ROYAL CANIN DOG URINARY s/o 2KG Struvite dissolution Urinary S/O Canine effectively dissolves struvite uroliths. In addition, an acidic urinary pH is unfavourable to the development of bacteria, which are frequently associated with struvite uroliths. Low RSS Low RSS (relative super saturation) diets encourage an undersaturated urinary environment, unfavourable to the development of struvite and calcium oxalate crystals. Urine dilution Diluting urine decreases the urinary concentration of struvite and calcium oxalate crystals. Greater urinary volumes also ensures regular bladder wash-out. Low magnesium Magnesium is a component of struvite (magnesium ammonium phosphate) uroliths.