working dog - any of several breeds of usually large powerful dogs bred to work as draft animals and guard and guide dogs

kuvasz - long-established Hungarian breed of tall light-footed but sturdy white dog; used also as a hunting dog

attack dog - a watchdog trained to attack on command

housedog - a dog trained to guard a house

schipperke - breed of small stocky black dogs originally used as watchdogs on boats in the Netherlands and Belgium

pinscher - any of three breeds of dogs whose ears and tail are usually cropped