It's kind of hard to tell what happened so I'm not sure if I would jump to any conlucisions. It seems like when the police first found the man and tried to help him he was fully clothed. It doesn't mention him being naked until after they tracked him down because he ran away. The clothes didn't come off until after he ran away, and they said that when he was first found he was disoriented. While I think he may have done something wrong to upset the dog, I'm not sure that it beatiality since he wasn't naked until after everything happened.