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Duking out the treatment of struvite/urate urolithiasis

"Duke" is a 12-yr-old MN Shih Tzu presented for intermitted bloody urine. Antibiotics initially resolved clinical signs, but hematuria recurred. Radiographs identified a moderately radiopaque bladder stone (Figure 1). "Duke" was anesthetized, the stone was fragmented by laser lithotripsy (video 1), and the fragments were removed by basket retrieval and voiding urohydropropulsion. Quantitative analysis of the stone was 70% struvite and 30% urate (Figure 2). Taking a second look at the radiograph, liver size was normal but small. Serum concentrations of liver enzymes were unremarkable: ALP = 28 U/L (normal = 22-92), AST U/L = 22 (normal = 16-44) and ALP U/L = 25 (normal = 8 to 139).

How would you manage this dog?

Figure 1 - radiograph showing a moderately radiopaque bladder stone
Figure 1


  1. Shih Tzu's are predisposed to porto-vascular shunts. Consider evaluating bile acids in breeds at risk for liver shunts. Postprandial serum bile acid concentration was high (52 µmol/L; normal is 15 to 25).
  2. Culture urine, struvite uroliths in dogs are usually due to a urinary tract infection.
multiple canine struvite urate bladder stones
Figure 2


  1. To prevent urate, consider canned lower purine/protein foods usually formulated with egg, dairy, or vegetable proteins that result in a more neutral or alkaline urine pH (e.g. Hill's l/d, u/d, i/d Sensitive Canine, HA Hydrolyzed, others).
  2. To prevent struvite, control urinary tract infection with periodic urine cultures and appropriate antimicrobics, when needed.

If bile acids were normal, we would still avoid urine acidification (a common feature of struvitolytic diets) because urate is more soluble in alkaline urine and therefore less likely to precipitate out.

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