I have managed to get myself confused again.
I can't quite recall or find the ruling for the following sort of situation:
Assume that the mage Amagus has a Minor Magical Focus in Familiars.
I understand that the focus applies when casting a spell specifically designed to affect Familiars. But what happens if Amagus casts a generic Animal spell on an an animal that happens to be a Familiar?
Which of the 3 applies?
a) gets no Focus bonus, because the spell is not specifically about Familiars.
b) gets the focus bonus only if he knows he is casting on a Familiar.
c) gets the focus bonus whether or not he knows the target is a Familiar.
The above example can change the wording from "Familiar" to "dogs" (both focus and target)