• Diet
• Hill's u/d diet is 85-90% effective alone in preventing urate urolithiasis. If urate crystals persist on urinalysis, allopurinol is added at ~7-10 mg/kg q 12 hrs.
  
• IVD Select Care Vegetarian Formula is claimed to be appropriate for Dalmatians' and dogs' metabolic urinary stones as it has low purine levels and added K+ citrate.
  
• Renal failure diet plus low-dose allopurinol. Efficacy is uncertain.
  
• Lite Salt (K Cl)
• Salt supplementation may not be required as low protein diets promote diuresis. While potassium chloride is stated to have an advantage over NaCl, urine is less concentrated with use of either salt and so urate concentration also decreases.
  
• Treatment may not need to be lifelong, as risk appears to decrease after 6 years of age.
  

• Measure 24-hour urinary urate excretion after 1-2 months on preventive therapy. During the collection period, provide water, feed the usual diet, and administer allopurinol at the usual dose. Collect all urine produced during the 24-hr. period, store in a clean, covered container and keep cold. Measure and record the total volume of urine produced (in deciliters; 1 deciliter=100 mL). Mix the urine thoroughly to resuspend any precipitate, place an aliquot of at least 2 mL into a RTT (not SST), and submit for determination of uric acid concentration. Multiply the laboratory result (reported in mg/dL) by the number of deciliters of urine produced in 24 hrs.
  The aim is to achieve ~300 mg/urate/day, as >350 mg/day increases risk for urate stones and <250 mg/day increases risk for xanthine stones. No data is available about whether 12-hour urine collection would provide accurate results.
  
• Urine "spot" testing (urine urate:creatinine ratio) has been found to be too variable and does not correlate well with 24-hour urine urate excretion.
  
• Check periodic urinalyses for urate crystalluria. Fasting urine pH should be 7.1-7.7. Check for presence and magnitude of crystalluria. Ammonium hydroxide urate crystals are seen in acidic, neutral or alkaline urine and have a thorn apple or amorphous appearance. Amorphous urates are seen in acid urine and may be difficult to distinguish from amorphous phosphates, which are seen in alkaline urine. Uric acid crystals are seen in acid urine, are much less common, and have rhomboid shape.

References: Bartges et al, JAVMA 204: 1914-1918, 1994; Dodds, Adv Vet Sci Comp Med 39: 29-96, 1995; Ling and Sorenson, Current Vet Therapy XII, pp. 985-988,1995;
Antech consultants conference with Dr. Joseph Bartges.