By Denny Dyroff, Entertainment Editor, The Times  National Dog Show If you suffer from cynophobia then don’t even think about visiting the Greater Philadelphia Expo Center (100 Station Ave., Oaks, 484-754-3976, http://www.phillyexpocenter.com) this weekend. Cynophobia is the fear of dogs. On November 19 and 20, the National Dog Show will be held at the Greater Philadelphia Expo Center – from 8...