Cat Urolithiasis

hello,

my cat (male, 3.5 years old) had urethra blockage twice before (in a 1.5
year period) due to struvite crystal formation in his bladder
he has been on a specific diet (hills c/d) which is a low-magnesium
acidifying food in order for the crystals to be dissolved. he was also fed
another acidifying medicine (named methygel)

yesterday he had another blockage, i took him to the vet and he has been
catheterized. the vet took urine samples and measured the pH which was
very acidic (6) and checked them at the microscope but couldnt definitely
determine if the crystals were sturvite or calcium ocalate. one logical
explanation is that the acidifying diet aimed at struvite crystals made
way for the formation calcium oxalate ones. but the clues tend to
sturvite..

my questions a
1. is it possible for sturvite to be formed in such an acidic environment
(pH = 6)?
(though today, after being fed a normal food, the pH was 8.5!)

2. how easy is it to determine wether it's struvite or calcium oxalate? in
the microscope there can be seen a variety of shapes and forms of crystals
(but not a great number of them). is there another more accurate method?


any help would be valuable
thank you

"tunic" wrote in message
lkaboutpets.com...
hello,

my cat (male, 3.5 years old) had urethra blockage twice before (in a 1.5
year period) due to struvite crystal formation in his bladder
he has been on a specific diet (hills c/d) which is a low-magnesium
acidifying food in order for the crystals to be dissolved. he was also fed
another acidifying medicine (named methygel)

yesterday he had another blockage, i took him to the vet and he has been
catheterized. the vet took urine samples and measured the pH which was
very acidic (6) and checked them at the microscope but couldnt definitely
determine if the crystals were sturvite or calcium ocalate. one logical
explanation is that the acidifying diet aimed at struvite crystals made
way for the formation calcium oxalate ones. but the clues tend to
sturvite..

my questions a
1. is it possible for sturvite to be formed in such an acidic environment
(pH = 6)?
(though today, after being fed a normal food, the pH was 8.5!)

Whenever you find crystals in acid urine it means that either the urine is
not sufficiently acidified or insufficient time has elapsed for the crystals
to dissolve. If urine pH is high for any length of time crystals can form.

Also, a single determination of acidic urine does not mean the urine was
sufficiently acidic to be undersaturated with struvite before the
obstruction --- the fact that you found crystals proves it wasn't.

Another thing to remember is anorexia usually develops after cats devlop a
urethral obstruction - most cats aren't brought to vet for at least 24 hours
after their last meal -- this increases the probability that the urine pH
will be acidic when its tested.



2. how easy is it to determine wether it's struvite or calcium oxalate? in
the microscope there can be seen a variety of shapes and forms of crystals
(but not a great number of them). is there another more accurate method?


Optical crystallography, thermal analysis, infrared spectrophotometry,
electron microprobe analysis, x-ray diffraction, -- or a combination of
these methods. Microscopic examination only identifies the outside of a
urolith. Some uroliths have a mixed composition - IOW, they have a nucleus
composed of calcium oxalate and a shell composed of struvite. That's why
quantitative mineral analysis, rather than qualitive analysis is so
important.

Also, there's a big difference between struvite uroliths and struvite
urethral plugs. Uroliths are made up of mostly of magnesium ammonium
phosphate (MAP) and small amounts of matrix. Struvite plugs are usually
made up of large amounts of matrix mixed with small amounts of MAP.. Some
urethral plugs are made up of organic matrix, sloughed tissue, blood, and/or
debris, and others are form in association with an infection
(infection-induced struvite).

Plugs are more common in male cats than actual uroliths - which are more
common in females. If your cat has struvite plugs, the prescription diet
isn't going to help that much.

hth,

Phil

thanks for your response

Optical crystallography, thermal analysis, infrared spectrophotometry,
electron microprobe analysis, x-ray diffraction, -- or a combination of
these methods

unfortunately, most of these methods arent available where i live (a small
town in greece). the only thing they could do to identify the case was the
cat to have formed a stone and this stone to be surgically removed and
examined..

