Actually, I'm still leveling my character up and managed to get the pup. All I did was participate in a few Invasions to get Nethershards, and just outside the town you kill the last boss in there's usually a camp with a Captive Wormtongue. As it's mentioned in this guide, you only need to do the questlines to see them in the main cities (Orgrimar and Stormwind), but outside these cities you'd see them just fine. :3
1102 pets
Actually, I'm still leveling my character up and managed to get the pup. All I did was participate in a few Invasions to get Nethershards, and just outside the town you kill the last boss in there's usually a camp with a Captive Wormtongue. As it's mentioned in this guide, you only need to do the questlines to see them in the main cities (Orgrimar and Stormwind), but outside these cities you'd see them just fine. :3