Vicious dog

Vicious dogs are a nearly hairless species of wasteland canine, apparently Pitbulls. In Fallout 3 they replace both wild and mutant dogs of the previous Fallout games as one of the only hostile canines a player will encounter.

Compared to other animals such as bears and cows, dogs have been relatively unaffected by the Wasteland's radiation (as can be seen by the lack of mutated canines).

Vicious dog
Ruthless survivors of the Wastes, these starving irradiated mutts will attack anything that moves, including you, unless you have acquired the Animal Friend perk. Sometimes they hunt in packs.

Raider guard dog
This is a vicious dog that fights alongside its masters, raiders; they are still affected by the Animal Friend perk.

Talon Company guard dog
These dogs will often be accompanied by their masters, none other than the infamous Talon Company mercenaries, but are still affected by the Animal Friend perk, much like their raider brethren.

Guard Dog (Operation: Anchorage)
Used as guards by the Chinese soldiers in the Anchorage Reclamation simulation, and are unaffected by the Animal Friend perk, unlike raider and Talon Company guard dogs. Guard dogs are worth only 1 XP. They are identical to Dogmeat in appearance, even having the same eye color, one being blue and the other green.

Loot

 * All vicious dog corpses will only contain dog meat.

Appearances
Vicious dogs appear only in Fallout 3.