Cushing’s Disease in Dogs: What It Is and How Vets Treat It

Cushing’s disease in dogs is a hormonal disorder caused by too much cortisol in the body. Common symptoms include increased thirst and urination, increased appetite, excessive panting, hair loss, muscle loss, and a pot-bellied appearance. 

Cushing’s disease—also called hyperadrenocorticism or Cushing’s syndrome—most often affects middle-aged and senior dogs. While most cases require lifelong management, treatment can help control symptoms and maintain a good quality of life. 

What Is Cushing’s Disease in Dogs?

Cushing’s disease in dogs occurs when the body is exposed to excessive amounts of cortisol over time. 

Cortisol is a steroid hormone that plays an important role in metabolism, the stress response, immune function, and other normal body processes. Problems develop when cortisol levels remain too high for too long. 

Two glands are particularly important in Cushing’s disease: 

1. Pituitary gland: Located at the base of the brain, the pituitary gland produces adrenocorticotropic hormone (ACTH), which tells the adrenal glands to produce cortisol.
2. Adrenal glands: Located near the kidneys, the adrenal glands produce cortisol in response to signals from the pituitary gland. 

Normally, the body carefully regulates how much cortisol is produced. With Cushing’s disease, this feedback system is disrupted, resulting in excessive cortisol exposure. 

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Types of Cushing’s Disease in Dogs 

There are two main forms of naturally occurring Cushing’s disease in dogs: pituitary-dependent and adrenal-dependent hyperadrenocorticism. 

A third form, called iatrogenic Cushing’s disease, can develop after prolonged exposure to corticosteroid medications, like prednisone or dexamethasone. 

Pituitary-Dependent Cushing's Disease 

Pituitary-dependent hyperadrenocorticism is the most common form of Cushing’s disease in dogs, comprising around 80–85% of cases. 

It develops when a tumor in the pituitary gland produces too much ACTH. The excess ACTH continually signals the adrenal glands to produce cortisol. 

Advanced imaging such as a CT scan or MRI may be used when veterinarians need to evaluate the pituitary gland, particularly when a larger pituitary tumor is suspected or advanced treatment is being considered. 

Adrenal-Dependent Cushing's Disease 

Adrenal-dependent hyperadrenocorticism occurs when a tumor develops in an adrenal gland and produces excessive cortisol. 

Around half of adrenal tumors are benign (non-cancerous), while the other half are malignant (cancerous).  

Malignant adrenal tumors may invade into nearby tissues or spread to other parts of the body (metastasize).  

Abdominal ultrasound or CT imaging may be used to evaluate the adrenal glands and help determine whether surgery is an appropriate treatment option. 

Symptoms of Cushing’s Disease in Dogs

The most common symptoms of Cushing’s disease in dogs include increased thirst, increased urination, increased appetite, and excessive panting. 

These changes often develop gradually, which means they can initially be mistaken for normal signs of aging. 

Early signs of Cushing’s disease can include: 

• Increased thirst 
• Increased urination or urinary accidents 
• Increased appetite 
• Excessive panting 

Other symptoms can include: 

• Pot-bellied appearance 
• Muscle weakness or muscle loss 
• Lethargy 
• Thinning skin, particularly on the belly and sides 
• Hair loss, usually symmetrically on the trunk of the body 
• Recurring skin infections 
• Calcified or hardened areas of skin, often on the neck, back, armpits, and/or groin 

A dog with Cushing’s disease may appear to gain fat around the abdomen while simultaneously losing muscle elsewhere in the body. 

When Should You Call Your Veterinarian?

Schedule a veterinary appointment if your dog begins drinking or urinating significantly more than usual, develops a noticeably increased appetite, pants excessively without an obvious reason, or develops a combination of skin, coat, muscle, or abdominal changes. 

Measuring your dog’s food and water intake can help you recognize changes and give your veterinarian useful information. 

Vomiting, diarrhea, loss of appetite, marked weakness, collapse, or new neurologic symptoms should not simply be assumed to be Cushing’s disease.  

Contact your veterinarian promptly if your dog develops these signs, particularly if they are already receiving treatment for Cushing’s disease. 

Causes of Cushing’s Disease in Dogs

Cushing’s disease in dogs is most often associated with a pituitary tumor, but adrenal tumors and prolonged exposure to corticosteroid medications can also cause Cushing’s syndrome. 

The main causes include: 

• Pituitary gland tumor: A pituitary tumor produces excessive ACTH, causing the adrenal glands to produce too much cortisol. 
• Adrenal gland tumor: A tumor of an adrenal gland directly produces excessive cortisol. 
• Iatrogenic Cushing’s disease: Long-term or excessive exposure to corticosteroid medications can cause Cushing’s-like symptoms. 

Dogs receiving corticosteroids such as prednisone should never have these medications suddenly stopped unless specifically instructed by their veterinarian.  

When medication is responsible for Cushing’s syndrome, your veterinarian will determine whether and how the corticosteroid can be gradually reduced. 

Cushing’s disease is most often diagnosed in middle-aged and senior dogs. 

Some breeds may also have an increased risk, including: 

• Miniature Poodles 
• Yorkshire Terriers 
• Dachshunds 
• Bichon Frise 
• Lhasa Apso 

How Veterinarians Diagnose Cushing’s Disease

There is no single test that diagnoses every case of Cushing’s disease in dogs. 

Instead, veterinarians consider the dog’s: 

• Symptoms 
• Medical and medication history 
• Physical examination findings 
• Routine blood and urine tests  
• Specialized hormone testing 
• Imaging, like X-rays 

Dogs with Cushing’s disease may have abnormalities such as elevated liver enzymes or cholesterol, changes in blood cell count, or dilute urine. 

