What Is Cushing’s Disease in Dogs?
Cushing’s disease, known medically as hyperadrenocorticism, occurs when a dog’s body produces too much cortisol, the stress hormone. Cortisol plays important roles in managing weight, blood sugar, immune response, and stress reactions, but when the adrenal glands produce it in excess, it damages nearly every system in the body. Understanding dog cushing disease signs helps you catch this condition early, when treatment is most effective.
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Cushing’s disease primarily affects middle-aged and older dogs, typically those over six years old. Certain breeds including Poodles, Dachshunds, Beagles, Boston Terriers, and Boxers are predisposed, though the condition can develop in any breed. It is one of the most commonly diagnosed endocrine disorders in dogs.
Three Types of Cushing’s Disease
Cushing’s disease in dogs has three distinct causes, and identifying the type is essential for choosing the right treatment approach.
Pituitary-dependent Cushing’s (PDH): This is the most common form, accounting for about 80 to 85 percent of cases. A benign tumor on the pituitary gland at the base of the brain overproduces adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce excess cortisol. Most pituitary tumors are small and slow-growing.
Adrenal-dependent Cushing’s: In about 15 to 20 percent of cases, a tumor on one of the adrenal glands (located near the kidneys) directly produces excess cortisol. These tumors can be benign (adenoma) or malignant (carcinoma). Adrenal tumors are sometimes removable through surgery.
Iatrogenic Cushing’s: This form results from long-term administration of corticosteroid medications like prednisone. The external steroids mimic cortisol’s effects, creating the same symptoms as the disease itself. Iatrogenic Cushing’s resolves when the medication is gradually tapered under veterinary supervision; abrupt discontinuation is dangerous.
Recognizing Dog Cushing Disease Signs
The symptoms of Cushing’s disease develop gradually, which is why many owners initially attribute them to normal aging. The most common dog cushing disease signs include:
Increased thirst and urination (polydipsia and polyuria): This is often the first symptom owners notice. Dogs may drink two to three times their normal water intake and need to urinate far more frequently, sometimes having accidents indoors after years of reliable house training.
Increased appetite (polyphagia): Excess cortisol drives intense hunger. Your dog may beg for food constantly, eat faster than usual, scavenge, or attempt to eat non-food items. This ravenous appetite is a hallmark of Cushing’s disease.
Pot-bellied appearance: Cortisol causes fat redistribution to the abdomen and weakens the abdominal muscles, creating a distinctive pendulous belly. This is often mistaken for simple weight gain or bloating.
Hair loss (alopecia): Bilateral, symmetrical hair loss along the flanks, back, and tail is characteristic of Cushing’s disease. The skin beneath may become thin, darkly pigmented, and prone to bruising. Unlike allergy-related hair loss, Cushing’s-related alopecia is typically non-itchy.
Skin changes: Thin, fragile skin that tears easily, recurrent skin infections, blackheads (comedones), and slow wound healing are common. Calcinosis cutis, a condition where calcium deposits form in the skin, can occur in severe cases.
Lethargy and muscle weakness: Excess cortisol breaks down muscle tissue over time, leading to weakness, exercise intolerance, and difficulty climbing stairs or jumping onto furniture. Your active dog may become reluctant to walk as far or play as energetically.
Panting: Excessive panting, even at rest or in cool environments, occurs because cortisol affects respiratory muscle strength and fat distribution around the chest.
Diagnosis: Testing for Cushing’s Disease
Diagnosing Cushing’s disease requires specific hormonal tests because routine blood work may suggest the condition but cannot confirm it. If your veterinarian suspects Cushing’s based on symptoms and initial lab work, they will recommend one or more of the following tests.
Urine cortisol:creatinine ratio (UCCR): This simple urine test screens for Cushing’s disease. A normal result effectively rules out the condition. An elevated result warrants further testing, as other illnesses can also raise urine cortisol levels.
Low-dose dexamethasone suppression test (LDDS): This is the most commonly used confirmatory test. A small dose of dexamethasone is injected, and cortisol levels are measured at four and eight hours. In healthy dogs, dexamethasone suppresses cortisol production. In dogs with Cushing’s, cortisol levels remain elevated. The LDDS test can also help distinguish between pituitary and adrenal causes in some cases.
ACTH stimulation test: This test measures how the adrenal glands respond to synthetic ACTH. It is the preferred test for diagnosing iatrogenic Cushing’s and for monitoring treatment response once therapy begins. Results are available within a few hours.
Abdominal ultrasound: Imaging the adrenal glands helps identify tumors and assess gland size. Symmetrically enlarged glands suggest pituitary-dependent disease, while asymmetric enlargement (one large, one small) points toward an adrenal tumor.
