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#1
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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 |
#2
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"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 |
#3
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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 |
#4
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"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. |
#5
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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 |
#6
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"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 |
#7
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hi,
an x-ray showed nothing and its hard for the vet to analyze an ultrasound, she is not an expert at that.. after the removal of the cathetere (second catheterization in 2 weeks) the urine still contained a few crystals which showed in the microscope as typical struvite ones (rectangular envelope-shaped). is it logical since the cat is being fed canned hills s/d for the last 2 weeks? he is now straining to urinate but he eventually manages to empty his bladder.. the vet said if he has another blocakge he'll go for urehtrostomy.. what else is there to do ? thanks.. |
#8
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"tunic" wrote in message lkaboutpets.com... hi, an x-ray showed nothing and its hard for the vet to analyze an ultrasound, she is not an expert at that.. after the removal of the cathetere (second catheterization in 2 weeks) the urine still contained a few crystals which showed in the microscope as typical struvite ones (rectangular envelope-shaped). is it logical since the cat is being fed canned hills s/d for the last 2 weeks? he is now straining to urinate but he eventually manages to empty his bladder.. the vet said if he has another blocakge he'll go for urehtrostomy.. what else is there to do ? thanks.. Are you free feeding (ad libitum) your cat or do you feed him twice a day (b.i.d.)? Feeding releases bicarbonate which produces an alkaline tide that causes transient alkalinization of the urine. Free-feeding protracts postprandial alkalinization of the urine throughout the day. Although the alkaline tide is much "higher" after b.i.d. feeding, its shorter in duration. Enough time elapses between meals for natural acidity to return and disolve struvite. At urine pH less than 6.1, struvite does not form regardless of the magnesium concentration of the diet. So if you're finding struvite in pH 6 urine, the crystals may not be struvite. Buy a tube of urine dipsticks and monitor his urine pH throughout the day. I hope you find a solution quickly. Good luck. Phil |
#9
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no luck...
i'm feeding him twice a day but he seems to have been blocked again i took him to the vet and she pressed his bladder and only a tiny flow came out. so there must be a stone in his urethra which cant be removed and the only solution is PU.. if there are any final suggestions please let me know thank you very much |
#10
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"tunic" wrote in message lkaboutpets.com... no luck... i'm feeding him twice a day but he seems to have been blocked again i took him to the vet and she pressed his bladder and only a tiny flow came out. so there must be a stone in his urethra which cant be removed and the only solution is PU.. if there are any final suggestions please let me know thank you very much I'm running out of alternatives to surgery. In some cases acidifers are administered and a urinary catheter is sewn in place for several days to keep the urine flowing while the stone dissolves. This is a little risky because acidification of the urine is not without potential toxicity (hemolytic anemia, met hemoglobinemia, and Heinz body formation, and possibly renal damage). Acidification may be of no benefit if your cat is obstructed with a plug instead of a stone. Also, a difinitive analysis of struvite has not been made. There are usually only 2 places where a stone/plug can lodge. One place is where urethra narrows, sort of like a funnel, where its passes over the pelvis into the penis. (see illustration on my site). http://www.maxshouse.com/Anatomy/ana...enital_sys.jpg The other place is in the tip of the penis where urethra is the narrowest. *If* the obstruction is in the tip of the penis, and your vet has keen surgical skills, you just might, *might* get through this crisis with a urethrotomy instead of a urethrostomy. A urethrotomy differs from a urethrostomy in that only a temporary opening is made in the penis and urethra to remove a lodged stone or plug and to provide an opening for temporary urine flow. The layers of skin, penis, and urethra are opened, then sutured closed in reverse order. The cat gets to keep his penis. Since the technique is very similar for both procedures, perhaps your vet can begin with a urethrotomy and continue on to a urethrostomy if the stone is not lodged in the tip of the penis. However, I'm very concerned about the patency of the urethra. Repeated blockages and catheterizations may have severely damaged the urethra leaving no alternatives to a perineal urethrostomy. At this stage, and due to the likelihood of urethral damage and the high risk of obstruction-induced oliguric acute renal failure, and the discomfort and stress of repeated blockages and catheterizations, if he were my cat, I think I would go ahead with the urethrostomy. UTIs are trivial in comparison to the other alternatives. But that's merely my opinion and I could be wrong. It looks like we're back to where we started. I wish I could be more helpful. Please keep me posted. Best of luck. Phil |
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