If the overall clinical picture suggests Cushing’s disease, specialized testing may include: 

The LDDST is the preferred screening diagnostic for Cushing’s and can sometimes differentiate between pituitary-dependent and adrenal-dependent cases. 

Because stress and other illnesses can affect testing, abnormal results must be interpreted along with the dog’s clinical signs and overall health. 

Low-Dose Dexamethasone Suppression Test 

The low-dose dexamethasone suppression test (LDDST) is commonly used to diagnose Cushing’s disease in dogs. 

A baseline blood sample is taken to measure cortisol. Dexamethasone is then administered, and additional blood samples are collected over several hours. 

In healthy dogs, dexamethasone normally causes cortisol production to decrease. Dogs with Cushing’s disease may not suppress cortisol normally. 

However, no diagnostic test for Cushing’s disease is perfect. Other illnesses and stress can affect results, so veterinarians interpret the LDDST in the context of the dog’s symptoms and other laboratory findings. 

ACTH Stimulation Test 

The ACTH stimulation test evaluates how the adrenal glands respond to ACTH. 

A baseline cortisol sample is collected, ACTH is administered, and another cortisol measurement is taken afterward. 

The ACTH stimulation test may be useful when Cushing’s disease is suspected in certain situations, including suspected iatrogenic disease. It is also used in some monitoring protocols for dogs receiving treatment. 

A normal or abnormal result alone does not always provide the complete answer, so additional testing may be necessary when clinical suspicion remains high.  

This, along with its inability to differentiate pituitary- and adrenal-dependent hyperadrenocorticism, mean the ACTH stimulation test isn’t usually the preferred screening test. 

Additional Diagnostic Tests 

Once Cushing’s disease is confirmed, your veterinarian may recommend additional testing to determine its underlying cause and help guide treatment. 

Tests can include: 

• Abdominal ultrasound 
• CT scan 
• MRI 
• Additional hormone testing 
• Blood work and urinalysis 

Not every dog needs every test.  

Your veterinarian will recommend diagnostics based on your dog’s symptoms, health, test results, and potential treatment options. 

Treatment for Cushing’s Disease in Dogs

Treatment for Cushing’s disease in dogs depends on whether the condition is pituitary-dependent, adrenal-dependent, or caused by corticosteroid medication. 

Many dogs require lifelong treatment and monitoring. The goals are to control the effects of excess cortisol, improve symptoms, and maintain a good quality of life. 

Medications 

Medication is commonly used to manage naturally occurring Cushing’s disease in dogs. 

• Trilostane reduces cortisol production by blocking an enzyme involved in steroid hormone production. It is commonly used to treat dogs with pituitary- or adrenal-dependent Cushing’s disease. 

• Mitotane is another medication that can reduce cortisol production by affecting adrenal tissue and may be used in selected cases. 

Both medications require veterinary supervision and ongoing monitoring because cortisol levels can become too low. This can result in Addison’s disease. 

Never change the dose or frequency of your dog’s Cushing’s medication without speaking with your veterinarian. 

Surgery and Radiation 

Treatment options depend on the type of Cushing’s disease and the individual dog. 

Dogs with adrenal-dependent Cushing’s disease may be candidates for surgery to remove the affected adrenal gland.  

Whether surgery is appropriate depends on factors such as the nature of the tumor (benign versus malignant), whether it has spread or invaded nearby structures, and the dog’s overall health. 

Dogs with pituitary-dependent disease may sometimes be candidates for advanced treatments such as pituitary surgery or radiation therapy.  

These treatments are generally performed at specialty veterinary hospitals. 

Dietary Management 

There is no single diet that cures Cushing’s disease in dogs. 

Dogs should receive a complete and balanced diet appropriate for their age, health, body condition, and any other medical conditions. 

Because some dogs with Cushing’s disease develop elevated cholesterol or triglycerides, a veterinarian may recommend a diet with controlled fat levels.  

Veterinary diets may be appropriate for certain dogs. 

Don’t make major dietary changes or add supplements intended to treat Cushing’s disease without discussing them with your veterinarian. 

Managing Cushing’s Disease in Dogs

Managing Cushing’s disease in dogs requires regular veterinary follow-up and close observation at home. 

Naturally occurring Cushing’s disease generally cannot be prevented because it is associated with pituitary or adrenal disease.  

However, careful veterinary management of long-term corticosteroid therapy can help reduce the risk of medication-induced Cushing’s syndrome. 

Your veterinarian may recommend regular examinations, blood work, hormone testing, and medication adjustments. 

At home, monitor changes in your dog’s: 

• Thirst 
• Urination 
• Appetite 
• Energy 
• Panting 
• Skin and coat 
• Muscle strength 
• Body shape 

If symptoms return or worsen, contact your veterinarian rather than adjusting medication yourself. 

Dogs receiving treatment should also be monitored for signs that cortisol may have become too low. Contact your veterinarian promptly if your dog develops loss of appetite, vomiting, diarrhea, unusual weakness, or lethargy. 

Life Expectancy for Dogs With Cushing's Disease

Many dogs with Cushing’s disease can maintain a good quality of life for months or years with appropriate treatment and monitoring. 

Life expectancy varies significantly from dog to dog and depends on factors including the underlying cause, the dog’s age and overall health, concurrent medical conditions, treatment, and response to therapy. 

Rather than focusing on a single survival estimate, work with your veterinarian to monitor your dog’s comfort, symptoms, treatment response, and overall quality of life.