'Death' of a familiar

What happens when a familiar gets into a situation that would be fatal to a normal animal? I know familiars are bits of magic that have taken a form so they can't die in the traditional sense, but struck by a car, shot from the sky, torn to bits by a velociraptor or what ever can't be healthy for them.

I think it depends a bit on how the familiar is maintaining its form. The three likely possibilities are a coherent energy field, manifested ectoplasm or an actual physical body.
Each has advantages and disadvantages.
The energy field is least likely to be damaged.
Ectoplasm can be damaged, how long it takes the mage to reform it is a variable.
Physical bodies obviously take damage depending on how tough they are, and may or may not regenerate