I live in the San Fernando Valley, there was this guy who used to ride around on his HD bagger and his dog "Lady Harley" would just jump onto the tank. He was cited a few times and beat the rap each time.
See the link. Since I do not know how to post pictures into the thread.
http://www.dogsonbikes.com/docs/BikerDogs/LadyHarley/LadyHarley.htm