Cushing's Disease in Dogs: Diagnosis, Management & Care Guide

Disclaimer: This article is intended for informational purposes only and does not constitute veterinary advice. Always consult a qualified veterinarian for diagnosis, treatment, and management of your dog's health conditions.

Watching your beloved dog struggle with unexplained weight gain, excessive thirst, or changes in behavior can be deeply unsettling for any pet owner. One condition that often presents with a constellation of puzzling symptoms is Cushing's disease—also known as hyperadrenocorticism. This endocrine disorder occurs when a dog's body produces too much cortisol, the hormone commonly associated with stress response, metabolism regulation, and immune function. While Cushing's disease is relatively common in middle-aged and older dogs, it can be challenging to recognize because its symptoms often develop gradually and mimic other health issues.

Understanding Cushing's disease is the first step toward ensuring your furry companion receives the care they deserve. From recognizing the early warning signs to navigating diagnostic tests and long-term management strategies, this comprehensive guide will walk you through everything you need to know about Cushing's disease in dogs. Whether your veterinarian has recently raised the possibility of this diagnosis or you simply want to be prepared, the information below will help you become a more informed and proactive advocate for your dog's health and wellbeing.

Understanding Cushing's Disease: Causes and Types

Cushing's disease develops when the adrenal glands—small organs located near the kidneys—produce an excessive amount of cortisol over a sustained period. Cortisol is a vital hormone that helps regulate blood sugar, reduce inflammation, and manage the body's response to stress. However, when cortisol levels remain chronically elevated, it can wreak havoc on nearly every system in a dog's body, leading to the wide-ranging symptoms associated with this condition.

There are three primary types of Cushing's disease in dogs, each with a distinct underlying cause:

Pituitary-Dependent Hyperadrenocorticism (PDH)

This is by far the most common form, accounting for approximately 80 to 85 percent of all naturally occurring cases. PDH is caused by a small, usually benign tumor on the pituitary gland at the base of the brain. This tumor secretes excessive amounts of adrenocorticotropic hormone (ACTH), which signals the adrenal glands to overproduce cortisol. Most pituitary tumors associated with Cushing's disease are microadenomas—tiny growths that rarely cause neurological problems but continuously disrupt hormonal balance.

Adrenal-Dependent Hyperadrenocorticism (ADH)

In roughly 15 to 20 percent of cases, the problem originates directly in one of the adrenal glands. A tumor—either benign (adenoma) or malignant (adenocarcinoma)—develops on one adrenal gland, causing it to pump out cortisol independently of the pituitary gland's signals. Adrenal tumors require different treatment approaches than pituitary-dependent cases, and the prognosis can vary depending on whether the tumor is cancerous.

Iatrogenic Cushing's Syndrome

This form is caused by prolonged administration of corticosteroid medications such as prednisone, dexamethasone, or other steroid-based drugs. Dogs receiving long-term steroid therapy for conditions like allergies, autoimmune diseases, or chronic inflammation may develop iatrogenic Cushing's syndrome. The good news is that this type is often reversible once the medication is gradually tapered under veterinary supervision.

Understanding which type of Cushing's disease your dog has is crucial, as it directly influences the treatment plan and long-term outlook. For more information on common canine health conditions that may interact with or mimic Cushing's disease, explore our health and wellbeing resources for dog owners.

Recognizing the Symptoms of Cushing's Disease in Dogs

One of the most challenging aspects of Cushing's disease is that its symptoms tend to develop slowly over months or even years. Many pet owners initially dismiss early signs as normal aging, which can delay diagnosis and treatment. Being aware of the hallmark symptoms can help you catch the condition earlier and seek veterinary evaluation promptly.

Common Physical Symptoms

• Increased thirst and urination (polydipsia and polyuria): This is often the first symptom owners notice. Dogs with Cushing's disease may drink significantly more water and need to urinate more frequently, sometimes having accidents indoors even if previously house-trained.
• Increased appetite (polyphagia): Elevated cortisol levels can stimulate hunger, leading dogs to eat voraciously, beg for food constantly, or even steal food from counters and trash.
• Pot-bellied appearance: Excess cortisol causes fat redistribution and weakening of the abdominal muscles, giving affected dogs a characteristic rounded, swollen belly.
• Thinning skin and hair loss (alopecia): Cortisol excess leads to fragile, thin skin that may bruise easily. Hair loss typically occurs symmetrically along the trunk, sparing the head and legs, and the remaining coat may appear dull and dry.
• Muscle weakness and wasting: Dogs may lose muscle mass, particularly in the legs, leading to difficulty climbing stairs, jumping, or walking long distances.
• Recurrent skin and ear infections: The immunosuppressive effects of excess cortisol make dogs more susceptible to bacterial and fungal infections.

