Measurement of preprandial and postprandial urine calcium to creatinine ratios in male Miniature Schnauzers with and without urolithiasis
Medição de cálcio na urina pré-prandial e pós-prandial para razões de creatinina em Schnauzers Miniatura masculinos com e sem urolitíase
Susan V. Carr, David C. Grant, Stefanie M. DeMonaco and Megan Shepherd
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
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.
calciuresis, cystolithiasis, nephrolithiasis, veterinary