X-ray-computed tomography (CT), nephrotomography, and ultrasonography were performed in 10 clinically healthy dogs (weighing 14 to 33 kg) to visualize the adrenal glands. In all 10 dogs, CT enabled visualization of both adrenal glands. Cross-sectional diameter was measured accurately. The size and shape of CT sections of the adrenal glands varied widely because of individual differences in the actual size and shape of the adrenal glands and because of their position in the plane of the CT scans. In 5 dogs, nephrotomography enabled visualization of 1 or both adrenal glands as oblong craniocaudal-directed densities in the craniodorsal portion of the abdomen. In 7 dogs, transverse ultrasonography enabled visualization of 1 or both adrenal glands as round or oval hypoechoic structures in the surrounding hyperechoic fat.

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 (T4) values were different between the TRH (1.81 +/- 0.41 microgram/dl, mean +/- SD) and TSH (2.69 +/- 0.87 microgram/dl) experiments, which were performed 2 months apart. Plasma T4 values significantly (P < 0.05) increased as early as 2 hours (3.37 +/- 1.10 microgram/dl) and remained high until 6 hours (3.45 +/- 0.86 microgram/dl) after IV injection of 1 IU of TSH/ferret. In contrast, IV injection of 500 microgram 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 (T3) values following TSH or TRH administration. Combined mean basal plasma cortisol values were not significantly different between ACTH stimulation (1.29 +/- 0.84 microgram/dl) and dexamethasone suppression test (0.74 +/- 0.56 microgram/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 microgram/dl), which persisted until 60 minutes (5.17 +/- 1.99 microgram/dl) after injection. Plasma cortisol values significantly decreased as early as 1 hour (0.41 +/- 0.13 microgram/dl), and had further decreased by 5 hours (0.26 +/- 0.15 microgram/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 microgram 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 T4 concentrations, instead of T3, 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.