I just found this from Wordsmith.org:
running dog (RUN-ing dog) nounA servile follower; lackey.
[From Chinese zougou, from zou (running) + gou (dog), apparently as an allusion to a dog running to follow his or her master's commands. This term was employed in Chinese Communist terminology to refer to someone who was considered subservient to counter-revolutionary interest.]
Well, none of us better try to slip anything past you! Good to know I remembered it correctly. Thanks for the link reference--looks like a good reference source.