Well....a dog might be doing that because he/she is feeling not cared for or unloved. When animals feel a certain type of anger towards you or your house(furniture, etc.)it is usually regarding something that the owner has done to anger them or make them feel uncared for. You have your dog on a chain? He is probably feeling not cared for, and since he knows your the one that chained him, he expresses his anger towards you. Trying letting him off his chain once in awhile and letting him inside. Give him lots of treats and TLC to make sure he knows you love him.