Message Number: FHL12301 | New FHL Archives Search
From: Sukie Crandall
Date: 2010-10-04 15:58:26 UTC
Subject: [ferrethealth] for people who don't know the different types of uroliths
To: Ferret Mailing List <ferret-l@LISTSERV.FERRETMAILINGLIST.ORG>, fhl <>

Kidney stones/bladder stones/urinary tract stones/uroliths come in
many types. They have been mentioned without details in recent FML
posts so I figured this might help some people in time to save some
ferrets, and will copy the FHL.

The ones that Hilbert used to get and which Morney has gotten in the
past are cystine uroliths. Cystine stones have a few genetic causes
found in other animals but the specific genetic cause(s) in ferrets
has/have not been reported upon yet in a veterinary journal. These
are not the uroliths people most commonly read about, but are not
terribly rare in ferrets, either. For this type of urolith the person
who is feeding the ferret needs to reduce 4 of the amino acids
(cystine, ornithine, lysine, and arginine) so the best approach for
them without taking protein below safe levels is to reduce protein
intake to about 35% of the diet. A very rare few need medications but
careful dietary management can be sufficient. This problem is
typically found when a susceptible individual goes onto a higher
protein diet than his or her kidneys can handle. With these stones
the urine will be too acidic. In these ferrets you want the urine pH
to be higher than 5, preferably about 6 which is ferret-normal for
urine pH. Once stabilized these ferrets need to have their urine pH
monitored and to have periodic bladder x-rays to check for any
possible new stone formation though a careful diet definitely can life-
long and does perfectly from our experience with long lives possible.
The trick is surviving that first crisis but that is incredibly
difficult and sadly not always possible.

Many uroliths -- of ANY type -- in male ferrets wind up being fatal
right from the start. That is because many are not found until a
ferret completely blocks or develops hydronephrosis, and mostly
because male ferrets block much more easily than females and are
harder to treat. Surgery is often needed to correct the problem even
though the ferret is often compromised when the problem is
discovered. Also, a more extreme surgery, rerouting the urinary
outflow can be needed at times if the male has a blockage in the
urethra and if repeated cystos (removal of urine by needle) are not
sufficient to let the sludge dislodge and in the inflammation go
down. The problem can be survived if found in time, if luck is on
everyone's side, and if the care at hospital and home are very good.
Loads and loads of fluids are needed to get past the acute kidney
damage, BTW. We have found that ferrets who have needed that help for
a long period tend to develop a life-long habit of drinking more water
than the rest which is good because it keeps their kidneys healthier
long-term so helps provide them with longer lives despite their history.

The type of urolith (stone) usually read about is the struvite stone
and that is because too many places use low quality foods. With poor
quality food that have a high proportion of plant proteins the urine
becomes too alkaline (too basic) and then the components of struvite
precipitate out of the urine. Although having some plant matter in
the food will not cause the urine to get too alkaline, having too much
will so it is entirely a matter of degree -- of moderation. This is
why any ferret who is a rescue from a home or farm which used cheap
food has a decent chance of having such stones present. If you know
that the previous location was a very bad one it pays to use a urine
pH strip (You CAN use the very affordable ones for humans that show a
range to test the urine pH (which should be about 6 in ferrets and
should not be above 6.4 but also should not get too low for the reason
mention in the second paragraph. Note that 6 would be too low for a
human.) If there is a chance that sludge or a stone is present then x-
ray the bladder to be safest because the best scenario is catching a
stone or sludge before some dislodges and catches in urethra or before
it can irritate the bladder badly, or... Because there simply are
places like "backyard breeders" (not the same as "home breeders" or
"private breeders"), because some of the farms are bad, because some
owners just don't care enough, and because some other owners care but
just don't know enough this winds up being the type of urolith/stone
which is most often heard about. These are easily avoided. The
ferrets who get struvite stones tend to have urine pHs of 6.4 or above.

There was an excellent article on this in
but that website is currently giving so many redirects that it can not
get through to the article which is a shame. I hope that this article
becomes available soon (and it may simply be glitch or maintenance
that will be done when you read this), and for public info on another
kidney problem I hope that a way to find the past Ferrets Magazine
veterinary article on raisins causing acute kidney failure also
becomes apparent.

Calcium oxalate stones are also encountered in ferrets. As with
humans the possible best solution so far appears to be to restrict
oxalate sources in the diet. We all need calcium, ferrets included.

I do NOT know if there has been any work to find out if over-dosing of
Vitamin D in ferrets has a chance of playing a part in formation in
uroliths, nor do I know enough to know if it might even be a
reasonable scenario. At some point I have to find time to learn more
on that topic. We humans are very hard to over-dose for D and we
usually don't get enough of it. Ferrets, on the other hand, are like
dogs in that they develop hypercalcemia pretty easily from levels of
D which are lower (See recent FML digests or the FHL Archives for
links on the VIN investigation of one of the Blue Buffalo foods for
this problem.) and that can cause calcium deposits in organs. The
kidney is one of the most commonly affected organs and the heart is
also often affected. I don't know if any of these form in locations
where they can dislodge and pass through the urinary tract as a stone/

There are other less common stones found in mammals but i do not know
how many of those have been found in ferrets; I've simply encountered
mentions of them elsewhere.

I think that I am forgetting another of the ones seen in ferrets but
sadly I failed to create my own pdf of Dr. Murray's excellent article
which was a mistake on my part for which I apologize because if I'd
done so I would be able to help others better as well as having the
reference for myself.

Sukie (not a vet)

Recommended ferret health links:
all ferret topics:

"All hail the procrastinators for they shall rule the world tomorrow."
(2010, Steve Crandall)
On change for its own sake: "You can go really fast if you just jump
off the cliff."
(2010, Steve Crandall)


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