Cutaneous concentrations of 7-dehydrocholesterol in Hoffmann's two-toed sloths (Choloepus hoffmanni) in managed care.

Hoffmann's two-toed sloths (Choloepus hoffmanni) are unique animals popular in zoological settings. The role of vitamin D in the maintenance of calcium homeostasis in this species is unexplored, although disorders of calcium homeostasis have been reported in managed sloths, including urolithiasis and soft tissue mineralization. This study assessed cutaneous concentrations of 7-dehydrocholesterol (7-DHC) in nine indoor-housed Hoffmann's two-toed sloths, as a means of evaluating the potential for cutaneous photobiosynthesis of vitamin D3 . Samples were obtained from both abdominal and lumbar regions of the skin to assess for regional variation in 7-DHC concentration. The average concentration of 7-DHC in the sloth skin was low (0.197 ± 0.02 nmol/cm2 ). Location had a significant effect on 7-DHC level only when concentrations were expressed based on the wet weight of the sample (ng/g), but levels were similar when values were normalized to biopsy surface area (nmol/cm2 ).

VITAMIN D STATUS OF INDOOR-HOUSED HOFFMANN'S TWO-TOED SLOTHS (CHOLOEPUS HOFFMANNI): A PILOT STUDY.

Disorders of calcium homeostasis have been reported with some frequency in two-toed sloths, yet little investigation has been performed on vitamin D and mineral metabolism in these species. This study evaluates biomarkers involved in vitamin D and calcium metabolism in a group of nine managed Hoffmann's two-toed sloths (Choloepus hoffmanni), correlated with diet analysis. Serum was analyzed for both vitamin D2 and D3 metabolites, minerals (calcium [Ca], phosphorus [P], and magnesium [Mg]), parathyroid hormone (PTH), and ionized calcium (iCa). The diet was analyzed for proximate nutrients, minerals and vitamins D2 and D3, and feed intake was estimated. Average values reported for D3 metabolites, including 25(OH)D3, 1,25(OH)2D3, and 24,25(OH)2D3, were 25.1 ng/ml, 52.23 pg/ml, and 7.65 ng/ml, respectively. Average PTH was 0.22 pmol/L while average iCa was 1.46 mmol/L. Values reported for Ca, P, Mg were within expected ranges. Dietary concentration of D3 was 6.7 ng/g and the average daily intake per sloth was 113.7 IU/kg body weight. No detectable levels of vitamin D2 metabolites 25(OH)D2, 1,25(OH)2D2, or 24,25(OH)2D2 were found in the diet or serum. These data will serve as a starting point for future investigations into the vitamin D metabolism and calcium homeostasis of two-toed sloths to improve the health in managed settings.

EVALUATION OF 25-HYDROXYVITAMIN D IN HOFFMANN'S TWO-TOED SLOTHS (CHOLOEPUS HOFFMANNI) USING DRIED BLOOD SPOTS ANALYZED BY LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY.

Although biochemical analytes have typically been measured using serum or whole blood samples, an increasing number of assays are validated for measurement of analytes from dried blood spots (DBS) on filter paper. DBS techniques are minimally invasive, require only a small sample volume, and simplify processing, storage, and shipment of samples. These qualities make DBS-based assays ideal for sampling of wildlife species in both captive and field settings. In this study, a liquid chromatography-tandem mass spectrometry assay was evaluated for measurement of 25-hydroxyvitamin D in sloths. Paired serum and DBS samples were collected from nine healthy captive Hoffmann's two-toed sloths (Choloepus hoffmanni). Statistical analysis using Passing-Bablok regression analysis, Bland-Altman plots, and the Wilcoxon signed-rank tests found good agreement between 25-hydroxyvitamin D3 measurements in serum and DBS samples. Constant and proportional bias were absent. Results from this study support the use of DBS samples for the evaluation of vitamin D status in Hoffmann's two-toed sloths and provide a foundation for further studies to validate this technique.