01363-A: Comparison of Vitamin B6 levels in a Breed (the Bichon Frise dog) Predisposed to Calcium Oxalate Stones versus Healthy Dogs
Grant Status: Closed
Project SummaryCalcium oxalate urolithiasis represent the second most common canine urolith in North America. As in humans, these stones have a high rate of recurrence with a suspect genetic predisposition. The risk factors for disease are poorly understood and current medical management does not preclude stones from recurring. Vitamin B6 deficiency is a risk factor in humans with calcium oxalate uroliths but this vitamin deficiency not been evaluated in dogs. The goal of this study was to develop an assay to detect Pyridoxyl-5-Phosphate (PLP) (active form of vitamin B6) in canine serum and to assess the impact of vitamin B6 concentrations in dogs with and without Calcium oxalate stones. A High Performance Liquid Chromatography (HPLC) assay was developed to measure vit B6 using pooled canine serum from the ISU VMC clinical pathology laboratory. Serum from dogs with calcium oxalate uroliths and healthy dogs was obtained, light protected, and stored at -80F within 12 hours of collection. Serum concentration of PLP was obtained using a standard curve with known concentrations of research grade PLP in water for each run. Recovery was also measured for each run using a known concentration of PLP in serum. Runs with recoveries lower that 80% were not included in data analysis. For initial assessment for differences in serum concentration between normal versus diseased dogs, dogs were separated into CaOx group (3 dogs) and non-CaOx group (4 dogs). Vitamin B6 concentrations in canine serum were unstable at 2C, and -15C, and when stored at these temperatures there was rapid loss of 20% Vit B6 concentrations in two days and 50% at 14 days, respectively. When stored at -80C for 14 days, approximately 100% of the measurable analyte remained. Freezing and thawing of sera samples resulted in minimal recovery loss after three cycles. This pilot study revealed that the dogs with calcium oxalate urolithiasis were significantly depleted (p value <0.05) in vitamin B6 concentration than those without stones, with mean concentrations of 29 ppb (SD=18) and 123 ppb (SD=70), respectively for each group. Preliminary results comparing serum concentrations of dogs of a predisposed breed (mean levels 55 ppb) to dogs not of a predisposed breed support the contention that a lower vitamin B6 concentration may be a risk factor for Ca Oxalate uroliths in susceptible breeds. An HPLC assay was successfully designed and utilized to reliably measure serum vitamin B6 levels in dogs. Results indicate that dogs with calcium oxalate urinary stones have a vit B6 deficiency relative to dogs without urinary stones. Moreover, some dog breeds reported to be at risk for urinary stones were shown to have reduced serum vit B6 as compared to dogs without urinary stones, suggesting that this may affect disease status. Reduced serum vitamin B6 concentrations may prove to be a risk factor for development of Calcium oxalate urinary stones, and further clinical evaluation in a larger population of dogs having spontaneous uroliths is warranted.
None at this time.
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