Looking for a movie I saw here 30 years ago?

It starts out with a family trying to survive a nuclear war  fast forward a man dressed as a dog and the family let him live under the house and he acts like a dog running people off. The father tries to make him stand up telling him he is a man at no avail.  

 Fast forward to the end, the family was starving and the boy says people in the east eat dogs. The father gets his gun and the family argues no its a man the father said no its a dog as he goes out to kill the day the movie ends. 

 I would love to see it again or possibly downloaded for my collection