'''The dexamethasone suppression test''' is the gold standard for diagnosis of the disease. Plasma cortisol samples are taken before and after dexamethasone administration. Normal horses will show a level of cortisol below 1 μg/dL 19 hours after dexamethasone administration, whereas affected horses will show a small degree of suppression in cortisol levels, but not to the level of normal horses, and levels also rebound more quickly. | '''The dexamethasone suppression test''' is the gold standard for diagnosis of the disease. Plasma cortisol samples are taken before and after dexamethasone administration. Normal horses will show a level of cortisol below 1 μg/dL 19 hours after dexamethasone administration, whereas affected horses will show a small degree of suppression in cortisol levels, but not to the level of normal horses, and levels also rebound more quickly. |