Dog Pituitary-Dependent Hyperadrenocorticism Diagnosis

Accurate diagnosis of the source of Cushing disease guides appropriate treatment selection and avoids unnecessary adrenal surgery.

Key Facts

Pituitary-dependent hyperadrenocorticism (PDH) accounts for 85% of spontaneous Cushing cases; adrenal tumors account for 15%
Distinguishing PDH from adrenal tumor requires abdominal ultrasound and/or HDDS testing
A low-dose dexamethasone suppression test (LDDST) is the most sensitive screening test
High-dose dexamethasone suppression differentiates PDH from adrenal tumor in approximately 75% of cases
Abdominal ultrasound identifies adrenal enlargement - bilateral suggests PDH, unilateral suggests adrenal tumor
Pituitary MRI or CT can identify pituitary macroadenomas that require different management
Medical management with trilostane or mitotane is appropriate for PDH; adrenal tumor may require surgical adrenalectomy

Welfare Considerations

Treating a cat or dog with an adrenal tumor as if they had PDH means giving ineffective medical management while the tumor grows. Accurate source determination ensures the correct treatment is selected promptly, avoiding the welfare harm of progressive disease under inappropriate therapy.

What You Can Do

Request abdominal ultrasound as part of Cushing disease workup - gland imaging guides treatment choice
Discuss HDDS testing with your vet to distinguish PDH from adrenal tumor when screening tests are positive
Seek internal medicine specialist consultation for complex or atypical Cushing presentations
Understand that medical management is appropriate for most PDH cases without pituitary macroadenoma
Follow up with renal function testing during treatment as Cushing masks underlying kidney disease