Cushing's Disease in Dogs: Symptoms, Treatment & Management Guide

What is Cushing's Disease?

Cushing's disease, or hyperadrenocorticism, is a condition where the body produces excessive amounts of cortisol, a stress hormone. It is one of the most common endocrine disorders in dogs. Cortisol is produced by the adrenal glands and helps regulate metabolism, immune response, and stress.

Two Main Types

Pituitary-Dependent Cushing's (PDH): 80-85% of cases. A benign pituitary tumor produces excess ACTH, which stimulates the adrenal glands to overproduce cortisol.

Adrenal-Dependent Cushing's (ADH): 15-20% of cases. An adrenal gland tumor (benign or malignant) directly produces excess cortisol.

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Symptoms

Classic Signs

• Increased thirst and urination (polyuria/polydipsia) - most common
• Increased appetite (polyphagia)
• Pot-bellied appearance (abdominal muscle weakening)
• Hair loss (bilaterally symmetrical, non-itchy)
• Thin skin and easy bruising
• Lethargy and exercise intolerance
• Panting (excessive)

Additional Signs

• Recurrent urinary tract infections
• Skin infections and slow healing
• Muscle weakness and wasting
• Weight gain or redistribution
• Darkening of skin (hyperpigmentation)
• Calcium deposits in skin (calcinosis cutis)

Severe Cases

• High blood pressure
• Diabetes mellitus (can develop secondary)
• Blood clots (pulmonary thromboembolism)
• Heart failure

Who Is at Risk?

• Older dogs (average age 6-10 years)
• Small breed dogs: Poodles, Dachshunds, Terriers, Beagles
• Large breed dogs (for adrenal tumors): Boxers
• Dogs treated with steroids long-term (iatrogenic Cushing's)

Diagnosis & Costs

Screening Tests

• CBC: $80-150 (stress leukogram, thrombocytosis)
• Chemistry panel: $120-250 (elevated liver enzymes, cholesterol)
• Urinalysis: $60-120 (dilute urine, possible UTI)
• Urine cortisol:creatinine ratio: $80-150 (screening only)

Confirmatory Tests

• Low-Dose Dexamethasone Suppression (LDDS): $150-300 (most reliable)
• ACTH Stimulation Test: $150-300 (alternative confirmatory)
• High-Dose Dexamethasone Suppression: $150-300 (distinguishes PDH vs ADH)

Imaging

• Abdominal ultrasound: $250-500 (identify adrenal tumor vs bilateral enlargement)
• CT or MRI (if pituitary tumor suspected): $1,000-$2,500

Total Diagnostic Cost: $500-2,500

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Treatment

For Pituitary-Dependent Cushing's (PDH)

Trilostane (Vetoryl) - Most common treatment:

• Cost: $60-150/month
• Dosing: Once or twice daily capsules
• Monitoring: ACTH stimulation test every 2-4 weeks initially, then every 3-6 months
• Monitoring cost: $150-300 per test
• Annual cost: $1,200-3,000

Mitotane (Lysodren) - Older alternative:

• Cost: $40-100/month
• Higher risk of side effects
• Requires careful monitoring

For Adrenal-Dependent Cushing's (ADH)

Surgical removal of adrenal tumor:

• Cost: $2,000-$5,000
• Risks: Anesthesia, post-operative complications
• Cure rate: 50-80% if tumor is benign and fully removed

Trilostane (if surgery not an option):

• Same as PDH treatment

Total Treatment Cost

• First year (PDH): $2,000-$5,000 (diagnosis + treatment + monitoring)
• Ongoing annual: $1,200-$3,000
• Adrenal tumor surgery: $2,000-$5,000

Monitoring

On Trilostane

• ACTH stimulation test: 10-14 days after starting, then every 4 weeks until stable
• Quarterly monitoring once stable
• Watch for: Lethargy, vomiting, diarrhea (signs of overdosage)

Annual Monitoring

• ACTH stimulation: $150-300
• CBC and chemistry: $150-300
• Urinalysis: $60-120

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Complications

Untreated Cushing's

• Diabetes mellitus (secondary)
• Hypertension and heart disease
• Pulmonary thromboembolism (blood clots in lungs)
• Skin infections and slow wound healing
• Muscle weakness and exercise intolerance
• Reduced quality of life and shortened lifespan

Treatment Complications

• Addisonian crisis (over-treatment leading to cortisol deficiency)
• Gastrointestinal upset from medication
• Drug interactions with other medications

Prognosis

• With treatment (PDH): Good - most dogs live 2-4+ years with good quality of life
• With surgery (ADH, benign): Excellent - potential cure
• Untreated: Progressive deterioration, fatal within 1-3 years
• Malignant adrenal tumor: Guarded, may metastasize to liver and lungs

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Related: diabetes, hypothyroidism, skin-allergies