4E—Correct. Although the baseline cortisol concentration is high and greater than 50% cortisol concentration suppression occurred during the test, the eight-hour postdexamethasone administration cortisol concentration is < 2 µg/dl, which is within the reference range. Since the test results are normal, the dog most likely does not have PDH. However, up to 10% of dogs with PDH have normal LDDS test results. Thus, in dogs with clinical signs of hyperadrenocorticism and normal LDDS test results, you may want to perform an ACTH stimulation test next or wait four to six weeks and repeat the LDDS test.
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