Urine marking:
My experience; Boo-Boo was a found ferret that I'd adopted from our
shelter.  Very aggressive to my other ferts.  I knew nothing of his
background, so attributed this to never being around other ferts (he's a
DEW and deaf).  He also marked.  We started to suspect an adrenal tumor but
it was still too early to tell.  Several months later he started itching
and developed "papery" looking skin and it looked like his skin had tiny
scratches.  In he went for surgery, and yes, his adrenal was bad.  He
never developed the other more "classic" adrenal symptoms, maybe if it
had progressed further he would have.  From what I've gathered, marking is
probably a common symptom that just hasn't gotten much discussion.  The
vets I'd spoken to weren't quite sure what to make of it.  Watch out for
urine burns!
 
I'm not saying this is the cause of your ferrets' marking, but it should be
considered as a possibility.
 
Dish digging:
Great fun for them but not for us.  Mine seemed to get bored with this
game as they aged, though some will persist.  Water dishes aren't the only
victim, food dishes are just as much fun.
 
Try getting some "crock-lock" dishes, or any type of dish that will
securely attach to the side of the cage.  Fix it low enough that they can
still eat and drink, but high enough that it's uncomfortable and awkward
for them to get their paws into.
 
Hope this helps!
SP
[Posted in FML issue 2591]