Behavioral and Secondary Symptoms

• Panting excessively without apparent cause or physical exertion
• Lethargy and reduced activity levels
• Restlessness or difficulty sleeping
• Calcinosis cutis: Hard, calcified deposits that form within the skin, appearing as firm, gritty patches or plaques
• Recurrent urinary tract infections due to immune suppression
• Hypertension (high blood pressure) which may not be visible without veterinary testing

Not every dog will display all of these symptoms, and some may show only subtle changes in the early stages. If you notice any combination of these signs—especially increased thirst, hair loss, and a growing abdomen—it is important to schedule a veterinary appointment. For additional tips on monitoring your dog's health at home, check out our guide to common dog health issues.

How Veterinarians Diagnose Cushing's Disease

Diagnosing Cushing's disease is a multi-step process that requires careful laboratory testing. Because cortisol levels naturally fluctuate throughout the day and can be elevated by stress alone, a single blood test is rarely sufficient. Veterinarians typically use a combination of screening tests and confirmatory tests to build a complete picture.

Initial Screening Tests

Complete Blood Count (CBC) and Biochemistry Panel: While these routine tests cannot definitively diagnose Cushing's disease, they often reveal characteristic patterns such as elevated liver enzymes (particularly alkaline phosphatase or ALP), elevated blood sugar, increased cholesterol, and changes in white blood cell counts. These findings raise suspicion and warrant further investigation.

Urinalysis: A urine sample may show dilute urine and the presence of glucose or protein, which can support the suspicion of hyperadrenocorticism. Urinalysis also helps identify concurrent urinary tract infections, which are common in affected dogs.

Confirmatory Diagnostic Tests

Low-Dose Dexamethasone Suppression Test (LDDST): This is considered one of the most reliable diagnostic tests for Cushing's disease. A baseline blood sample is taken to measure cortisol levels, then a small dose of dexamethasone (a synthetic steroid) is injected. Blood samples are collected at four and eight hours afterward. In healthy dogs, dexamethasone suppresses cortisol production. In dogs with Cushing's disease, cortisol levels remain elevated because the body's feedback mechanisms are disrupted.

ACTH Stimulation Test: This test measures how the adrenal glands respond to an injection of synthetic ACTH. Blood is drawn before and after the injection to measure cortisol levels. Dogs with Cushing's disease typically show an exaggerated cortisol response. This test is also essential for monitoring treatment effectiveness over time.

Urine Cortisol-to-Creatinine Ratio (UCCR): This test measures cortisol levels in a urine sample collected at home, which avoids the stress-related cortisol spikes that can occur during veterinary visits. A normal UCCR effectively rules out Cushing's disease, but an elevated result requires follow-up testing for confirmation.

Differentiating Between Types

Once Cushing's disease is confirmed, additional testing is needed to determine whether it is pituitary-dependent or adrenal-dependent. The High-Dose Dexamethasone Suppression Test (HDDST) can help differentiate between the two: pituitary tumors may partially suppress cortisol production at higher doses, while adrenal tumors typically do not respond at all.

Abdominal ultrasound is another invaluable tool. It allows veterinarians to visualize the adrenal glands directly. In pituitary-dependent cases, both adrenal glands appear enlarged. In adrenal-dependent cases, one gland is enlarged or contains a mass while the other is atrophied (shrunken). Ultrasound can also identify tumors and assess whether they have invaded nearby blood vessels.

In some cases, advanced imaging such as CT or MRI scans of the brain may be recommended to evaluate pituitary tumors, particularly if neurological symptoms are present or if surgical treatment is being considered.

Treatment Options and Long-Term Management

The treatment approach for Cushing's disease depends on the type, the severity of symptoms, and your dog's overall health. Management is typically lifelong and requires close collaboration between you and your veterinarian to ensure the best possible quality of life for your dog.

Medical Management for Pituitary-Dependent Cushing's Disease

Trilostane (Vetoryl): This is the most commonly prescribed and currently the only FDA-approved medication for treating pituitary-dependent Cushing's disease in dogs. Trilostane works by inhibiting an enzyme involved in cortisol production, effectively reducing the amount of cortisol the adrenal glands produce. Most dogs respond well to trilostane, with noticeable improvement in symptoms within a few weeks to months. The medication is typically given once or twice daily with food.

