Chain Chomp

Bow-Wow is a version of the Chain Chomp from Super Mario Bros. It is found as an enemy in A Link To The Past, as an ally in Link's Awakening, and as both an ally and enemy in Four Swords.

A Link To The Past
In A Link to the Past, Bow-Wows can be found as enemies in certain Dark World dungeons.

Link's Awakening
In Link's Awakening, Madam MeowMeow is the owner of a docile Bow-Wow. Both Bow-Wow and her owner live in Mabe Village. After completing the Tail Cave dungeon, Bow-Bow is kidnapped by a gang of Moblins. Link rescues her and brings her back to MeowMeow... who then asks him to take her pet on a walk. Bow-Wow can then be used to eat the otherwise-impenetrable Goponga Flowers blocking the entrance to the game's second dungeon, Bottle Grotto.

Although Bow-Wow can take care of most enemies for Link, she cannot be taken into dungeons.

In Link's Awakening DX, a picture can be taken with Bow-Wow.