All living things have an aura, a kind of energy field that surrounds us and is generated by our 'life energy'. It is somewhat similar to what spiritualists call ethereal body because it exists on a different vibratory level than the physical body.

An aura shift occurs when someone believes or feels this energy field has changed shape to that of their were animal. Most people outside are able to sense an aura shift when it occurs, feeling some sort of dread or fear for the shifter.