>My 8 month old jill has just had her right kidney removed.  I posted
>here yesterday, but had little response.  I am trying to find any info on
>cystic kidneys in ferrets.  What is the most common cause likely to be in
>such a young ferret?
 
Dear Carol:
 
In an 8-month-old ferret with cysts only on one side, there are two
possible causes.  The first, and most common, is a congenital defect.
These are extremely common in ferrets, and we see cysts 25% or so of
ferrets at necropsy (for other reasons.) Perhaps someone one day will do
a study - this would be relatively easy to quantitate with ultrasound -
they are usually of a size that they would jump out at you.
 
The second reason, and the more likely reason for a kidney to be removed
is that we are not dealing with a true cystic kidney, but a case of
unilateral hydronephrosis.  Hydronephrosis occurs when the outflow of
urine is blocked from one of the kidneys.  In the ferret, the most common
cause is a urinary tract infection which ascends from the bladder up the
ureter (the pipe that connects the kidney to the bladder.) If inflammatory
debris blocks the outflow of urine, the pressure will build up in the
ureter and back up into the kidney.  That kidney is going to continue to
make urine - it doesn't know that the plumbing is blocked.
 
As the pressure builds up in the kidney, the kidney tissue eventually
withers away under it, and eventually, you are left with a large bag full
of urine.
 
The third possibility which is very remote would be true polycystic kidney
disease, a rare genetic defect of ferrets in which all of the plumbing is
malformed, and many large cysts develop, eventually resulting in renal
failure.  But that is extremely rare in this species.
 
With kindest regards,
Bruce Williams, DVM
[Posted in FML issue 3711]