This is part of the Outer Mystery of House Bjornear, the Heartbeast.
But that got me thinking, how would you go about doing that anyway?
Or more generally, if something (or someone) has been transmuted into something with a different shape/form (and possibly even Form), how would you go about discerning the original shape, with Hermetic magic? I suppose Second Sight would do the trick, but that's not exactly Hermetic.
Please note, I'm not worried about finding out that an object has been tranformed - InVi can tell me that something is affected by Muto magics - but how do I find out what this object was before it was transformed?
You can't tell Bjornaer's animal shape from their human shape with Hermetic magic, full stop.
I doubt very much that any magic can distinguish a heartshape from a human shape directly. This should also be difficult for Faeries, and possibly demons. The Divine, of course, can tell; likely the soul is the standout feature observed by Divine beings (God, saints, angels) and a Bjornaer in animal shape still has a soul.
You can detect the Gift, though, with InVi. The heartbeast should show this just the same as the human shape. I'm not aware of any animal ever having the Gift. You still couldn't tell what the animal looks like in human form.
Well, you might start with the InCo General spell Sight of the True Form from page 130 the core book and (modify and/or add) (spell and/or casting) requisites as dictated by the beginning/final form's Forms?