🐕 Cushing’s Syndrome in Dogs – A 2025 Vet's Guide to Hyperadrenocorticism, Pituitary Tumors, and Steroid Effects

By Dr Duncan Houston, BVSc

🧠 What Is Cushing’s Syndrome?

Cushing’s syndrome, or hyperadrenocorticism, is a condition where the body produces too much cortisol—a vital hormone involved in stress response, metabolism, and immune regulation. While cortisol is essential in short bursts, long-term exposure can lead to serious health issues. 🧬

Most commonly seen in middle-aged and older dogs, the disease often develops slowly, making early detection challenging. Left untreated, it can significantly impact a dog’s comfort and lifespan. 🐾

📉 What Does Cortisol Do?

Produced by the adrenal glands, cortisol helps the body react to stress. It raises blood sugar, mobilizes fat, conserves salt and water, and suppresses the immune system. 🧪

When produced in normal amounts, cortisol prepares the body for short bursts of stress or activity. But if the body is exposed to cortisol constantly—due to internal disease or external steroid use—it results in a prolonged catabolic state, breaking down muscle, thinning skin, and suppressing healing. 💥

🔍 Three Main Causes of Cushing’s Syndrome in Dogs

1. 🧠 Pituitary-Dependent Cushing’s Disease (PDH)

This is the most common cause, responsible for about 85–90% of cases. A small tumor grows in the pituitary gland—usually benign—and overstimulates the adrenal glands via excessive ACTH (adrenocorticotropic hormone) secretion. 💡

This leads to both adrenal glands becoming enlarged and producing too much cortisol. Rarely, the tumor can be large enough to press on the brain and cause neurological symptoms such as confusion, head pressing, or circling. These rare cases involve what are known as pituitary macrotumors. 🧠⚠️

2. ⚖️ Adrenal-Dependent Cushing’s Disease (ADH)

This form involves a tumor directly on one of the adrenal glands, which secretes cortisol independently of pituitary control. About 15% of Cushing’s cases in dogs fall under this category. 🩺

These adrenal tumors may be benign or malignant. The tumor causes one adrenal gland to become enlarged and hyperactive, while the other becomes atrophied due to lack of stimulation. Radiographs or ultrasound usually detect these tumors. 📸

3. 💊 Iatrogenic Cushing’s Syndrome (Steroid-Induced)

This form occurs when a dog receives too many corticosteroids (like prednisone or dexamethasone) over time for other medical conditions—such as allergies, arthritis, or immune disorders. 🐕💉

Excessive steroid use mimics high cortisol levels, so the pituitary gland stops producing ACTH, leading to adrenal gland shrinkage. If steroids are stopped suddenly after long-term use, the dog may not be able to produce natural cortisol, leading to a health crisis. 😬

Important: Always taper off steroid medications gradually under veterinary supervision. 🚫📉

📋 Common Cortisone-Type Drugs That Can Lead to Cushing’s Syndrome

• Prednisone / Prednisolone
• Dexamethasone
• Triamcinolone
• Medrol™ (Methylprednisolone)
• Depo-Medrol
• Azium
• Vetalog

⚠️ Signs of Cushing’s Syndrome

Dogs with Cushing’s often show a slow progression of the following signs:

• 🚰 Excessive thirst and urination
• 🍔 Increased appetite (ravenous behavior)
• 🐖 Pot-bellied or sagging abdomen
• 🐾 Hair thinning or patchy hair loss
• 😴 Lethargy and decreased activity
• 🐶 Panting (even at rest)
• 🔁 Recurring skin infections or slow wound healing

🧪 How Is Cushing’s Syndrome Diagnosed?

Confirming a diagnosis of Cushing’s syndrome often requires multiple steps, including:

• Complete Blood Count (CBC) and Biochemistry Panel
• Urinalysis
• ACTH Stimulation Test
• Low-Dose Dexamethasone Suppression Test (LDDST)
• High-Dose Dexamethasone Suppression Test (HDDST)
• Endogenous ACTH Assay
• Abdominal ultrasound or CT scan

💊 Treatment of Cushing’s Syndrome

🧠 For Pituitary-Dependent Disease

• Trilostane (Vetoryl®) – Most widely used. Suppresses adrenal cortisol production. Requires lifelong use and regular monitoring. 💊
• Mitotane (Lysodren®) – Older, more aggressive. Destroys adrenal cells. 🧨
• Radiation Therapy – For large pituitary macrotumors causing neurological signs. 💡

⚖️ For Adrenal Tumors

• Surgery (Adrenalectomy) – Removes the adrenal gland containing the tumor. Requires advanced imaging and surgical expertise. 🏥

💉 For Steroid-Induced Cushing’s

• Gradual withdrawal of corticosteroids is essential. Never stop suddenly. Tapering schedules should be managed by a vet to restore adrenal function slowly. ⏳

📆 Long-Term Management and Monitoring

Dogs diagnosed with Cushing’s need ongoing care:

• 🔄 Routine ACTH stim tests or cortisol levels
• 📊 Monitoring of electrolytes and liver enzymes
• 📅 Vet check-ups every 3–6 months

📲 Ask A Vet for Support with Cushing’s Care

Cushing’s is a chronic disease, but it’s manageable with the right knowledge and treatment plan. Whether you’re adjusting medication doses, interpreting test results, or wondering about symptoms, the Ask A Vet App is your 2025 solution for real-time, professional guidance. 🐶📱

Visit AskAVet.com or download the app for support from licensed veterinarians who understand the unique needs of dogs living with Cushing’s disease. 🩺🐕‍🦺

✅ Final Takeaways

• Cushing’s syndrome results from chronic cortisol excess 🧬
• Common forms include pituitary and adrenal types, or long-term steroid use 💊
• Diagnosis involves hormone tests and imaging 🧪
• Treatment depends on the cause and may involve meds, surgery, or tapering steroids 🔄
• With proper care, dogs with Cushing’s can live full, happy lives 🐾

💬 Final Words from Dr Duncan Houston

If your dog is showing signs like thirst, hair loss, or weight gain, don’t wait. Early detection of Cushing’s leads to better outcomes. Whether it’s pituitary, adrenal, or medication-related, your vet can guide you to the right solution. 🧠🐶

And remember—Ask A Vet is here when you need expert support, right from your phone. Visit AskAVet.com to get started. 📲🩺