This perk affects Bighorner, Coyote, Legion mongrel, Dog, Mole rat, Brahmin, Giant rat and Wolf. It is is also more effective than in Fallout 3, as the second tier of the perk will now cause tamed animals to come to the aid of the Courier, whereas in Fallout 3 the only "neutral" animal type to all factions were Brahmin and no enemies used animals as attack pets.