Measurement of preprandial and postprandial urine calcium to creatinine ratios in male Miniature Schnauzers with and without urolithiasis

摘要

Background We aimed to identify a simple test for excessive calciuresis and predict calcium oxalate (CaOx) disease in Miniature Schnauzers. We investigated the impact of postprandial time on the urine calcium to creatinine ratio (UCa/Cr) in male dogs of this breed, with the goal of improving the utility of the UCa/Cr. Hypotheses (1) Significant differences will exist in preprandial and postprandial UCa/Cr between CaOx urolith‐forming and control Schnauzers. (2) The UCa/Cr will increase significantly from the first morning baseline at ≥ 1 postprandial time point(s) in both control and CaOx urolith‐forming dogs. (3) Biochemical abnormalities and other variables may be associated with urolith status. Animals Twenty‐four male Miniature Schnauzer dogs, consisting of 9 with (urolith formers) and 15 without (controls) CaOx uroliths. Methods Urine was collected before and 1, 2, 4, and 8?hours after feeding a standardized diet. Receiver operator characteristic curve analysis was performed to identify the UCa/Cr cutoff that most accurately differentiates dogs based on urolith status. Results Urolith formers had significantly higher mean UCa/Cr over the course of 8?hours. The postprandial change in UCa/Cr was not significant at any time point between or within groups. The cutoff UCa/Cr value of 0.06 had a specificity of 93% (95% confidence interval [CI], 80%‐100%) and a sensitivity of 56% (95% CI, 21%‐86%) for identifying CaOx urolithiasis. Conclusions and Clinical Importance Urolith‐forming male Miniature Schnauzers have excessive calciuresis, and the postprandial sampling time up to 8?hours is not critical. This simple urine measurement has potential as a marker of CaOx disease.