Mitotane (Lysodren): An older treatment option, mitotane works by selectively destroying the outer layers of the adrenal cortex where cortisol is produced. While effective, it requires careful dosing and monitoring because excessive adrenal destruction can lead to Addison's disease (hypoadrenocorticism), a serious condition characterized by dangerously low cortisol levels. Mitotane is used less frequently today but remains an option in certain cases.

Treatment for Adrenal-Dependent Cushing's Disease

Surgical removal (adrenalectomy): If the adrenal tumor is benign and has not spread, surgical removal of the affected adrenal gland can be curative. This is a complex procedure that requires an experienced veterinary surgeon, and post-operative care is intensive. Dogs need temporary cortisol supplementation while the remaining adrenal gland recovers function.

Medical management: If surgery is not an option—due to the tumor being malignant, invasive, or the dog's overall health—trilostane or mitotane may be used to manage cortisol levels and control symptoms. However, the prognosis for malignant adrenal tumors is generally more guarded.

Managing Iatrogenic Cushing's Syndrome

The primary treatment is a gradual, veterinarian-supervised tapering of the corticosteroid medication. Abruptly stopping steroids can cause a life-threatening adrenal crisis, so the dosage must be reduced slowly over weeks or months while monitoring the dog's response. In most cases, symptoms resolve as the medication is withdrawn and the adrenal glands regain normal function.

Ongoing Monitoring and Lifestyle Management

Successful long-term management of Cushing's disease requires regular veterinary follow-up. Here is what ongoing care typically involves:

• Regular ACTH stimulation tests: These are usually performed every few months initially, then every six to twelve months once your dog's condition is stable, to ensure medication dosages remain appropriate.
• Blood work and urinalysis: Routine monitoring helps detect changes in liver enzymes, kidney function, blood sugar, and signs of secondary infections.
• Blood pressure monitoring: Hypertension is a common complication that requires separate management if detected.
• Weight management: As cortisol levels normalize, your dog's appetite and body composition will change. Work with your vet to adjust diet and exercise appropriately.
• Skin and coat care: Hair regrowth can take several months. Gentle grooming and treatment of any secondary skin infections are important during recovery.
• Observation at home: Keep a journal of your dog's water intake, urination frequency, appetite, energy levels, and any new symptoms. This information is invaluable during veterinary appointments.

Learn more about keeping your dog healthy through every stage of life in our senior dog care guide, as many dogs diagnosed with Cushing's disease are in their senior years.

Prognosis, Prevention, and Supporting Your Dog's Wellbeing

While Cushing's disease is a serious condition, the prognosis for dogs with pituitary-dependent hyperadrenocorticism is generally favorable with proper treatment and monitoring. Many dogs live for years after diagnosis with a good quality of life. Dogs with benign adrenal tumors that are successfully removed surgically often have an excellent long-term prognosis. The outlook is more variable for malignant adrenal tumors, and your veterinarian will discuss realistic expectations based on your dog's specific situation.

Can Cushing's Disease Be Prevented?

Unfortunately, naturally occurring Cushing's disease—whether pituitary-dependent or adrenal-dependent—cannot be prevented. The tumors that cause these forms arise spontaneously, and there are no known lifestyle changes or supplements that reduce the risk. However, iatrogenic Cushing's syndrome can be minimized by using corticosteroid medications judiciously and only when necessary, always under close veterinary supervision.

Supporting Overall Wellbeing

Beyond medical treatment, there are many ways to support a dog living with Cushing's disease:

• Balanced nutrition: Feed a high-quality, balanced diet appropriate for your dog's age, size, and health status. Some veterinarians recommend diets lower in fat and moderate in fiber to support metabolic health.
• Consistent routine: Dogs with Cushing's disease benefit from predictable feeding times, medication schedules, and daily routines. Consistency helps reduce stress, which can influence cortisol levels.
• Moderate exercise: Regular, gentle exercise helps maintain muscle tone, supports cardiovascular health, and promotes mental wellbeing. Adjust activity levels based on your dog's energy and comfort.
• Stress reduction: Minimize stressful situations in your dog's environment. Provide a calm, comfortable space for rest and recovery.
• Supplements: Some veterinarians may recommend supplements such as melatonin, lignans, or omega-3 fatty acids to support skin health and overall wellbeing. Always discuss any supplements with your vet before starting them, as they can interact with medications.

For more ideas on enriching your dog's daily life and supporting their emotional health, browse our collection of dog nutrition and wellness articles.

