Cushing’s Disease in Dogs: A complete Guide

Cushing's disease in dogs. A lab with a blue ball in his mouth rubs his head against his male owner

Cushing’s disease in dogs is one of the more challenging diseases to detect. With most symptoms aligned with an aging dog, it’s easy to consider these signs as nature taking its course.

Thankfully, Cushing’s disease is rare, with less than one percent of dogs diagnosed with this hormone disease. Although certain breeds, like the Bichon Frise, Border Terrier, and Miniature Schnauzers, have increased odds of developing Cushing’s disease.

A quick summary of this article:

What is Cushing’s disease in dogs?

Cushing’s disease (Hyperadrenocorticism) is when excess levels of cortisol — a hormone released by the adrenal gland when stressed — are produced. These excessive cortisol levels cause several negative symptoms in dogs and can be fatal.

What are the symptoms of Cushing’s disease in dogs?

  • Increased water consumption and urination
  • Hair loss
  • Excessive panting
  • Thinning of the skin
  • Increase in appetite
  • Abdominal enlargement
  • Weakening of the heart and muscles
  • Calcified skin lumps (Calcinosis cutis)

If you spot unusual symptoms or changes in your dog’s behavior that cause you to believe they may have Cushing’s disease, these are the tests to help identify the disease:

  • Blood count, urinalysis, and blood chemistry panel
  • Abdominal and adrenal gland ultrasound
  • Dexamethasone suppression test
  • Cortisol to creatinine ratio test

There are several ways to fight Cushing’s disease in dogs. Upon a positive diagnosis, your vet may recommend:

  • Surgery to remove the adrenal tumor and affected adrenal gland
  • A withdrawal of glucocorticoids
  • Medications to suppress cortisol levels

You’ve likely identified symptoms, received a diagnosis, or have been warned of potential Cushing’s disease in your dog since your research brought you here.

By the end of this article, you will have a clear understanding of Cushing’s disease, including the symptoms to watch for, how it’s diagnosed, and the treatments for Cushing’s disease.

  1. What is Cushing’s disease in dogs?
  2. What dogs are at high risk of contracting Cushing’s disease?
  3. Causes of Cushing’s disease in dogs.
  4. What are the main symptoms of Cushing’s disease in dogs?
  5. How is Cushing’s disease diagnosed in dogs?
  6. What are the treatments for Cushing’s disease in dogs?
What is Cushing's Disease in Dogs? A brown dog is examined on the table in a veterinarian's office.

What is Cushing’s disease in dogs?

Cushing’s disease is when the glucocorticoid hormones are at an increased level in your dog’s body.

Also known as hyperadrenocorticism, the increase in glucocorticoid hormones is caused by the adrenal glands’ over-production of cortisol — a steroid hormone that regulates the body’s response to stress. 

Cortisol has many essential functions and is considered the body’s alarm system. For example, cortisol:

  • Regulates blood pressure
  • Reduces inflammation
  • Regulates metabolism
  • Regulates blood sugar
  • Helps in memory formation

Tumors in the adrenal gland — or elsewhere — can cause this over-production of cortisol in the adrenal gland. A tumor in the pituitary gland can secrete a hormone called ACTH — Adrenocorticotropic hormone — which instructs the adrenal glands to produce cortisol.

In addition to a tumor, a defect in the adrenal glands may cause high cortisol levels. However, Cushing’s disease is more commonly related to problems with the pituitary gland and its subsequent secretion of ACTH.

Dogs with Cushing’s disease don’t always show definitive symptoms right away. 

Experts suggest that a dog may show symptoms of this disease up to six years before a positive diagnosis for Cushing’s disease is received. Also, many of the symptoms of Cushing’s disease resemble the signs of aging in dogs (hair loss, muscle weakness, loss of bladder control), so it might not provide an immediate cause for veterinary attention.

What dogs are at high risk of contracting Cushing’s disease?

Cushing’s disease is most commonly seen in middle-aged to older dogs, though a dog as young as two years can contract Cushing’s disease. The median age of affected dogs is 10.9 years.

Studies have shown dogs who have been spayed or neutered are slightly more likely to develop Cushing’s disease. 

Though this disease can affect any dog breed, mixed breeds have the highest risk, followed by the following purebreds: 

  • Border Terrier
  • Bichon Frise
  • Miniature Schnauzer
  • West Highland White Terrier
  • Yorkshire Terrier
  • Lhasa Apso
  • Jack Russell Terrier
  • Boxer

Dog breeds with the lowest risk of Cushing’s Disease are:

  • Cocker Spaniel
  • Labrador Retriever
  • Golden Retriever
  • Rottweiler
  • Border Collie
  • Chihuahua
  • French Bulldog
  • German Shepherd
  • Pug

Pituitary-dependent Cushing’s disease is most common in smaller dog breeds, usually under 45 lbs. In contrast, adrenal-based Cushing’s disease is split evenly between dogs under and over 45 lbs.

