Minecraft should have different types of dogs, and depending on that dog type, it would spawn in a certain biome.
Wolf = snowy biomes
Coyote (Prarie Wolf) = Plains biome or grassy biome
Dingo = Sandy biomes
And in villages, or even surrounding them, would be more house-pet dogs, like beagles, or poodles or something. :P
Its just a thought though :)