Sorry that your ferret has experienced those, Kristen. We have two who
get them and ours are fine as long as they are on a diet of no more
than 35% protein. These individuals can not safely eat the high protein
diets on which others may thrive.

Some require meds. Info on those is in the FHL Archives. Both Dr. Mike
Dutton and Dr. Tom Kawasaki have treated such individuals, but that
was a while ago:

http://ferrethealth.org/archive/YG13030
etc

Cystine stones are caused by individuals having kidneys which can not
cope well with any of four specific amino acids: Cystine, Ornithine,
Lysine, or Arginine. Then the cystine winds up precipitating out. There
are multiple genetic routes to having that problem, though for a long
time only one was documented.

Studies have already indicated that the pea component should not be the
problem for several reasons: it is too low in those amino acids, and
peas also contain compounds which reduce amino acid uptake (which is a
way that seeds protect themselves when they pass through the gut of an
animal which ate them and then emerge in a pile of nutrients). (pers.
coms. with two experts in different inquiries)

On the other hand, those protein sources may simply be too high in
those amino acids for vulnerable ferrets.

Cystine uroliths in ferrets are a study subject of a group headed by
Dr. Michelle Hawkins at UC Davis who noticed the number of cystine
stones found in ferrets to be rising. (Of course, that may reflect
vulnerable animals showing up due to the increase in numbers of high
protein foods, but it could mark a change in genetic rates.)

It is useful to periodically x-ray the bladders of these individuals
to make sure the problem doesn't begin again, and to use urine pH test
strips to make sure the urine does not stay or again become too acidic.

(Struvite uroliths have the opposite scenario, and there are other
forms of bladder stones, for example calcium oxalate ones, Baytril ones
(rare but if huge doses are given it has been documented precipitating
out in the urinary tract), etc.)

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5807]