The puppy in question was rescued at four weeks from a young lady who found him, his mother and siblings abandoned in an apartment. She bottle raised the pup for a month because the mother would not nurse. She said she could no longer afford the milk and needed to find him a new home. I agreed to take the pup and at 8 weeks I gave him to my friend who fell in love with him. At 13 weeks he started developing aggression towards my friend when she scolded him verbally for having accidents, and started growling and biting as she would reach into his crate for the soiled towel, and outside if the crate when he had an accident that she did not know about. He was always a pleasant pup, and I have never experienced this before. She has given up and given him back to me. He was fine the first day, but today he displayed the same aggression to me, and I didn't even know he had an accident. He turned into a completely wild animal. He growls, will not allow you to touch him and will bite and draw blood. Does anyone know how one should handle this? Obviously it is best to prevent the accident in the first place since it triggers this fearful aggression, but how should this behavior be treated? He is exactly 12 weeks old now.
There are many types of aggression and for your dog it could defensive, social or possessive aggression. For all of this, you must learn to become leader and master for him. One thing you can start with his food, put the bowl near to him and command stop while standing your ground, just let him reach it when you see he is submissive to you. This way he can learn you are the master and you can gradually increase the time before he can eat. Socializing and exercising him also helps a lot on behavior.