The rats are living off of Henry's poop

Henry is the pitbull next door. His owner complains to us every time we see her about rats in their building and yard. I looked up a few things about rats in urban areas and learned that rats eat dog poop. Something plentiful in their small yard. Poor Henry has never been walked in the 6 years he's lived here. I doubt he even has a leash. He a sweet dog. Its so sad.