Vicious dog

Vicious Dogs are a nearly hairless species of wasteland canine, ruthless survivors of the wastes, these starving irradiated mutts will attack anything that moves, including you! 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 (aside from Wastelander or Talon Company guard dogs).

Strategy
A Vicious Dog encounter isn't very dangerous, unless the player is already severely wounded, or there's a big pack of them. They have really high Perception, so don't be surprised if they sense you from far away, even if you aren't in their line of sight. They are also surprisingly sneaky, so you might be walking the Capital Wasteland and suddenly get jumped from behind by one. They attack by biting you with various pounce attacks.

After obtaining the Animal Friend perk, they will no longer attack you or your party unless provoked. They can even fight for you after you get the second rank, which can be very helpful as they often run in packs.

Loot
Vicious Dog corpses contain Dog meat, and much as it is today, its hardly worth eating.

Appearances
Vicious Dogs appear only in Fallout 3.