anyway, the vet has come to the conclusion that it is sturvite uroliths
(there werent any signs of infection, the cat was in perfect health even
during the hospitalization)
and we are currently feeding with Hill's s/d diet in order to dissolve
them -but meanwhile he had a couple of blockages which we got over with
temporary catheterization
i think the last resort will be urethrostomy..

the vet assured me that there wont be any side-effects by urethrostomy
though i have read that the cat will be more prone to bladder infections
and the stone formation is going to get more intense- it just wont induce
blockage, can you shed any light to this?
is urethrostomy to be considered as the last resort or is it a common
procedure?

thanks

"tunic" wrote in message
lkaboutpets.com...
thanks for your response

Optical crystallography, thermal analysis, infrared spectrophotometry,
electron microprobe analysis, x-ray diffraction, -- or a combination of
these methods

unfortunately, most of these methods arent available where i live (a small
town in greece). the only thing they could do to identify the case was the
cat to have formed a stone and this stone to be surgically removed and
examined..

anyway, the vet has come to the conclusion that it is sturvite uroliths
(there werent any signs of infection, the cat was in perfect health even
during the hospitalization)
and we are currently feeding with Hill's s/d diet in order to dissolve
them -but meanwhile he had a couple of blockages which we got over with
temporary catheterization
i think the last resort will be urethrostomy..

the vet assured me that there wont be any side-effects by urethrostomy
though i have read that the cat will be more prone to bladder infections
and the stone formation is going to get more intense- it just wont induce
blockage, can you shed any light to this?
is urethrostomy to be considered as the last resort or is it a common
procedure?


Perineal urethrostomy sure is a last resort; the procedure literally turns a
male cat into an anatomical female. First the scrotal skin and prepuce are
removed to free and expose the penis. Then the muscles that hold the penis
to the pelvic bones are cut - this allows the penis to be pulled outside of
the body a little more than it normally is. The penis is then split along
the urethra to the widest part of the urethra. Then, the opened urethra is
(very delicately) sutured to the skin, part of the penis is removed, and
all skin edges are closed. If its done right, the cat is now sort of an
anatomical female with a w i d e urethral opening so stones or crystals
can't jam and plug the cat. But the cat will not have the host defense
system of a female and will be prone to UTIs.

I watched a few procedures and I can tell you its not as bad as it sounds...
although I did get the chills.

P.U.s are usually only necessary for calcium oxalate cases because CaOx
can't be dissolved. If your vet is recommending a PU in a struvite case,
its quite possible he damaged the urethra during catheterization.

This is *definitely* a last resort procedure so I would seek a second
opinion if I were you.

Good luck.

Phil.

hi,

today my cat had another blockage which was due to a stone which had moved
down in the urethra. the vet had great difficulty passing the cathetere
and could feel the resistence by the stone (it is almost certain that its
struvite stone) but eventually it went through
the urine was quite clear of crystals (and blood) so we presume that it
was a sole stone that has pretty much been dissolved by the
catheterization
but how safe is this assumption? should we proceed to PU even knowing that
it is a struvite case? would an x-ray show anything?
i'm really hopeless..

ps i am in close contact with the vet so i'm aware of all her movements

"tunic" wrote in message
lkaboutpets.com...
hi,

today my cat had another blockage which was due to a stone which had moved
down in the urethra. the vet had great difficulty passing the cathetere
and could feel the resistence by the stone (it is almost certain that its
struvite stone) but eventually it went through
the urine was quite clear of crystals (and blood) so we presume that it
was a sole stone that has pretty much been dissolved by the
catheterization
but how safe is this assumption? should we proceed to PU even knowing that
it is a struvite case? would an x-ray show anything?
i'm really hopeless..

ps i am in close contact with the vet so i'm aware of all her movements


Struvite is radiodense so it should detectable on x-rays - an ultrasound
would be idea. I would certainly opt for x-rays or ideally ultrasounds
before going forward with such a drastic procedure or risking another
obstruction. Remember, if an obstruction occurs over the weekend or your
vet is unavailable, your cat could die - complete obstruction produces a
pathophysiologic state equivalent to oliguric acute renal failure.

If the problem was caused by a single stone, the cost of the imaging is
negligible compared to the surgery and treatment for recurring UTIs - not to
mention sparing the cat of the trauma and stress.

Phil