Potter is usually very sweet and gentle, though he, of course, has the typical hyperactivity for an almost 6 month old pup. However, when he's given certain (and sometimes random) things, he becomes possessive and snarls and snaps at anyone he perceives as trying to take whatever the thing is from him. He first did this with a Nylabone at 4 months (he has two other nylabones that he's never done this with). He most commonly does this with raw hides. Of all of his behaviors, this is the one I HATE the most, but I really am at a loss as to how to correct it? Any suggestions?