Advanced imaging (CT or MRI): If a pituitary tumor is suspected and surgery or radiation therapy is being considered, advanced imaging of the brain provides detailed information about tumor size and location.
Treatment Options
Treatment depends on the type of Cushing’s disease and the overall health of your dog. The goal is to reduce cortisol levels to a normal range while minimizing side effects.
Medical Management
Trilostane (Vetoryl): This is the most commonly prescribed medication for both pituitary and adrenal-dependent Cushing’s disease. Trilostane inhibits cortisol production in the adrenal glands. It requires careful dose adjustments and regular ACTH stimulation tests (initially every two to four weeks, then every three to six months) to ensure cortisol levels stay in the therapeutic range. Side effects include lethargy, decreased appetite, vomiting, and in rare cases, adrenal necrosis.
Mitotane (Lysodren): An older medication that selectively destroys cortisol-producing adrenal tissue. Mitotane is effective but has a narrower safety margin and requires close monitoring. It is used less frequently since trilostane became available but remains an option for cases that do not respond to trilostane.
Surgery
Adrenalectomy (surgical removal of the affected adrenal gland) can be curative for adrenal-dependent Cushing’s disease if the tumor is benign and has not spread. This is a complex surgery that should be performed by a veterinary surgeon experienced with adrenal surgery. Pituitary surgery (transsphenoidal hypophysectomy) is available at select veterinary teaching hospitals but is not widely performed.
Radiation Therapy
For pituitary tumors, especially larger ones causing neurological symptoms, radiation therapy can shrink the tumor and improve clinical signs. This is typically available at veterinary specialty hospitals and university teaching hospitals.
Living With a Dog With Cushing’s Disease
With proper treatment and monitoring, many dogs with Cushing’s disease live comfortably for years after diagnosis. Here is what day-to-day management looks like.
Provide unlimited access to fresh water. Dogs on Cushing’s medication still drink more than average, and restricting water causes dangerous dehydration. Expect more frequent potty breaks, and consider installing a dog door or adjusting your schedule to accommodate increased urination.
Feed a consistent, high-quality diet. Some veterinarians recommend a moderate-protein, low-fat diet for dogs with Cushing’s, but individual recommendations vary. Avoid high-sodium treats and maintain portion control to manage weight.
Monitor for signs of over-treatment. If cortisol drops too low (hypoadrenocorticism or Addisonian crisis), your dog may show lethargy, weakness, vomiting, diarrhea, or collapse. This is a medical emergency. Know the signs and have your veterinarian’s emergency number readily available.
Keep regular veterinary appointments. Monitoring blood work and ACTH stimulation tests are essential for safe medication management. Do not adjust doses on your own. For more on managing chronic health conditions in dogs, explore our dog adoption hub and related care guides.
Frequently Asked Questions
Is Cushing’s disease painful for dogs?
Cushing’s disease itself is not typically painful, but the secondary effects, including skin infections, muscle weakness, urinary tract infections, and calcinosis cutis, can cause discomfort. Managing these secondary conditions alongside the primary disease is an important part of your dog’s care plan.
How long can a dog live with Cushing’s disease?
With treatment, many dogs live two to four years or more after diagnosis. Dogs with pituitary-dependent Cushing’s that respond well to medication often enjoy a good quality of life for a significant period. Prognosis for adrenal tumors depends on whether the tumor is benign or malignant and whether surgery is an option. Consult your veterinarian for a prognosis specific to your dog’s situation.
Can Cushing’s disease be cured?
Adrenal-dependent Cushing’s can potentially be cured through surgical removal of the adrenal tumor. Pituitary-dependent Cushing’s is typically managed (not cured) with lifelong medication. Iatrogenic Cushing’s resolves when the causative steroid medication is gradually discontinued. See our senior dog care resources for more on managing age-related conditions.
What happens if Cushing’s disease is left untreated?
Untreated Cushing’s disease progressively damages the body. Chronic excess cortisol increases the risk of diabetes, pancreatitis, blood clots (pulmonary thromboembolism), recurrent infections, and organ damage. Quality of life deteriorates as muscle wasting, skin problems, and lethargy worsen. Early treatment significantly improves outcomes and comfort.
Is Cushing’s disease hereditary?
There is a breed predisposition suggesting a genetic component, but Cushing’s disease is not directly inherited in a simple genetic pattern. Breeds like Poodles, Dachshunds, Beagles, and Boxers are at higher risk, but any dog can develop the condition. Awareness of breed predisposition helps owners and veterinarians pursue earlier screening when suggestive symptoms appear.
