Ultrasonographic appearance of adrenal glands in healthy and sick cats

Abstract

The first part of the study aimed to describe prospectively the ultrasonographic features of the adrenal glands in 94 healthy cats and 51 chronically sick cats. It confirmed the feasibility of ultrasonography of adrenal glands in healthy and chronically sick cats, which were not statistically different. The typical hypoechoic appearance of the gland surrounded by hyperechoic fat made it recognisable. A sagittal plane of the gland, not in line with the aorta, may be necessary to obtain the largest adrenal measurements. The reference intervals of adrenal measurements were inferred from the values obtained in the healthy and chronically sick cats (mean ± 0.96 SD): adrenal length was 8.9-12.5 mm; cranial height was 3.0-4.8 mm; caudal height was 3.0-4.5 mm. The second part of the study consisted of a retrospective analysis of the ultrasonographic examination of the adrenal glands in cats with adrenal diseases (six had hyperaldosteronism and four had pituitary-dependent hyperadrenocorticism) and a descriptive comparison with the reference features obtained in the control groups from the prospective study. Cats with hyperaldosteronism presented with unilateral severely enlarged adrenal glands. However, a normal contralateral gland did not preclude a contralateral infiltration in benign or malignant adrenal neoplasms. The ultrasonographic appearance of the adrenal glands could not differentiate benign and malignant lesions. The ultrasonographic appearance of pituitary-dependent hyperadrenocorticism was mainly a symmetrical adrenal enlargement; however, a substantial number of cases were within the reference intervals of adrenal size.

Figure 1

Ultrasonographic images of feline adrenal glands: (a) a bipolar left adrenal gland in a chronically sick cat (distances 1 = 3.0 mm, 2 = 2.7 mm, 3 = 7.7 mm); (b) an oval left adrenal gland in a healthy cat (distances 1 = 9.8 mm, 2 = 4.7 mm, 3 = 4.6 mm); (c) a fusiform right adrenal gland in a chronically sick cat (distances 1 = 8.1 mm, 2 = 1.5 mm, 3 = 2.4 mm); (d) hyperechoic foci in a hypoechoic left adrenal gland in a chronically sick cat (distances 1 = 11.0 mm, 2 = 4.5 mm, 3 = 4.2 mm); (e) concentric layers detected in a left adrenal gland in a healthy cat

Figure 2

Ultrasonographic images of the right (a) and left (b) adrenal glands in a cat with hyperaldosteronism caused by bilateral carcinoma. The left adrenal gland is roundened, hypoechoic, mildly heterogeneous with well-defined borders. The left adrenal gland length is 24.3 mm and its height 15.1 mm. The right adrenal gland has a normal bipolar shape, a well-defined contour and a hypoechoic parenchyma. The right adrenal gland length is 12.4 mm and its maximal height 6.1 mm

Figure 3

Ultrasonographic images of the left (a) and the right (b) adrenal glands in a cat with pituitary-dependent hyperadrenocorticism. Both adrenal glands are well-delineated, hypoechoic with hyperechoic foci and bipolar. They are mildly over the reference intervals in size: right adrenal gland length = 13.0 mm, height = 6.4 mm; left adrenal gland length = 12.2 mm and height = 7.4 mm