I think I would go about the positive re-enforcement method instead of the negative(i.e. coin in can).
More than likely he is not growling because he is mean, more than likely he is scared. I think you need to teach him that strange people are okay. Take the puppy out more often. Let people pet him and give him treats or even hold him(after he is confortable with the first two). Teach him there is nothing to be scared of. |