Do you remember hearing that? Your mother/aunt/father had a good point. A lot of dogs have a problem with possession aggression. In other words, "what's mine is mine, and you aren't allowed to even look at it." Sharing is a foreign concept to most dogs, especially dogs who are the sole family pet. A dog with possession aggression will guard his resources, whether his resources are his food, toys, or the most valuable of all, You.
Oops, you've left it too long, or you've adopted a dog who's got guarding tendencies. Either way, it will now take time, patience and persistence for your dog to learn that there's no need, and that it's unnacceptable to try and protect his food.
Grab yourself a handful of treats. These should be the regular "oh these are so good, I love them" treats, but not the drool-worthy uber-motivating treats like chunks of cheese, or liver biscotti. Not yet.
Well that's a no-brainer. What is better to have? A tasty treat, or a stick? As soon as that stick is let go, give him praise and treats!
Don't stop there. Keep it up! He needs to cement in his mind that when you, the ultimate Boss, come by, you'll remove whatever he has, but you might replace it with something better.
Don't give it to him.
Or at least, not yet. Is he giving you pleading looks yet? Is he sucking in his belly to produce that emaciated look, and adopting the saddened hound-dog eyes? Okay then, now it is time.
You follow the new routine, making him go through a bit of a hassle before he gets his full dinner again, but this time, instead of leaving him to eat in peace after, you put your hand on his head, and follow his movements, keeping it in place. Does he give you dirty looks, but continue eating anyway? This is good. Move your hand, just stroking his head. This in itself is a reward activity, but it may take him some time to realize that it's okay, you aren't going to steal his dinner away for good.
Once he's used to you petting him while he's eating, and he's relaxed in your company, the next step is to remove his dinner. That's right. Do what he's been afraid you'll do, right from the beginning. Take it, and turn your back on him. Put one of those drool-worthy treats I mentioned earlier right on top of his dinner, then give it back. Aha. See? Like "Trade", but you didn't give the command. Keep it up.
By using patience and persistence, rewarding the good behavior, and employing the "work for it" rules, you can turn your resource guarding dog into a dog you can pet while he's eating. Just remember ... just because you can, doesn't mean you should. Everybody deserves to eat in peace.
Mine! A Practical Guide To Resource Guarding In Dogs