but is not extremely valuable to him). When he opens his mouth, say "Take it!" When he does, tell him he's a good boy, then offer him a treat.
When he opens his mouth to take the treat and drops the toy, say "Give," (or "Drop It" or "Trade," or "Share") and let him nibble at the treat while you pick up the toy. The nibbling part is important. If you let him eat the treat and then try to pick up the toy he will race you for it, which may actually encourage resource guarding.
While he is nibbling, slowly and calmly pick up the toy. Let him finish eating the treat, then offer him the toy again and say "Take It!" as he puts his mouth around it.
Practice several times a day, a few repetitions at a time. This game will teach your dog the very useful behavior of "Give" on cue. He will also learn that if he gives something up for you, odds are good that he'll get it back again, or something even better.
- Whole Dog Journal
TIP #2: RESOURCE GUARDING
So what do you do if your dog already resource guards? Although resource guarding may be a natural, normal dog behavior, but it's alarming when your own dog growls - or worse, snaps - at you over his resource. Resist your first impulse to snap back at your dog.
Instead, do this:
Jeff Dentler, CPDT-KA, FFCP, CTDI