Vitamin D metabolism in dogs with and without hypercalciuric calcium oxalate urolithiasis.
BACKGROUND
There are abnormalities in vitamin D metabolism in people with calcium nephrolithiasis, but limited data are available on vitamin D status in dogs with calcium oxalate (CaOx) urolithiasis.


OBJECTIVE
To compare serum concentrations of vitamin D metabolites in dogs with and without hypercalciuric CaOx urolithiasis.


ANIMALS
Thirty-eight dogs with (n = 19) and without (n = 19) a history of CaOx urolithiasis and hypercalciuria.


METHODS
Retrospective cross-sectional study. Serum 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)2 D], and 24,25-dihydroxyvitamin D [24,25(OH)2 D] were measured. The ratios of 25(OH)D/24,25(OH)2 D and 1,25(OH)2 D/25(OH)D were compared between cases and controls.


RESULTS
There were no significant differences between cases and controls when comparing 25(OH)D, 24,25(OH)2 D, 1,25(OH)2 D, or 1,25(OH)2 D/25(OH)D. Cases had higher 25(OH)D/24,25(OH)2 D (median = 1.40, range = 0.98-1.58) compared to controls (median = 1.16, range = 0.92-2.75; P = .01). There was overlap in the ranges for 25(OH)D/24,25(OH)2 D between cases and controls, but 6 cases (32%) had ratios above the control dog range. There was a moderate positive correlation between the ratio of 25(OH)D/24,25(OH)2 D and urinary calcium-to-creatinine ratios (r = 0.40, 95% confidence interval = 0.10-0.64; P = .01).


CONCLUSIONS AND CLINICAL IMPORTANCE
These data suggest that decreased conversion of 25(OH)D to 24,25(OH)2 D occurs in a subset of dogs with CaOx urolithiasis. Abnormalities in vitamin D metabolism might contribute to stone risk in dogs.
['Groth|Elizabeth M|EM|https://orcid.org/0000-0002-3578-3813', 'Lulich|Jody P|JP|https://orcid.org/0000-0002-2338-1569', 'Chew|Dennis J|DJ|', 'Parker|Valerie J|VJ|https://orcid.org/0000-0001-6505-8068', 'Furrow|Eva|E|']
D000818:Animals D002118:Calcium D002129:Calcium Oxalate D016022:Case-Control Studies D003430:Cross-Sectional Studies D004283:Dog Diseases D004285:Dogs D005260:Female D008297:Male D012189:Retrospective Studies D052878:Urolithiasis D014807:Vitamin D
hypercalciuria stones calcitriol canine