How severe is Cushing’s disease?

Due to the improper cortisol balance in a dog’s system, untreated Cushing’s disease can cause severe discomfort for your dog and eventually result in death.

Your dog will essentially become “poisoned” by the excess produced cortisol, as the balance is no longer in effect. 

The pituitary gland and the adrenal glands must function properly to maintain the correct level of secreted glucocorticoid hormones.

What is the life expectancy of a dog with Cushing’s disease?

The survival rate for dogs with Cushing’s disease is high. But, age and health are two major factors to consider when setting expectations.

Furthermore, the type of Cushing’s disease and treatment approach make an impact on survivability.

In a large study of Cushing’s disease survivability in dogs by universities in the UK, 219 cases were followed. The study showed a median survival time from initial diagnosis of 510 days. Dogs over 13 lbs and older than 13 years of age were at the highest risk of mortality.

Dogs with pituitary-dependent disease lived from 662 to 900 days while those treated for adrenal-dependent disease lived between 353 and 475 days.

All dogs were treated with Trilostane, an oral medication and the only FDA approved medication for Cushing’s.

When undergoing surgery for adrenalectomies, a study of 51 dogs showed the short-term survival rate was 92.2%, with 83.3% of dogs surviving one year. The size of the tumor and complexity of the surgery — like a vascular invasion — have a large impact on the outcome.

What is the risk of treating Cushing’s disease?

Depending on your dog’s health and the treatment option you choose, there may be many risks involved when treating Cushing’s disease. 

Since many of the treatment options for Cushing’s disease involve certain chemicals to reestablish a balanced cortisol level, your dog can develop a condition when cortisol levels are too low. 

This condition is called Addison’s disease and is the opposite of Cushing’s disease.

Causes of Cushing's disease in dogs. A pug and a mixed breed akito-inu play on the ground.

Causes of Cushing’s disease in dogs.

There are three leading causes of Cushing’s disease in dogs. Each of these causes requires a different type of treatment approach.

Iatrogenic hyperadrenocorticism

If your dog has allergies or another chronic condition, this condition may require the constant administration of a treatment involving glucocorticoids. Extended glucocorticoid treatments can cause iatrogenic hyperadrenocorticism by producing an excess of corticosteroids that flood your dog’s body. 

The excess cortisol in the body is a reaction almost identical to that of an adrenal tumor.

Even though the pituitary gland will attempt to cut secretion of ACTH, and the adrenal glands will attempt to stop producing so much cortisol, symptoms of Cushing’s disease eventually develop if the glucocorticoid treatment continues. 

If your dog is affected by this cause of Cushing’s disease, your dog’s adrenal glands will be shriveled and atrophied.

Luckily, this is the most treatable type of Cushing’s disease since the glucocorticoid treatment is gradually withdrawn, and the symptoms of Cushing’s disease eventually vanish.

Pituitary-dependent hyperadrenocorticism

Pituitary-dependent hyperadrenocorticism is the most common cause of Cushing’s disease in dogs. Pituitary-dependent hyperadrenocorticism accounts for roughly 85% of all instances of Cushing’s disease in dogs.

Pituitary-dependent Cushing’s disease involves an excess secretion of the hormone ACTH by the pituitary gland. ACTH is what stimulates the adrenal glands to produce more cortisol and other glucocorticoids. 

With this cause, a microadenoma (benign, microscopic tumor) usually forms in the pituitary gland. This tumor outputs excessive amounts of ACTH, which causes the adrenal glands to produce large amounts of cortisol.

Pituitary-dependent hyperadrenocorticism Cushing’s disease in dogs is the most common and easiest to treat. 

The adrenal glands of a dog with Cushing’s disease caused by a pituitary gland tumor will usually be abnormally large since they work hard to produce high cortisol levels in response to the ACTH. Typically, with elevated cortisol levels, the pituitary gland would then stop producing ACTH to halt the production of cortisol. 

However, in pituitary-dependent hyperadrenocorticism, the pituitary gland cannot respond to elevated cortisol levels.

Adrenal-based hyperadrenocorticism

In about 10-15% of instances of Cushing’s disease in dogs, the cause of the hyperadrenocorticism is related to the adrenal gland. 

When an adrenal tumor develops — usually on one of the two adrenal glands — it continues producing cortisol, even if the ACTH hormone levels secreted by the pituitary gland drop. 

An ultrasound of a dog experiencing adrenal-based hyperadrenocorticism will show that one adrenal gland is usually abnormally shaped or extremely large compared to the other adrenal gland.

What are the main symptoms of Cushing’s disease in dogs?

Cushing’s disease symptoms are similar to those in aging dogs, making it a challenging syndrome to detect.

Watching for extremes is the key to identifying Cushing’s versus natural aging.

