Britain 's Mark Cavendish claims second win of this year 's Tour . Team Sky 's Bradley Wiggins maintains overall lead . Dog on the course cause four-bike crash . Comment:
Britain 's Mark Cavendish claims second win of this year 's Tour . Team Sky 's Bradley Wiggins maintains overall lead . Dog on the course cause four-bike crash . Franck Schleck announces failed ' B ' sample , pleads innocence .