Calcium oxalate uroliths are highly recurrent. In a retrospective study at the University of Minnesota, 42% of the canine patients with calcium oxalate uroliths had recurrences within 2 years. Medical protocols that will promote dissolution of calcium oxalate uroliths are not yet available. Therefore, we recommend preventative therapy to help control risk factors associated with calcium oxalate urolithiasis.
If uroliths recur despite efforts to minimize risk factors, early detection will facilitate their removal by voiding urohydropropulsion. Uroliths removed by voiding urohydropropulsion should be quantitatively analyzed. If attempts to remove lower urinary tract uroliths are unsuccessful, surgery remains the most reliable way to remove those that are symptomatic, or have a high potential of causing obstruction or secondary urinary tract infection. We emphasize, however, that surgery may be unnecessary for clinically inactive calcium oxalate uroliths.
All prevention recommendations should be adjusted to meet individual patient's needs. We recommend periodic follow-up urinalyses, serum chemistry profiles, including TCO2 and radiographs or ultrasound.
to minimizecalcium oxalate urolith formation Avoid these risk factors
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RISK FACTOR
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RATIONALE
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Calcium supplements independent of meals
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Promotes excessive urine calcium excretion
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Concentrated urine
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Decreased urine volume results in increased urine concentration of calculogenic precursors.
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Drugs (e.g. ammonium chloride, methionine) and diets (those designed to dissolve or prevent struvite uroliths) promoting acidosis and acidic urine.
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Promotes hypercalciuria and decreases urinary citrate excretion.
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Dry Diets
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Are associated with formation of more concentrated urine and thus higher concentrations of calculogenic minerals.
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Foods with high oxalate content
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Promotes increased urinary oxalate excretion.
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Furosemide
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Promotes increased urinary calcium excretion.
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Glucocorticoids
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Promotes skeletal calcium release and increased urinary calcium excretion.
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Human Food
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In an epidemiologic study, feeding human food was associated with increased risk of calcium oxalate uroliths in dogs.
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Restricting voluntary urination
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Prolonged crystal retention promotes crystal growth.
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Vitamin C supplements
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Serve as a substrate for conversion to oxalic acid.
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Vitamin D supplements
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Promotes intestinal calcium absorption and subsequent hypercalciuria.
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Water restriction
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Decreased urine volume results in increased urine concentration of calculogenic precursors.
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Further references:
Lulich JP, Osborne CA, et al: Nonsurgical removal of urocystoliths by voiding urohydropropulsion. In Journal of the American Veterinary Medical Association. Vol 203, pp. 660-663, 1993
Osborne CA, et al.: Canine and Feline Urolithiasis: Relationship of Etiopathogenesis to Treatment and Prevention. In Canine and Feline Nephrology and Urology, Osborne and Finco 1995, pp 798-888.
Lulich JP, Osborne CA, et al: Management of Canine Calcium Oxalate Urolith Recurrence. In Compendium on Continuing Education for the Practicing Veterinarian. Vol 20 (2), pp 178-189, Feb 1998.
Lulich JP, Osborne CA, Lekcharoensuk C, et al: Canine calcium oxalate urolithiasis: case-based applications of therapeutic principles. VCNA 1999;29:123-139.
Osborne CA, et al.: Canine Urolithiasis. Small Animal Clinical Nutrition 4thed., 2000, pp. 605-688.
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