There are many types and styles of harnesses suitable for vehicular travel. One potential issue with dogs who are elderly or particularly large is the chance that as a vehicle stops short, or spins in the midst of an accident, the harness itself can actually fracture the sternum or cause neck or body damage to the dog if it is improperly fitted. Obviously, if the dog were not restrained at all he would most likely be killed or critically wounded, so drive safely and purchase the correct harness. Purchase a good quality harness that fits well and is heavily padded against the chest and neck.
