One note may also be helpful for any who do not know the structures
involved, a second note for any who have a ferret with sludge in the
urethra and their vets, and third a link to a useful article if I can
find it and other ref(s):

1. The kidneys (sometime one horseshoe shaped kidney in humans but I
do not know how common that anatomical variation is in ferrets) have a
tube on each side, the ureters, which lead down to the bladder. Ureters
can have problems of their own, problems which was come down into them
from the kidneys, or problems that can be pushed up from a bladder.
Then there is the urinary bladder, and then the tube out is the
urethra.

2. We had two ferrets with cystine uroliths in our decades with ferrets
and the female was easily treated but the male got slush in his urethra
which then blocked. There IS a surgery that is similar to the one done
for male cats in this situation where a new urinary outlet is created,
but our vet first tried repeatedly removing urine from the bladder with
a needle, which our ferret seemed to mind less than the overly full
bladder. It possibly created backwash because the sludge wound up
dislodging and he regained the ability to urinate again after a few
days.

Of course, the problem is that for most ferrets acquired it is not
possible to know if they have the genetic cystine urolith vulnerability
which makes high protein diets and possibly things like peas a risk
factor.

An increase in the rate of cystine stones from ferrets began to be
reported as soon as high protein diets appeared. Such a sudden change
in rate is not going to be because the vulnerability increased. It will
instead be because the previous ferrets were on what for decades was
typical: a 35% protein diet, and that level is low enough that most
ferrets with the vulnerability do not develop stones on it. Our two
lived nicely into senior years with a diet of no more than 35% protein
after their problems in their first years from the COMBINATION of them
being among the ones with the genetic vulnerability and the high
protein diets they were on.

I do NOT know how much cystine (or COLA Group of amino acids which are
building blocks for proteins) might be too much for a ferret without
that genetic vulnerability or if that is even possible, though
everything has an upper limit, sooooooo...

3. <http://www.smallanimalchannel.com/ferrets/ferret-health/bladder-stones.aspx>

The above is a fun and useful read for anyone.

Dr. Osbourne is one of the urolith experts who helped us with our two
ferrets:

QUOTE

J Am Vet Med Assoc. 2013 Apr 15;242(8):1099-103.
doi: 10.2460/javma.242.8.1099.

Epidemiological evaluation of cystine urolithiasis in domestic ferrets
(Mustela putorius furo): 70 cases (1992-2009).

Nwaokorie EE, Osborne CA, Lulich JP, Albasan H.

Source
Minnesota Urolith Center, Veterinary Clinical Sciences Department,
College of Veterinary Medicine, University of Minnesota, Saint Paul,
MN 55108, USA.

Abstract
OBJECTIVE:
To determine the prevalence of cystine uroliths in domestic ferrets
with urolithiasis and determine whether age, breed, sex, reproductive
status, anatomic location, and season are risk factors associated with
cystine urolith formation.
DESIGN:
Retrospective cross-sectional case-control study.
SAMPLE:
Records of 435 ferrets (Mustela putorius furo) with uroliths submitted
for analyses between 1992 and 2009, of which 70 were cystine uroliths.
PROCEDURES:
Specific descriptive information was obtained about each ferret to
determine whether specific risk factors were associated with the
development of cystine uroliths.
RESULTS:
Cystine uroliths comprised 70 of the 435 (16%) uroliths. Cystine
uroliths were more common in male (n = 54) than in female (16) ferrets.
All cystine uroliths were retrieved from the lower portion of the
urinary tract (bladder and urethra [n = 67]) or were voided (3); none
of the uroliths were retrieved from the upper portion of the urinary
tract (kidney and ureters).
CONCLUSIONS AND CLINICAL RELEVANCE:
Awareness of the prevalence of cystine uroliths along with knowledge of
etiologic, demographic, and environmental risk and protective factors
for urolithiasis may facilitate development of surveillance strategies
that result in earlier detection of cystinuria. Genetic factors
associated with this disease have not yet been reported in ferrets, but
a familial pattern of inheritance determined to be a major underlying
factor in cystine urolithiasis in dogs and humans suggests that this
may be a factor in ferrets and that the parent stock of ferrets in the
present study may have been inbred.

PMID: 23547673 [PubMed - indexed for MEDLINE]

END QUOTE

Also look up

Cystinuria

Also, my notes show a paper came out indicating the tetracycline in
some species can cause cystine to precipitate out. In ferrets? Unknown.

Okay, it took a while with many search terms, but after recalling who
posted it here is this for those who need meds for cystine uroliths
specifically:

http://ferrethealth.org/archive/YG13030
Amy and Dave talk about using a med combo successfully for one who
could not be maintained by diet, including:

>She was put on 1.0 ml of Tiopronin 2x/day and 0.5 ml of
>Policitra-K once a day. She had one more surgery several
>months after that to remove a number of stones, and then never
>had another problem with them her whole life. She had periodic
>bloodwork run to make sure the medications did not harm her,
>and she lived to be almost 8. (She ended up with a whole host
>of other things -- cardio, adrenal, abscessed tooth -- at one
>point she was on 5 or 6 meds a day.)

REMEMBER:

Any ferret who gets cystine uroliths is going to be vulnerable to
getting them again because of the genetic vulnerability which is why
their diets always afterward need to be no more than 35% protein, they
need to have their urine pH watched so it does not drop too low, some
need medications, and it is certainly possible that peas -- and some
OTHER foods or food combinations -- might cause similar problems for
this subset of ferrets according to the mechanism in which sulphur aids
the body in changing methionine (another amino acid) into cystine which
is in my last post which was sent to me by a British biochemist.

Sukie (not a vet) Ferrets make the world a game.

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.miamiferret.org/
http://www.ferrethealth.msu.edu/
all ferret topics:
http://listserv.ferretmailinglist.org/archives/ferret-search.html

"All hail the procrastinators for they shall rule the world tomorrow."
(2010, Steve Crandall)

A nation is as free as the least within it.

[Posted in FML 7971]