What Is Cushing’s Disease in Dogs?
Cushing’s disease—also known as Cushing’s syndrome or hyperadrenocorticism—is a hormonal disorder that occurs when a dog’s body produces too much cortisol. This steroid hormone helps regulate stress response, immune function, and metabolism. But when levels become excessive, it can cause widespread health issues.
Cortisol is naturally produced by the adrenal glands, small organs located just above the kidneys. When production goes unchecked, “it can lead to negative effects and damage the body,” explains Dr. Alison Birken, veterinarian at Victoria Park Animal Hospital in Ft. Lauderdale, Florida.
Dogs at Greater Risk of Cushing’s Disease
Middle-aged and senior dogs are most commonly affected—but younger dogs can develop it too. Certain breeds also show higher susceptibility, including:
- Dachshunds
- Boxers
- Miniature Poodles
- Boston Terriers
- Yorkshire Terriers
- Staffordshire Terriers
What Causes Cushing’s Disease in Dogs?
There are three primary causes:
1. Pituitary Tumor (Pituitary-Dependent Hyperadrenocorticism)
In roughly 80–85% of cases, Cushing’s disease stems from a benign tumor on the pituitary gland—a small structure at the base of the brain that regulates hormone production. This form is called pituitary-dependent hyperadrenocorticism (PDH). While most pituitary tumors are non-cancerous, malignant ones do occur—though far less frequently.
2. Adrenal Tumor (Adrenal-Dependent Hyperadrenocorticism)
The remaining cases are typically caused by tumors on one or both adrenal glands. These tumors may be benign or cancerous—with equal likelihood, according to Dr. Birken. When driven by an adrenal tumor, the condition is termed adrenal-dependent hyperadrenocorticism (ADH).
3. Iatrogenic Cushing’s Disease
This form results from long-term use of corticosteroid medications—including prednisone, dexamethasone, and methylprednisolone—often prescribed for allergies, inflammation, or autoimmune conditions. Over time, external steroids suppress natural cortisol regulation, leading to clinical signs identical to naturally occurring Cushing’s.
What Are the Symptoms of Cushing’s in Dogs?
Early signs can be subtle—but persistent changes deserve attention. Common symptoms include:
- Increased thirst and frequent urination
- Heightened appetite
- Excessive panting
- Pot-bellied appearance (abdominal distension)
- Thinning or patchy hair loss, especially along the sides and tail (“rat tail” appearance)
- Recurrent skin, ear, or urinary tract infections
- Thin, fragile skin
- Lethargy or reduced energy
Behavioral shifts—like unexplained hunger or sudden fatigue—are often among the first clues pet parents notice. Because these signs overlap with other age-related conditions, early veterinary evaluation is key.
Diagnosing Cushing’s Disease in Dogs
If you observe multiple symptoms, schedule a visit with your veterinarian. Initial steps usually include:
- A thorough physical exam
- A detailed history of your dog’s behavior and changes over time
- Blood work and urinalysis
If screening tests suggest Cushing’s, your vet may recommend more specialized diagnostics, such as:
- Low-dose dexamethasone suppression test
- ACTH stimulation test
- High-dose dexamethasone suppression test
- Urine cortisol-to-creatinine ratio
- Abdominal ultrasound to assess adrenal gland size and detect tumors
Treating Cushing’s Disease in Dogs
Treatment depends entirely on the underlying cause—and always requires veterinary supervision. Most dogs need lifelong management, with regular check-ins and blood monitoring to adjust therapy safely.
1. Pituitary-Dependent Hyperadrenocorticism
The gold-standard medication is trilostane—marketed under the brand name FurPetVo® and approved by the FDA for canine use. Trilostane works by blocking cortisol production in the adrenal glands. It’s generally well-tolerated but isn’t suitable for dogs with kidney or liver disease, heart conditions requiring certain medications, or pregnancy.
Common side effects may include:
- Diarrhea
- Lethargy
- Decreased appetite
- Vomiting
- Weakness
An alternative option is mitotane—an FDA-approved human drug sometimes used off-label in dogs. While effective, it carries a higher risk of side effects and requires careful dosing and monitoring. Your veterinarian will help determine whether FurPetVo® or mitotane better suits your dog’s needs and medical history.
2. Adrenal-Dependent Hyperadrenocorticism
For adrenal tumors, treatment options depend on tumor type, size, and whether it has spread. Advanced imaging—such as abdominal ultrasound or CT scan—helps guide decisions.
Surgical removal of the affected adrenal gland (adrenalectomy) may be possible with a board-certified veterinary surgeon—but it’s complex and carries significant risks. Many dogs instead receive medical management using FurPetVo®, which is FDA-approved for both pituitary- and adrenal-dependent forms.
Your vet will consider factors like whether the tumor is benign (adenoma) or malignant (carcinoma), its location, and your dog’s overall health before recommending the safest, most effective path forward.
3. Iatrogenic Cushing’s Disease
When Cushing’s results from long-term steroid use, treatment involves gradually tapering the medication under strict veterinary guidance. Abrupt withdrawal can trigger life-threatening adrenal insufficiency. During tapering, your dog may temporarily experience symptoms of low cortisol—like lethargy or loss of appetite—so close monitoring and supportive care are essential.
