In the U.S.  ferret foods tend to be well controlled to not cause the pH
of urine to become too alkaline.  The presence of crystals in urine here
is more commonly a side effect of adrenal neoplasia.  It would pay to
test the urine's pH first and follow vets' advise below.  Ferrets aren't
cats and this is one of the differences.  If you look in
http://www.smartgroups.com/vault/ferrethealth/prostate.txt
you'll find info on this from some ferret specialist vets
 
For examplel from Dr. Bruce Williams:
>A common cause of dysuria in male ferrets is adrenal disease - the
>liberation of estrogens cause swelling of the prostate, which impedes
>urine flow. It first manifests as straining, and later becomes total
>blockage, with is life-threatening.
 
>In these cases, ultrasound is a good diagnostic test, if the vet knows
>where to look for the prostate. In normal males, it is not easily found -
>in ferrets with cystic prostatic disease, it shows up fairly readily.
 
>It will also show bladder stones fairly well also. It would be my
>preference, if available, over an X-ray.
 
>Difficulty urinating can be life-threatening, and warrants a complete
>workup.
 
and
 
>The most common cause of dysuria in male ferrets is prostatic disease as
>a result of adrenal disease. Our belief for many years that crystals in
>the urine was causing these animals not to be able to urinate was simply
>incorrect. Crystalluria (sandy crystals and plugs in the urine) do
>occasionally happen, but nowhere as commonly as adrenal disease will
>cause this problem.
 
>With adrenal disease, the estrogens result in the prostate swelling and
>occluding the urethra as it passes through. These animals cannot
>voluntarily urinate, but the bladder is easily expressed.
 
>Differentiation of the two syndromes can be accomplished by one or more
>of the following tests:
...
 
>3) Do a urinalysis, to include a sediment exam. While both causes will
>result in WBC's in the urine, there are usually far more in prostatic
>disease, as there is often suppurative inflammation coming out of the
>bladder.  The sediment in prostatic disease will have numerous white
>blood cells, and flakes of keratin.  In urinary stones, you will see many
>urine.  The pH of urine in crystalluria is usually more alkaline.
 
From Dr. Jerry Murray:
>I'll have to second Dr Williams' post. Prostate problems are common in
>male ferrets with adrenal gland disease!
>If your male is on a good food then he should not be having crystals or
>stones.  If he is also showing adrenal gland signs (thin haircoat, hair
>that epilates easy, increased musky odor, itchy skin, orange tinge to
>the skin in the shoulder blades area, return of sexual behavior,
>aggressive behavior) then it is time to treat him for the adrenal gland
>disease (surgery if he is healthy, Lupron and Propecia if he is
>unhealthy).  A PU surgery will NOT help with a prostate problem!
 
There are more...
[Posted in FML issue 3997]