Ok, everyone, listen up. Exotic Pets require a 51 point BM build, not only to train them, but to call them to your side as well.
What does this mean if you changed specs? It means you can no longer use this pet, until you change back into BM.

I am absolutely amazed how much I see this question come up.
Exotic pets are for Beast Master Hunters only. I know it made me sad when I changed from BM to MM, as I can no longer use my Spirit Beast pet. I am debating switching back to BM for every except raids, just so I can call her again.