Vitamin D metabolism in dogs with and without hypercalciuric calcium oxalate urolithiasis

Abstract

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)2D], and 24,25‐dihydroxyvitamin D [24,25(OH)2D] were measured. The ratios of 25(OH)D/24,25(OH)2D and 1,25(OH)2D/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)2D, 1,25(OH)2D, or 1,25(OH)2D/25(OH)D. Cases had higher 25(OH)D/24,25(OH)2D (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)2D 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)2D 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)2D occurs in a subset of dogs with CaOx urolithiasis. Abnormalities in vitamin D metabolism might contribute to stone risk in dogs.

Urinary calcium assessment and its relation with age, sex and Encephalitozoon cuniculi serological status in otherwise healthy pet rabbits

“…In rabbits there are no studies on the correlation between calcium measurements taken in urine samples collected over 24 hours and those taken in spot urine samples. Although the repeatability and reliability of the method used in the present study for the measurement of spot UC in healthy pet rabbits were good and the reference values of UC and UCC obtained for pet rabbits are expected to be clinically relevant, as is the case in other species,35–37 it would be advisable to obtain these reference values in rabbits by evaluating samples collected over 24 hours and spot urine samples.…”

“…In the clinical setting this technique is not routinely used because of the expense, owner inconvenience and technical difficulty of 24-hour urine collection in animals. Spot urine calcium measurement does not present these inconveniences and has been employed with good results in human beings and animals 35–37. In rabbits there are no studies on the correlation between calcium measurements taken in urine samples collected over 24 hours and those taken in spot urine samples.…”

Vitamin D Metabolism and Profiling in Veterinary Species

“…The assessment of vitamin D metabolite ratios (VMRs) in animals was described as early as 1982 by Horst et al in a study comparing vitamin D metabolites in domestic species [221]. [82]. Although ranges overlapped, 6 out of 19 cases had ratios higher than the highest ratio observed in the control group, with the author postulating that decreased 24-hydroxylase activity on 25(OH)D might contribute to calcium oxalate urolithiasis in some but not all dogs.…”

“…However, the assessment of VMR remains less commonplace in animals than in humans. Recently, Groth et al (2019) examined both the 25(OH)D:24,25(OH) 2 D and 1,25(OH) 2 D:25(OH)D ratios, as well as individual metabolite concentrations in dogs with and without hypercalciuric calcium oxalate urolithiasis [ 82 ]. Interestingly, none of the individual metabolite measurements (25(OH)D, 1,25(OH) 2 D and 24,25(OH) 2 D) yielded significant differences between cases and the control group, neither did the 1,25(OH) 2 D:25(OH)D ratio; however, the 25(OH)D;24,25(OH) 2 D ratio was significantly higher in cases versus controls [ 82 ].…”

“…Recently, Groth et al (2019) examined both the 25(OH)D:24,25(OH) 2 D and 1,25(OH) 2 D:25(OH)D ratios, as well as individual metabolite concentrations in dogs with and without hypercalciuric calcium oxalate urolithiasis [ 82 ]. Interestingly, none of the individual metabolite measurements (25(OH)D, 1,25(OH) 2 D and 24,25(OH) 2 D) yielded significant differences between cases and the control group, neither did the 1,25(OH) 2 D:25(OH)D ratio; however, the 25(OH)D;24,25(OH) 2 D ratio was significantly higher in cases versus controls [ 82 ]. Although ranges overlapped, 6 out of 19 cases had ratios higher than the highest ratio observed in the control group, with the author postulating that decreased 24-hydroxylase activity on 25(OH)D might contribute to calcium oxalate urolithiasis in some but not all dogs.…”