Cite
 

Meaning of working dog

work'ing dog"

Pronunciation: [key]
  1. one of any of several breeds of usually large, powerful dogs originally developed to assist people in their daily work, as draft animals, guard dogs, and guide dogs, and including the boxer, bullmastiff, Doberman pinscher, Great Dane, St. Bernard, and Siberian Husky.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.