Dogs will usually compete with other dogs, as well as with their human family - for attention, favourite chairs, toys, and access to food. Life in a social group has its advantages, of course, but it can also increase stress when some items or activities are particularly coveted or rare. Most dogs appear to recognise limits and will defer to members of their human family. But in some cases, they will threaten anyone who stands in the way by growling or even biting.
Recognising possessive behaviour
'Possessive aggression' is the term used to describe threatening behaviour - staring, 'standing over', growling, snarling, snapping or biting - when it is associated with food, toys, or other items in the dog's possession. Unlike dominance-related aggression, which usually appears for the first time in young adults (more often than not in males), possessive aggression can be seen in puppies or dogs of both sexes. Although some dogs that exhibit dominance aggression will have a history of possessiveness as puppies, not all possessive puppies will grow up aggressive.
What can you do about it?
As with other categories of aggressive behaviour, possessive aggression can lead to serious bites. Puppies must be taught that such behaviour is inappropriate. One effective method used by trainers is to teach your puppy to drop items on command - starting with less interesting objects, and rewarding the drop (followed, ideally, by moving away from the item and sitting down) with an enticing treat. Prevention is also wise - especially in households with children. For example, dogs that get particularly stressed about being approached during meals should be separated when fed, and those that growl or bite when they are chewing or playing with toys should not have access to toys unless separated from others.
Control is the key
Most important is to bear in mind that aggressiveness, regardless of motivation, cannot be 'cured' but only controlled. If your dog has growled, snapped, or bitten, ask your vet to refer you to an animal behaviourist.