Legion mongrel

s are attack dogs used by the Caesar's Legion.

About
Caesar's Legion use them as help in combat. They look like German Shepherds with large manes that help distinguish them from regular dogs. If you are on bad terms with the Legion and wearing Legion armor in an attempt to disguise yourself, a nearby mongrel will sniff you out and turn all nearby Legionaires against you. [CONFIRMED PS3]

Appearances
s appear in Fallout: New Vegas.