While Some dogs have remained domesticated pets, many more have becom wild and hunt the wasteland in packs. The dogs that survived the Great War are a larger, and tougher, breed - now almost wolf-sized. Even so, just as they have in ages past, many dogs have remained faithful and beloved companions to wastelanders. 

Though most breeds of dogs remain largely unaffected by radiation exposure, some modified or mutant varieties do exist. Dogs were also subject to Enclave experiments, which resulted in cyberdogs. However Some pure-breed dogs, such as the yellow dog, also survived, And new breeds emerged, such as the common Wasteland Mutt. But most wild dogs seen around the Wasteland today have become vicious wild cures known as mongrels.

Mongrels are terribly irradiated, mutated forms of dogs. They are red and ghoulish and usually hunt in packs randomly found throughout the wasteland. There are many variants of mongrels, the worst of which are the Feral variants which have become highly aggressive much like Feral ghouls.