Been on second life for a while, and I found that the majority of TF material (if you can call it that) is mainly Furry based. Not gonna poke fun at it as end of the day, whatever floats your boat (and this is a fetish forum). But the furry stuff isnt for me.
However, you can now buy a complete Lycan avatar (called the Wolfkin) that is large and semi monsterous, whilst keeping the look and general style fairly realistic. What's even better, is there is a Female version as well!
And here is the Male version for reference...
The big issue though is the transformation itself. I believe it is possible for someone to develop and sell a transformation animation to use in SL, but so far noone seems to have attempted it. Huge shame as the TF possibilities are truly ENDLESS