Some dogs tend to get a little aggressive when it comes to guarding their stuff, whether it's food, toys or their personal space.
This negative behavior is called "resource guarding" and you need to teach your dog that this is not acceptable.
Dr. Brad Crauer, medical director at the Seattle Humane Society says you need to teach your pooch to "leave it" on command.
"If they have a toy or something they don't want to share, they're showing aggression, find something that has a higher value, something that they like better. And what that does is that gets them to release the item that you want and exchange that for the thin that's higher value," Crauer said.
Always give that item back. Dr. Crauer says that builds trust.
"Take something away and you just hold on to it, then the likelihood that they'll give it to you again drops. But if you train them where you take it away and give it back, take it away and give it back, then all of a sudden it's not a scary thing for them and they're more likely to give it to you when you really want it down the road," he said.
VetStreet: How to Prevent Food Guarding
VetStreet: How Can I Teach My Dog to Drop a Toy?
About.com: Resource Guarding