I\'ve always thought that familiars and pets should be kept separate. A familiar is a creature that is bonded to you (provided you take care of it) and is as much a part of your being as your character.
Pets, however, should be animals that are either caught in the wild or bred from other animals. It is the job of an animal trainer to charm, capture, domesticate, care for, train, and sell animals. These pets can be used for various things, depending on what they\'re trained to do. You could have a pet that would alarm you when dange was near, carry extra gear for you, or just be a deadly weapon. But they are still just animals.
A familiar is more of a magical being; you use a bit of your blood and some magic to summon your familiar. This required you to be magically inclined, and it is your creature; it cannot be sold or traded. Although animals will most likely have skills, familiars will be more magically oriented, to the point that they can even cast their own spells (if you have a caster type familiar, that is).
Just my opinion, of course