Both struvite and calcium phosphate carbonate form as a consequence of urinary tract infection with bacteria that produce the enzyme urease. Preventing urinary tract infection is the primary method to minimize struvite urolith recurrence. Review our complete Canine Struvite Urolith Recommendations. This urolith commonly forms in breeds that are also at risk for calcium oxalate (Shih Tzu, Bichon, miniature Schnauzer, etc.). We hypothesize that increased calcium excretion in combination with urinary tract infection are important risk factors for this compound stone. Therefore, therapy to minimize struvite should not increase the risk for calcium oxalate.