Dog Cushing's Disease: Signs, Diagnosis & Treatment

Cushing's disease (hyperadrenocorticism) is one of the most common hormonal disorders in dogs, caused by chronically elevated cortisol. The signs develop slowly over months — pot-bellied appearance, excessive drinking and urination, hair loss, and a thin, fragile skin coat — and are easy to dismiss as normal aging. Early diagnosis matters because untreated Cushing's significantly shortens lifespan and predisposes dogs to serious complications including hypertension, blood clots, and diabetes.

Last reviewed: June 2026

What Causes Cushing's Disease in Dogs?

Cortisol is produced by the adrenal glands in response to ACTH (adrenocorticotropic hormone) from the pituitary gland. Cushing's disease occurs when cortisol is produced in excess, and it comes in three forms:

• Pituitary-dependent (PDH): A benign pituitary tumor overproduces ACTH, driving both adrenal glands to overproduce cortisol. This accounts for approximately 80–85% of naturally occurring Cushing's cases in dogs.
• Adrenal-dependent (ADH): A tumor on one adrenal gland autonomously overproduces cortisol, suppressing the pituitary. Accounts for approximately 15–20% of cases. About 50% of adrenal tumors are malignant.
• Iatrogenic Cushing's: Caused by prolonged high-dose steroid (glucocorticoid) medication. The body behaves as though it has Cushing's while on the medication; stopping the drug (gradually) resolves the syndrome.

Breed predispositions are well established. Poodles, Dachshunds, Boxers, Boston Terriers, Beagles, and Yorkshire Terriers are overrepresented. The condition is most common in middle-aged to older dogs, typically presenting between ages 6 and 12, as described in Nelson & Couto's Small Animal Internal Medicine.

Recognizing the Signs of Cushing's Disease

The signs of Cushing's are numerous and affect virtually every body system. They develop gradually, which is why owners often attribute them to old age rather than disease:

Classic signs (present in most cases):

• Polydipsia and polyuria (PU/PD) — drinking and urinating dramatically more than normal; often the first-noticed sign
• Polyphagia — insatiable hunger
• Pot-bellied abdomen — caused by redistribution of fat, weakness of abdominal muscles, and hepatomegaly
• Bilateral symmetric alopecia — hair loss starting on the flanks and trunk, sparing the face and legs
• Thin, fragile skin with visible veins, bruising, and poor healing
• Muscle weakness and exercise intolerance

Less common or secondary signs:

• Calcinosis cutis — calcium deposits visible or palpable under skin
• Recurrent urinary tract infections (in up to 50% of dogs, often asymptomatic)
• Panting — even at rest, due to respiratory muscle effects of cortisol
• Neurological signs if the pituitary tumor is large (rare; macro-adenoma)
• Secondary hypertension affecting eyes, kidneys, and heart

According to the ACVIM Consensus on Cushing's Disease (Behrend et al., 2013, JVIM), the combination of compatible clinical signs plus at least two abnormal screening tests is required before committing to treatment, because false positives from the screening tests alone are common.

Diagnosis

No single test diagnoses Cushing's with certainty. A stepwise approach is used:

Screening tests (used when Cushing's is suspected):

• Urine cortisol-to-creatinine ratio (UCCR): High sensitivity (~99%) but low specificity — many dogs with other illnesses test positive. Used to rule out Cushing's rather than confirm it.
• Low-dose dexamethasone suppression test (LDDST): The most commonly used confirmatory test; sensitivity ~85–95%.
• ACTH stimulation test: Best for diagnosing iatrogenic Cushing's and monitoring treatment response.

Differentiating PDH from ADH:

• High-dose dexamethasone suppression test
• Abdominal ultrasound (asymmetric adrenal enlargement or a distinct mass suggests ADH)
• Endogenous ACTH levels
• CT or MRI to identify pituitary or adrenal masses

Treatment

Pituitary-dependent Cushing's: Oral trilostane (Vetoryl) or mitotane (Lysodren) are the main medical options. Trilostane is currently preferred in most countries due to a more favorable safety profile. Starting doses are adjusted at 10–14 day rechecks using ACTH stimulation testing. Dogs require lifelong medication and regular monitoring. Annual treatment costs for trilostane typically run $500–1,200 depending on dog size and dose.

Adrenal-dependent Cushing's: Surgical adrenalectomy is the treatment of choice for accessible adrenal tumors; referral to a specialist is required. Medical management with trilostane or mitotane is an option for non-surgical candidates.

Iatrogenic Cushing's: Gradual tapering and discontinuation of the causative steroid.

Diagnostic workup — LDDST, ACTH stimulation, abdominal ultrasound, and panels — typically costs $400–900.

When to See a Vet

Call your vet today if:

• Your dog is drinking and urinating significantly more than usual and has a pot-bellied appearance
• Hair loss is symmetrical across the flanks and trunk, with thin or fragile-feeling skin
• Your dog seems exhausted after minimal activity or pants constantly without a clear reason
• Recurrent urinary tract infections or skin infections despite treatment suggest an underlying hormonal cause

Go to the ER immediately if:

• Your dog is on trilostane or mitotane and collapses, is extremely weak, or refuses to eat — adrenal crisis (hypoadrenocorticism from over-suppression) is a medical emergency
• Sudden vision loss or neurological signs (seizures, head pressing, circling) develop — these may indicate a rapidly expanding pituitary tumor

Frequently Asked Questions

How much does diagnosing Cushing's disease cost? Initial bloodwork, urinalysis, and urine cortisol ratio typically run $200–400. A formal LDDST or ACTH stimulation test adds $150–300. Abdominal ultrasound costs $300–600. Total workup to diagnosis often runs $600–1,200 depending on tests required.

Can Cushing's disease in dogs be cured? Pituitary-dependent Cushing's is manageable but typically not cured with medical treatment — dogs remain on medication lifelong. Adrenal-dependent Cushing's can be cured if the tumor is surgically removed and is benign. Pituitary radiation is a curative option in referral centers but is expensive and not widely available.

What happens if Cushing's is left untreated? Untreated Cushing's shortens lifespan. Chronic cortisol excess causes hypertension (present in up to 80% of affected dogs), increased risk of pulmonary thromboembolism, secondary diabetes mellitus, recurrent serious infections, and impaired wound healing. Dogs with untreated Cushing's are also more difficult to anesthetize safely.

Is Cushing's disease painful for dogs? Cushing's itself is rarely painful, but the secondary complications — skin infections, urinary infections, muscle weakness, and hypertension-related organ damage — reduce quality of life substantially. Many owners report dramatic improvement in their dog's energy and well-being within weeks of starting treatment.

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