Imagine what a child would be like if it had only ever been shut in a cage, never went to school, never played or went out: the same is true of dogs. He will be retarded in just about everything he does. Instead of treating him like the pup of 6 months that he is, treat him more like a pup of 8 to 12 weeks, because that is what he is mentally.
He has been deprived of all the stimulation that normal dog owners do as a matter of course: taking the pup out in the fields, playing with it, getting it used to the big wide world and life in general.
I've taken on pups that have been deprived in