Dogs are only transported by the HVV under the supervision of a suitable person. The transport of dangerous dogs (...) (Pitbull Terrier, American Staffordshire Terrier, Staffordshire Bullterrier, Bullterrier as well as their crossings among themselves or with other dogs) is forbidden. Dogs suspected of being dangerous (...) and other dogs that could endanger fellow passengers must wear a muzzle. Dogs must always be kept on a leash. They are to be led in a way that annoyances and endangerments of other passengers are prevented.