Possessive behaviour in dogs can be dangerous, so it is important to recognise and treat it as early as possible.

Some dogs will 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.

'Possessive aggression' or 'Resource guarding behaviour' 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 dogs of both sexes. However, although some dogs that exhibit aggression will have a history of being possessive as puppies, not all possessive puppies grow up to be aggressive.

As with other categories of aggressive behaviour, possessive aggression can lead to serious bites. Puppies must therefore 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.

You can also prevent food guarding by training your pup to approach during eating. Place half of his food in his bowl, then add more food as he is eating. He will associate human approach with a positive result - more food.

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.

Ensure you have your dog's respect by asking for commands to be obeyed prior to receiving any food, treats, toys, walks or attention.

It is vital to bear in mind that aggressiveness, regardless of motivation, cannot be cured, only controlled. If your dog has ever growled, snapped or bitten, ask your vet to refer you to an animal behaviourist.