When to See a Veterinarian

Early detection and intervention significantly improve outcomes for dogs with Cushing's disease. You should schedule a veterinary appointment if your dog exhibits any of the following:

• Persistent increase in thirst and urination lasting more than a few days
• Unexplained hair loss, particularly symmetric thinning on the body
• A noticeably enlarging or rounded abdomen
• Increased appetite combined with weight gain or muscle loss
• Recurrent skin infections, ear infections, or urinary tract infections
• Excessive panting without obvious cause
• Lethargy or reluctance to exercise that is unusual for your dog
• Skin that appears thin, fragile, or bruises easily

Seek immediate emergency veterinary care if your dog shows:

• Sudden collapse, extreme weakness, or inability to stand
• Vomiting, diarrhea, or refusal to eat (which could indicate an adrenal crisis, especially if your dog is on medication for Cushing's disease)
• Seizures, disorientation, or other neurological symptoms (which could indicate a large pituitary tumor pressing on brain tissue)
• Severe lethargy or unresponsiveness

If your dog is currently being treated for Cushing's disease, contact your veterinarian promptly if you notice any return of symptoms, new symptoms, or signs that may indicate over-suppression of cortisol (such as vomiting, diarrhea, loss of appetite, or extreme lethargy). Medication dosages often need adjustment, and timely communication with your vet ensures your dog stays on track.

Frequently Asked Questions About Cushing's Disease in Dogs

Is Cushing's disease fatal in dogs?

Cushing's disease is a serious condition, but it is not necessarily fatal when properly managed. With appropriate treatment, regular monitoring, and adjustments as needed, many dogs live for several years after diagnosis with a good quality of life. Untreated Cushing's disease, however, can lead to severe complications including diabetes, kidney disease, hypertension, and life-threatening infections. The prognosis depends on the type of Cushing's disease, the presence of concurrent conditions, and how well the disease responds to treatment. Your veterinarian can provide the most accurate outlook based on your dog's individual circumstances.

What breeds are most prone to Cushing's disease?

Cushing's disease can affect any breed, but it is more commonly diagnosed in certain breeds including Poodles (especially Miniature and Toy Poodles), Dachshunds, Boston Terriers, Yorkshire Terriers, Boxers, and small Terrier breeds. It typically affects middle-aged to older dogs, with most cases diagnosed in dogs between seven and twelve years of age. Female dogs appear to be slightly more predisposed than males. However, because Cushing's disease has been documented in virtually every breed and in mixed-breed dogs, no dog is entirely exempt from risk.

Can diet or supplements cure Cushing's disease?

No diet or supplement can cure Cushing's disease. While proper nutrition and certain supplements may support overall health and help manage some symptoms, medical treatment with prescription medications like trilostane remains the standard of care for pituitary-dependent Cushing's disease. Some holistic practitioners recommend supplements such as melatonin or flaxseed lignans to help modulate hormone levels, but scientific evidence supporting their efficacy is limited. Always discuss any dietary changes or supplements with your veterinarian before introducing them, as they can interact with prescribed medications or affect monitoring tests.

How long does it take for treatment to work?

The timeline for improvement varies depending on the individual dog and the specific symptoms. Many owners notice a reduction in excessive thirst and urination within the first one to four weeks of starting trilostane. Appetite may normalize within a similar timeframe. Hair regrowth and skin improvements typically take longer—often two to six months—as the skin and coat need time to regenerate. Muscle tone and abdominal appearance may improve gradually over several months. Full stabilization of all symptoms can take three to six months, and medication dosages may need to be adjusted multiple times during this period based on follow-up testing.

What happens if Cushing's disease is left untreated?

Without treatment, Cushing's disease progressively worsens over time. Chronically elevated cortisol levels suppress the immune system, making dogs vulnerable to serious and recurrent infections. The condition increases the risk of developing diabetes mellitus, hypertension, kidney damage, blood clots (pulmonary thromboembolism), and congestive heart failure. Muscle wasting becomes more severe, skin becomes increasingly fragile, and the dog's overall quality of life declines significantly. In advanced cases, untreated Cushing's disease can be life-threatening. Early diagnosis and consistent treatment are essential for preventing these complications and giving your dog the best chance at a long, comfortable life.

If you suspect your dog may have Cushing's disease or have questions about managing an existing diagnosis, do not hesitate to reach out to your veterinarian. With the right medical care and your attentive support at home, dogs with Cushing's disease can continue to enjoy happy, fulfilling lives alongside the families who love them. For more resources on caring for your canine companion, visit our complete guide library at Paws & Tales.