Power Auras + Shadow Infusion

[Knockahontas]

Hi guys.
I have a small problem with my Power Auras, because I can't find a good solution tracking the Shadow Infusion buff on my Pet.
(I am either dumb, blind or it's simply not possible the way I want it)
Right now, I found a solution by setting my pet as the focus target and then make a Power Aura with "Activation by: Buff" and test focus only.
However, I am not really content with this way, because it sucks if you have macros containing /cast [@focus] or such.
Entering the unitname is not an option, because the Dk pet names change everytime you summon it and I really don't want to change my Power Auras after every wipe/respec.
So if someone smarter than me could give me some advice, it would make me somewhat happy.

[Knockahontas]

I feel so dumb now.
But thanks anyways