Hello ! Days ago some blue tweeted about a project "Tiny Cow" (Jeremy Feasel and Jonathan Lecraft who usually show some new pet) :
In the last beta build, it appeared to be linked with a battle pet since there was some battle pets ability related to cow :
Udder Destruction: 100% Hit Chance
Deals 30 Beast damage and has a 25% chance to stun the target.
Where's the Beef?: Increases your chance to dodge an attack by 100%.
Lasts 1 rounds.
Mother's Milk: Heal other friendly pets, restoring 24 health to each.
I wish but no, theres a darkmoon faire trainer who has a tiny cow for a pet, thats probably where its coming from.
Besides the tauren chieftain would probably have music related skills, like the one from heroes of the storm.