While this article was written to address dogs that have already demonstrated aggressive behavior, the pointers should be followed by anyone who owns a guard breed such as the bullmastiff to prevent signs of aggression from occurring.
Aggression: 15 tips for taming your dog
These tips will help you establish yourself as a pack leader in a positive way over your aggressive dog:
Do not play games such as tug-of-war unless you always win. This game is initiating a physical contest and the Alpha must always win.
Do not let your dog keep the toy when you are playing; they need to learn to release and drop the toy. Toys belong to you (the Alpha) not to your dog.
Do not let your dog show its teeth, touch its teeth on your skin or growl during play. If they do, stop playing and take the toy away.
Do not play catch or chase games with toys that will be hard to take out of your dogs' mouth. As the Alpha, you cannot risk the possibility of not being able to take possession of a toy that belongs to you.
Do not let your dog demand attention. The Alpha chooses when and how often their pack members are touched and groomed. So ignore your dog when they are demanding attention or simply give the "down" command.
Do not feed your dog before you eat. Alphas always eat first. So eat first and then feed your dog and don't give them table scraps while you eat.
Do not let your dog on the sofa and bed. A higher ranking dog always chooses the best sleeping area and it's usually higher than all other pack members.
Do not let your dog go through narrow spaces such as doorways first. Make sure that you, the pack leader, have this privilege.
Do not let your dog have free range of your entire house. Claim a room as yours. This room/territory is yours unless you invite the dog in.
Do not let your dog block your path. If your dog is lying in the way or blocking your path, gently tell him to move.
Do not let your dog put its paws on you and elevate himself. A higher ranking member will always try to raise their body above a lower ranking member.
Do not be inconsistent. Dogs are always looking for signs of weakness to show their strength.
Do not limit these rules to one location. Make sure wherever you are your dog knows the boundaries.
Do not let family members sabotage your hard work. Every member of the family needs to follow the rules so that your dog knows it is the lowest member in the pack.