Ultrasonographic examination of the adrenal gland and evaluation of the hypophyseal-adrenal axis in 20 cats.

The adrenal glands of 20 healthy, non-sedated cats were examined ultrasonographically; visualisation and assessment was possible in all cases. In comparison with the surrounding tissue, the adrenal glands were hypoechoic and two distinct zones could be differentiated in six of the cats. The length and width of the adrenal glands varied from 0.45 to 1.37 cm and 0.29 to 0.53 cm, respectively, and both dimensions could be reliably reproduced. The adrenal glands did not differ between male and female cats, and, in comparison to dogs, those of cats are more easily visualised ultrasonographically. The basal cortisol value ranged from 2.0 to 79 micrograms/litre. Values 30 and 60 minutes after administration of ACTH (0.125 mg/cat intramuscularly) varied from 36 to 126 micrograms/litre. The basal value of aldosterone ranged from 4 to 618 pg/ml. Values 30 and 60 minutes after administration of ACTH varied from 100 to 832 pg/ml. In all cats, suppression of the cortisol value below the level of detection (< 2.0 micrograms/litre) occurred four and eight hours after the administration of dexamethasone (0.1 mg/kg intravenously).