They are spirits, NOT ever your pets.
Please note, this means not your currently alive pets – as in pets you currently have. While pets that have passed on, do sometimes become familiars after passing, this is uncommon.
They are also , more often then not, not companion animals/creatures.
also, while pets do sometimes get interested in our magical workings, they are not and should not be considered your familiar.
Familiars are spirit companions, who are either creatures or animals, who act as either guardians or partners/teachers in your magical workings/path.
You can note what they’ve brought into your life, when they entered/exited, and what they’ve taught you.