#0 - Nov. 7, 2009, 2:54 a.m.
Blizzard Post
We will be making a change to the Pet Store such that pets purchased from the online store can only be claimed with World of Warcraft accounts registered to the region from which the purchase was made. In order to claim a pet from our Pet Store, your account must be registered to the same region as the store from which you purchased the pet. Players who have already purchased a pet from a store in one region and redeemed it on an account in a different region will remain unaffected by this change. Players on U.S. realms can access the U.S. Pet Store here: http://us.blizzard.com/store/

Original post can be found here: