Resource guarding is a common form of aggression in dogs. The dog protects valuable resources such as food, toys, treats, furniture, blankets, other dogs and even people. For this reason it is also known as possessive aggression. The dog protects its possessions with a growl or stare. If the warning is ignored, they may escalate to biting.
Prevention is the key to dealing with this form of aggression. Feed the possessive dog in a separate room or kennel to make sure they can eat in peace. Give them tiny treats that are eaten in one bite without the need to protect leftovers from others. Separate them for treats like chew sticks that take longer to eat. I do not recommend removing the food or treat from the dog once it has been served. In my experience, this makes the dog’s aggression even worse. For serious cases, I recommend putting the dog outside while their food is prepared. Place the bowl in the room or crate, remove all the other animals or people from the immediate area, let the dog in and then close the door behind them. Do not disturb them until they let you know they are finished licking the bowl. Put them back outside and put the bowl away.
For dogs who protect toys, blankets or dog beds, I would remove the object to prevent aggression. Bring out the toy for individual play time and then put it away again before encountering other dogs. If the possessive dog sleeps on the bed with its favorite human and growls at other family members, ban the dog from the bed.
In my experience, dogs can never be “cured” of resource guarding. This behavior may be lessened but I would always be cautious in situations that may stimulate resource guarding. Use extreme caution with young children!