As I'm sure you know, worgen are classified as a humanoid. However, one wolf in Howling Fjord, Garwal, is a wolf that turns into a worgen at ~55%. Also, you need the quest Alpha Worg to see him.
If you tame Garwal as he is turning into a worgen, or a little bit beforehand, he will transform into a worgen as you tame him, keeping his worgen form.
Garwal will stay this way as long as you have him. Happy hunting! :wave:
Edit: Worgen Pet. This is not me in the pic, btw, it is someone else who has the worgen pet.