Rapid improvement in vitamin D status with dietary 25-hydroxycholecalciferol in vitamin D insufficient dogs

Vitamin D insufficiency is associated with various disease processes. We determined whether consumption of a diet supplemented with HyD , a 25-hydroxycholecalciferol (25(OH)D ) source, would safely increase plasma 25(OH)D concentrations in Golden Retrievers with low vitamin D status. We hypothesised that dietary supplementation with HyD would rapidly increase and sustain plasma 25(OH)D levels in healthy Golden Retrievers with low vitamin D status compared with supplementation with vitamin D . Of fifty-seven privately owned dogs recruited with written owner consent, eighteen dogs with low vitamin D status were identified and sorted between two groups to have similar initial plasma 25(OH)D concentrations, sex distributions, ages and body weights. Dogs of each group were fed a dry dog food supplemented with either 16 μg/kg of 25(OH)D as HyD ( 10) or 81 μg/kg of cholecalciferol (D ) ( 8) for 4 months. Plasma 25(OH)D concentrations were determined monthly. A significant time effect ( < 0⋅001) and time by group interaction ( = 0⋅0045) were found for monthly determined plasma 25(OH)D concentrations. Dogs fed the HyD -supplemented diet experienced a 40⋅5 % rise in plasma 25(OH)D values after 1 month ( < 0⋅001) and no change thereafter. Plasma 25(OH)D values of dogs supplemented with vitamin D did not increase ( > 0⋅05) and were less than values of dogs supplemented with HyD ( = 0⋅044). With few exceptions, average haematologic, biochemical and urinalyses results remained within the reference range for both groups. Dietary supplementation with HyD is sufficient to safely increase and sustain plasma 25(OH)D levels in healthy dogs.