Ultrasonographic evaluation of the adrenal glands in dogs

To determine normal adrenal gland size by means of ultrasonography in dogs and to determine the value of ultrasonography in the diagnosis of pituitary-dependent hyperadrenocorticism (PDH) in dogs.

Prospective observational study.

62 dogs: 20 healthy dogs, 20 dogs with non-endocrine disease, and 22 dogs with untreated PDH.

Length and maximum and minimum diameter of the adrenal glands were measured ultrasonographically. Multiple regression and correlation analyses were used to determine whether body weight, kidney length, aortic diameter, or age was related to adrenal gland size. Two-tailed t-tests and multiple linear regression analysis were used to compare values between groups. Sensitivity and specificity of using ultrasonographic measurement of adrenal gland size as a diagnostic test for PDH were determined.

There was a significant linear relationship between adrenal gland length, but not maximum and minimum diameters, and body weight, aortic diameter, and kidney length in healthy dogs and in dogs with nonendocrine diseases. Length, maximum diameter, and minimum diameter of the right adrenal gland and maximum and minimum diameters of the left adrenal gland were significantly greater in dogs with PDH than in healthy dogs and dogs with nonendocrine diseases. As a diagnostic test for PDH, ultrasonographic measurement of maximum or minimum diameter of the left adrenal gland gave the best combination of sensitivity and specificity. For maximum diameter of the left adrenal gland, sensitivity was 77% and specificity was 80%. For minimum diameter of the left adrenal gland, sensitivity was 73% and specificity was 85%.

Ultrasonography of the adrenal glands is a valuable diagnostic procedure in dogs suspected of having pituitary-dependent hyperadrenocorticism.