| Summary: | Little research have been published concerning endocrine profiles in bears, the existing literature mainly focusing on sun (Ursus malayanus) and Formosan bear (Ursus thibetanus formosanus). Almost no information is available on the endocrine profile of polar bears (Ursus maritimus). Our present research aims at evaluating thyroid hormones profile in captive pubertal polar bears through the non-invasive measurement of thyroid hormones in feces. Samples were collected from two juvenile polar bear, one male and one female, and stored frozen until analysis. Hormone extraction was performed on 0.3 g homogenized feces with a double ethanol extraction and analyzed with commercial ELISA kits for thyroxine (T4) and triiodothyronine (T3). In all samples T4 presented higher concentrations than T3. The female bear showed higher level of fecal T3 than the male (40.67 ± 55.49 ng/g vs 25.87 ± 4.78 ng/g respectively). Similarly, a higher variation in T3 and T4 excretion was observed in the female bear with respect to male. Finally, a decrease in T4 excretion was observed in both bears in summer months. Our preliminary results strongly suggest that feces can be used as tool for monitoring thyroid function in bears. This is also the first study presenting data concerning thyroid hormones from non-invasive, fecal samples in bears.
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