Sudden food guarding is a perfectly normal behavior in dogs. Instinct is telling your dog to protect his resources. That’s not to say it’s a nice behavior or that you can’t teach him some table manners. The trick is to help your dog learn that nobody wants to steal his food.
Behavioral Causes
A dog may be naturally food-protective from puppyhood, as some dogs simply have strong survival instincts and the dominant traits to assert them. This behavior is most likely to develop gradually, although it may seem sudden to you the first time you accidentally go too close when he’s chowing down.
Environmental Causes
He may develop the behavior in response to his environment. For example, if other dogs are constantly sticking their faces in his food bowl, he’ll learn to protect his food with warning growls. Once learned, this behavior becomes a habit and anyone approaching him while he is eating may be met with a rude “go away.” If a previously well-mannered dog is suddenly growling and protective over food, it is most likely due to a recent experience, such as being disturbed while eating, having his bowl removed before he is finished, or having another dog try to steal his food. A new dog joining the family is a classic trigger for sudden food guarding.
Other Causes
Medical conditions cause food aggression. For example, if he has dental or gum problems, eating will cause him pain. The pain of eating will cause stress, which will raise the likelihood of your dog becoming aggressive or growling when approached. Pain-related food aggression typically occurs suddenly. Hunger can also be an aggravating factor too. If you were late back from work, for example, and your dog hasn’t been fed, hunger may be a new sensation to him. If you then go near him as he’s wolfing his food down, the chances of him being protective are higher than if he wasn't hungry.
Associated Behaviors
Resource guarding doesn’t just apply to food. You may notice your dog being protective over his toys, his sleeping area and even you. Dogs who guard their resources are typically territorial by nature, so barking at visitors is a strongly associated behavior. As dogs mature, their behavior changes. A previously playful puppy may quickly turn into a grouchy teenager who hates visitors and freaks out when people go near his bowl.
Fixes
The best way to cut out this behavior is to help your dog learn that his food source isn’t under threat. If there is another dog in the house, feed them separately and don’t let either approach the other until both have finished eating. Never remove your dog’s food bowl while he is still near it, even if it’s empty. Wait for him to wander off.
