Have you noticed your dog growling and trying to snap at another dog, at you, or another member of the family when he is approached while eating or playing with a toy?
If so, he's resource guarding - a common behavior in dogs. While resource guarding is prevalent, it's not a behavior to take lightly. Ignoring this problem could result in a dangerous fight between your pets, or even put members of your family at risk.
Why Dogs Guard Resources
It is believed that resource guarding is common because when the ancestors of the domestic dogs lived in the wild, it was an adaptive behavior. Individuals that defended their food from others tended to eat more, live longer, and have more offspring. This propensity to guard food and other resources was passed on to their offspring. While eating their daily meals is no longer a matter of life or death for domesticated dogs, that resource guarding instinct is still alive in certain individuals.
Your first instinct may be to punish your dog to show him that his behavior isn't desirable. But that may lead to more tension, and a worse relationship for you, your dog, and any other dogs in the house. Instead, try to understand the situation and work from there.
Develop a Management Plan
First, evaluate how generalized the situation is. Is your dog always trying to protect resources, or is he just protecting a specific toy or only during meal times? If the fights break out only around mealtime or when a certain toy comes out, a simple management solution may be the answer.
"A suitable management option may be to feed the dogs in separate areas or rooms of your home," explains Lindsay Wood, behaviorist at the Humane Society of Boulder Valley. "If tension occurs only when chewing special chew-bones or playing with a specific toy, the dogs should enjoy their individual toys or bones in separate areas and be reintroduced to one another only after all remnants of the bones have been finished and the toys removed."
If the problem is more generalized or if the intensity of the guarding behavior is high, you may have to consult with a dog behavior expert.