I'm not surprised. They can get big, they are strong, and they can be mean as hell. And the ones that live in and around cities and people are not afraid of anyone. And most dogs, even a big one, would not stand up well against a full grown raccoon.
I had a friend who grew up on a farm. She had a dog, an Australian Blue Heeler, or Shepherd, or something, some type of working, farm dog. Her dad watched the dog chase a raccoon down the hill into a small stream that flowed thru their property. ONce in the water, the raccoon turned and attacked the dog, and sat on his head and held him underwater and tried to drown him. If her dad hadn't chased the raccoon away, the dog would have been drowned. Raccoons can be scary smart.