What is Cushing's disease in dogs?

Understanding Cushing's Disease in Dogs

Cushing's disease, medically known as hyperadrenocorticism or Cushing's syndrome, is a fairly common hormonal disorder that affects dogs—especially those entering their golden years. It's all about cortisol: a hormone that's crucial for managing stress, metabolism, immune response, and more. When the body produces too much cortisol over time, things can go awry.

What Causes Cushing's Disease?

There are three main reasons why a dog might develop this condition:

• Pituitary-dependent Cushing's disease: The most frequent culprit (about 80%–90% of cases). It happens when a benign tumor forms on the pituitary gland at the brain's base. This tumor tells the adrenal glands (located near the kidneys) to keep pumping out cortisol nonstop.
• Adrenal-dependent Cushing's disease: Here, a tumor grows directly on one of the adrenal glands—sometimes benign, sometimes malignant—causing it to release too much cortisol.
• Iatrogenic Cushing's disease: This form isn't spontaneous; it occurs when a dog has been given high doses of corticosteroid medications (like prednisone) for an extended period. The drugs mimic cortisol and tip the balance.

Certain breeds—think Poodles, Dachshunds, Yorkshire Terriers, and some small terriers—are more likely to get Cushing’s. Middle-aged and older dogs face higher risks.

Spotting the Symptoms

The signs creep up slowly and can be mistaken for normal aging. Watch for these:

• Drinking and urinating more than usual
• An insatiable appetite
• A pot-bellied look or swollen abdomen
• Thin or fragile skin
• Hair loss or slow hair regrowth
• Panting excessively
• Lethargy or muscle weakness
• Recurring skin infections or wounds that heal slowly
• House soiling in previously trained dogs
• Dark skin patches or blackheads
• Weight gain or odd fat distribution

No two dogs are exactly alike; some show only subtle changes while others display several symptoms at once.

How Is It Diagnosed?

Nailing down a diagnosis isn't always straightforward because many symptoms overlap with other illnesses. Vets usually start with a thorough exam and medical history. Then they’ll run blood and urine tests looking for telltale changes—like high alkaline phosphatase levels or diluted urine.

1. An ACTH stimulation test: Measures how the adrenal glands respond to ACTH by checking cortisol before and after injection.
2. A low-dose dexamethasone suppression (LDDS) test: Assesses if cortisol levels drop appropriately after dexamethasone injection; this helps confirm Cushing’s and sometimes pinpoints its origin.

If needed, vets might use high-dose dexamethasone suppression tests or endogenous ACTH assays to distinguish between pituitary and adrenal causes. Imaging—like ultrasound, X-rays, CT scans, or MRI—can help spot tumors or rule out other issues.

Treatment Options for Dogs with Cushing’s Disease

• If it's pituitary-dependent, lifelong medication is standard. The main drugs are:
  • Trilostane (Vetoryl): Blocks adrenal cortisol production; requires careful dosing and regular monitoring.
  • Mitotane (Lysodren): Destroys part of the adrenal cortex; less common due to side effects but still used in some cases.
  Surgery on pituitary tumors is rare because it's complicated; radiation may be tried if neurological symptoms appear due to large tumors.

• If it's adrenal-dependent, surgery to remove the affected gland can cure some dogs if the tumor hasn't spread. If surgery isn't an option—or if the tumor is malignant—medication similar to pituitary-dependent cases may be used instead.

• If it's iatrogenic Cushing’s, vets will gradually taper off steroid medications while monitoring closely for recurrence of the original problem that prompted steroid use.

No matter which type your dog has, regular checkups are essential. Monitoring includes repeat ACTH stimulation or LDDS tests plus routine bloodwork every few months at first (and then every few months long-term) to ensure medication dosages stay safe and effective.

Lifestyle Management & Prognosis

Cushing’s isn’t usually curable except in certain adrenal or iatrogenic cases—but with proper management most dogs enjoy good quality of life for years after diagnosis. Early treatment helps prevent complications like diabetes mellitus, blood clots, kidney damage, high blood pressure, and chronic infections.

• You'll likely see improvements in your dog's coat quality, energy level, muscle strength—and even their mood—in just weeks to months after starting therapy.

Lifelong medication can be expensive and requires ongoing communication with your vet to adjust dosages as needed. But most owners find their pets happier once symptoms are controlled.

Pitfalls & Complications

If left untreated—or if medication isn’t monitored closely—Cushing’s can cause serious trouble: chronic infections, diabetes mellitus, kidney/liver damage, pancreatitis… even death in severe cases. Side effects from treatment (vomiting, diarrhea, appetite loss) need prompt attention since they could signal dangerous hormone imbalances like Addison’s disease (the opposite problem).

Prevention Tips & Home Care

• You can't prevent most forms since they're caused by spontaneous tumors—but you can avoid iatrogenic Cushing’s by using steroids only when necessary and under close veterinary supervision.

• A balanced diet low in fat may help especially if cholesterol/triglycerides are high.
• Nevr restrict water intake.
• Keenly observe your dog's thirst/appetite/energy between vet visits.
• Diligent home monitoring makes a big difference.

Catching signs early means better outcomes—and more happy years together!