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Thyroid and adrenal function tests in adult male ferrets

1990; American Veterinary Medical Association; Volume: 51; Issue: 1 Linguagem: Inglês

10.2460/ajvr.1990.51.01.32

1943-5681

Darryl J. Heard, Bobby Collins, David L. Chen, John Coniglario,

Growth Hormone and Insulin-like Growth Factors

SUMMARY Effects of thyroid-stimulating hormone ( tsh ) and thyrotropin-releasing hormone ( trh ) on plasma concentrations of thyroid hormones, and effects of acth and dexamethasone on plasma concentrations of cortisol, were studied in adult male ferrets. Thirteen ferrets were randomly assigned to test or control groups of eight and five animals, respectively. Combined (test + control groups) mean basal plasma thyroxine (T 4 ) values were different between the trh (1.81 ± 0.41 μg/dl, mean + SD) and tsh (2.69 ± 0.87 μg/dl) experiments, which were performed 2 months apart. Plasma T 4 values significantly ( P < 0.05) increased as early as 2 hours (3.37 ± 1.10 μg/dl) and remained high until 6 hours (3,45 ± 0.86 μg/dl) after iv injection of 1 IU of tsh /ferret. In contrast, iv injection of 500 μg of trh /ferret did not induce a significant increase until 6 hours (2.75 ± 0.79) after injection, and induced side effects of hyperventilation, salivation, vomiting, and sedation. There was no significant increase in triiodothyronine (T 3 ) values following tsh or trh administration. Combined mean basal plasma cortisol values were not significantly different between acth stimulation (1.29 ± 0.84 μg/dl) and dexamethasone suppression test (0.74 ± 0.56 μg/dl) experiments. Intravenous injection of 0.5 IU of acth /ferret induced a significant increase in plasma cortisol concentrations by 30 minutes (5.26 ± 1.21 μg/ dl), which persisted until 60 minutes (5.17 ± 1.99 μg/dl) after injection. Plasma cortisol values significantly decreased as early as 1 hour (0.41 ± 0.13 μg/dl), and had further decreased by 5 hours (0.26 ± 0.15 μg/dl) following iv injection of 0.2 mg of dexamethasone/ferret. These results indicate that iv injection of 1 IU of tsh /ferret is preferable to iv injection of 500 μg of trh /ferret for thyroid function testing in adult male ferrets. Results of this study also indicated that when trh or tsh is used for the thyroid-stimulation test in male ferrets, plasma T 4 concentrations, instead of T 3 , should be used as the indicator of thyroid response. Additionally, iv injection of 0.5 IU of acth and 0.2 mg of dexamethasone may be used in ferrets for the acth stimulation and dexamethasone-suppression tests, respectively.