My sister-in-law forms these type stones and my wife is an RD.  I'll stick
my neck out and relate what she has said.  These stones are a result of poor
protein digestion (genetic).  This causes real problems for your high
protein needing ferret.  In people, one treatment is to give sodium bicarb.
to make the urine more alkaline and slow down precipitation.  This has
implications for the heartbeat, so discuss with your vet.  (They also go on
a low protein diet, which you might also want to discuss variations of.)
 
Another thing is that the stones in the bladder are just chips from the
BIG ones in the kidneys.  You might want to get X-rays of the kidneys,
because that is where the real problem is. The whole kidney can be
destroyed.   My sister-in-law lost one kidney from this and has had several
operations on the other.  They have a new treatment at Mass. General that
involves ultrasonic waves in a water tank.  This busts the rocks up and
allows them to be passed.  It's still experimental, so there may not be a
veterinary equivalent.  The bicarb. may be one way to go though.   It is a
very tough problem, good luck.
 
   ( )--(a)
   (@=@=) \     Till next time.......Rudy the ferlosopher
   O__)  \ \___
      \   \
      /\ * )  \
[Posted in FML issue 1257]