No, that's being based on In-game dialogue that goes as follows:

Red XIII: Please stop, grandfather. I'm 48.
Bugenhagen: Ho Ho Hoooo. Nanaki's tribe has incredible longevity. So you see his 48 years would only be equivalent to say that of a 15 or 16 years old in human reckoning.
Cloud: 15 or 16!?
Bugenhagen: He's quiet and very deep. You thought he was an adult?

And he is rather wolf-like in both appearance and behavior (as in howling at the moon).