Cushing's Disease in Dogs (Hyperadrenocorticism)
Caused by chronic excess cortisol production, most often from a pituitary tumor, and one of the most common endocrine diseases in middle-aged to older dogs.
Overview
Cushing's disease results from chronic overproduction of cortisol. Around 80-85% of cases are pituitary-dependent (a small pituitary tumor drives excess ACTH), while the remainder are adrenal-dependent (a tumor in one adrenal gland).
Clinical signs
- Polyuria and polydipsia
- Polyphagia
- A pot-bellied abdominal appearance
- Symmetric hair loss on the trunk and thin skin
- Muscle weakness, lethargy, and increased susceptibility to infections
Diagnosis
- Screening with an ACTH stimulation test or low-dose dexamethasone suppression test
- Abdominal ultrasound to help distinguish pituitary-dependent from adrenal-dependent disease and assess adrenal gland size
- Endogenous ACTH level to further localize the source in select cases
Treatment
- Trilostane, the most commonly used medication, which requires regular monitoring with ACTH stimulation tests to guide dosing
- Mitotane as an older alternative medication
- Adrenalectomy for appropriate adrenal tumor cases
- Radiation therapy considered for pituitary macrotumors causing neurologic signs
Prognosis
Good quality of life is achievable with appropriate medical management and monitoring in most cases. Prognosis varies with the underlying cause and, for adrenal tumors, whether the tumor is benign or malignant.
This page is general reference information for educational purposes. It is not a substitute for an individual clinical assessment, current formulary guidance, or the judgment of a licensed veterinarian treating a specific patient.
Frequently asked questions
Is Cushing's disease in dogs curable?
Medical management (the most common approach) controls the condition rather than curing it, and is typically lifelong. Adrenal tumors that are surgically removed can sometimes be curative, depending on the case.
Why does my dog need frequent blood tests on trilostane?
Trilostane dosing is individualized and can change over time. ACTH stimulation testing shows how well the current dose is controlling cortisol, which helps avoid both under- and over-treatment.