Exploration of Vitamin D Metabolism in Indoor-Housed Hoffmann’s Two-Toed Sloths (Choloepus hoffmanni)
Abstract
Two-toed sloths are unique arboreal members of the superorder Xenarthra, in which disease related to calcium metabolism has been reported.1-3 This research surveyed multiple biomarkers of calcium and vitamin D metabolism, measured epidermal 7-dehydrocholesterol (7-DHC) concentrations in two locations, and evaluated the use of dried blood spots for the measurement of 25-hydroxyvitamin D (25[OH]D), in Hoffmann’s two-toed sloths (Choloepus hoffmanni). Samples were collected from nine indoor-housed healthy sloths during routine examinations. Serum was analyzed for 25(OH)D2/D3, 1,25(OH)2D2/D3, and 24,25(OH)2D2/D3 parathyroid hormone (PTH); ionized calcium (iCa); and minerals (calcium [Ca], magnesium [Mg], and phosphorus [P]). Full-thickness lumbar and abdominal skin biopsies were analyzed for 7-DHC. Whole blood was collected on a dried blood spot (DBS) card and analyzed for 25(OH)D2/D3.
All detectable vitamin D metabolites were analogues of D3, with mean±SD of 25.1±7.2 ng/ml for 25(OH)D3, 54.2±18.9 pg/ml for 1,25(OH)2D3, and 7.7±3.2 ng/ml for 24,25(OH)2D3. Mineral values were within expected ranges. Average PTH was 0.2±0.17 pmol/L, and iCa was 1.1±0.14 mmol/L. There was a significantly higher concentration of epidermal 7-DHC in the abdominal (184.4 ng/g) compared to lumbar (94.87 ng/g) biopsy samples (p=0.038). Statistical analysis using Passing-Bablok regression analysis, Bland-Altman plots, and paired t-test found good agreement between DBS and serum samples for measurement of 25(OH)D3, without constant or proportional bias. This research generates baseline data regarding vitamin D and calcium metabolism in Choloepus hoffmanni and provides a foundation for future research projects in this species, designed to improve husbandry and nutrition recommendations and reduce the incidence of disease conditions related to calcium homeostasis.
Acknowledgments
The authors thank Mazuri® Exotic Animal Nutrition, who provided the funding for this research, as well as the animal care staff of the Rosamond Gifford Zoo for assistance with sample collection and processing.
Literature Cited
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