The Magickal Role of the Familiar
Apart from being companions and confidantes, your familiar can have a definite place in magickal ritual.
common role played by familiars is as a 'lookout' for magickal
entities, as many animals are far more sensitive to entities than
humans. Cats typically begin watching things and get agitated when an
entity is in the area, snakes also display unusual behaviour.
Obviously, you'd best be familiar with the animal's usual behaviour in
order to notice when it's acting unusually.
The soothing effect animals have on humans can also be taken advantage of in a magickal situation.
terms of more drastic participation in magick, it has been known for
familiar animals to apparently become possessed by an entity, often one
that appears in the form of that animal.