First I think we should have a Tamable wolf, or also called a dog. The dog would have several different types listed below
-tracking hound: Preforms track checks for its owner (from my experience this would be very helpful if you are on horseback)
-hunting dog: herds animals towards you so you can attack it.
-pack hound: used to carry items,
-attack dog: can preform a few basic taunts such as coward (growl), and also maybe pounce
Other animals:
Mule: used to carry packs of items, slower than a horse
Coyote: maybe in the desert in the MMO, travels solitary, more damage and health than a wolf