Dead Age

German Shepherds aren't (usually) found as part of area combat, but appear either as negative consequences of encounters, as part of camp assaults, or as part of the Desert Day area. mixed in with Punk attacks. Because German Shepherds are quite uncommon when fighting Punks, and the fact you may not naturally see many during the course of the game, leads the German Shepherds achievements being one of the two easily missed categories of "kill" achievements in the game (the other one being Soldiers).

Fortunately, there is a workaround for this problem that you can use in the Desert Day area only (which you visit around Day 35).

Farming German Shepherds

Start up your Day 35 quest, entitled "A New Hope", and after a series of mishaps, you'll be automatically teleported to Desert Day. Your first two encounters should have one to two German Shepherds each. Kill them. Now, quit to menu and restart the Day, starting up the Day 35 quest again. While not tracked in game, your previous kills will track for the German Shephard achievements within the Xbox tracker so keep going through the first two areas, killing German Shepherds, then reloading the Day, until both German Shephard achievements unlock. Once done, feel free to continue the quest.

German Shepherd Stats
Fast: Yes
Immune to K.O./Stun: No
High Defense (aka needs Breakthrough): No
Special Abilities: Animal Sense (Buff), Blitz Attack (Buff)
Priority Targeting Level (1 - 8, 1 is max, 8 is min): 8
Locations: Desert Day, Camp Attacks, Failed encounters