Increased water consumption and urination

An increase in water consumption is present in about 80-85% of all dogs affected by Cushing’s disease. 

Many dogs with Cushing’s disease will drink anywhere from two to ten times the water they normally drink. This spike in water consumption will increase urination, causing some dogs to lose control of their bladder functions indoors. 

Since this is also a common condition in aging dogs, many people do not see cause for alarm until their dog’s water consumption becomes severely evident.

Hair loss

Hair loss is another visible symptom of Cushing’s disease that usually provokes a dog’s owner to seek veterinary advice. However, hair loss is also a symptom of aging in older dogs, leaving it often unnoticed as a symptom of Cushing’s disease. 

One sign of hair loss caused by Cushing’s disease is that hair loss is usually evenly distributed over both sides of the dog, not in clumps of bare skin.

Excessive panting

Dogs with Cushing’s disease often exhibit symptoms of excessive panting. The increased level of panting may be caused by:

  • Increased fat deposits around the chest and in the abdominal cavity.
  • Increased liver size causes the diaphragm to have a difficult time expanding.
  • Weakening of muscles in the respiratory system due to excessive cortisol levels.

Due to the nature of most dogs to pant, heavy panting may go unnoticed by dog owners.

Thinning of the skin

Many older dogs also experience thinning or “papering” of the skin as they age, so this symptom of Cushing’s disease may also be hard to detect.

Usually, thinning of the skin is accompanied by excessive hair loss, which is a much more visible symptom.

Increase In appetite

Many dogs with Cushing’s disease seem to have an insatiable appetite. They may exhibit new destructive behaviors to consume more food — such as eating garbage or stealing food.

If your older dog begins to eat garbage, steal food, or beg — without changing their diet or exercise — you should consult your veterinarian.

This excessive eating also may contribute to significant weight gain.

Abdominal enlargement

Abdominal distention is a visible symptom of Cushing’s disease caused by your dog’s weakening muscle strength. 

Abdominal enlargement may also be present since dogs with Cushing’s disease may redistribute fat from other storage areas to the abdomen. 

Cushing’s disease can also cause the liver to become enlarged due to the excess cortisol secreted by the adrenal glands. This “potbelly” is usually very prominent in a dog with advanced Cushing’s. 

If your dog is experiencing this symptom, you should take them to the veterinary hospital immediately.

Weakening of the heart and muscles

The weakening of a dog’s muscles because of Cushing’s disease may be present in behaviors such as lethargy, depression, and lack of interest in everyday activities. 

If your dog has Cushing’s disease, they may wobble while walking or seem unable to carry their own weight.

Calcinosis cutis

Calcinosis cutis — also called calcified skin lumps — is a symptom of Cushing’s disease that manifests in mineralized skin nodules. This symptom is not exhibited by all dogs, though it is said to be a textbook sign of Cushing’s disease.

Diagnosing Cushing's Disease in Dogs. An older husky being examined on a vets table.

How is Cushing’s disease diagnosed in dogs?

Your veterinarian has numerous procedures that help diagnose a dog for Cushing’s Disease.

Since the symptoms of Cushing’s disease are relatively generic — and can also be symptoms of many other medical conditions — more than one of these diagnostic procedures may be completed by your veterinarian.

CBC, urinalysis, blood chemistry panel

To begin testing for Cushing’s Disease, your veterinarian will likely complete a CBC, urinalysis, and blood chemistry panel. 

Your veterinarian can detect specific abnormalities in your dog’s body through a CBC (complete blood count), urinalysis, and blood chemistry panel. 

Though not providing a definitive diagnosis, these tests give enough information to warrant further testing. 

For example, a decrease in kidney functions and an increase in cholesterol, alkaline phosphate levels, and liver enzymes are the most common abnormalities detected in dogs with Cushing’s disease. 

Abdominal ultrasound

By using an ultrasound machine, a veterinary technician can study the size and shape of your dog’s internal organs. Also, this ultrasound can examine the state of the adrenal glands.

Depending on the type of Cushing’s disease your dog has, the Adrenal glands may appear slightly different. 

If there is a tumor in the adrenal glands, one adrenal gland will typically appear abnormally shaped or much larger than the other adrenal gland. 

If your dog has pituitary-dependent hyperadrenocorticism, the adrenal glands will usually appear of standard size and shape during the ultrasound procedure. 

Low dose dexamethasone suppression test

In this procedure, your veterinarian provides your dog with several low doses of dexamethasone. After roughly 8 hours, the vet will test the blood cortisol levels. 

When tested, most healthy dogs that are not affected by Cushing’s disease will show a noticeable decrease in blood cortisol levels.

However, a dog with Cushing’s disease will have no change in the blood cortisol levels, even after being given the dexamethasone. 

Since over 90% of dogs with Cushing’s disease will have no response to the dexamethasone, this test is a relatively accurate method for diagnosing Cushing’s disease. 

Urine cortisol: creatinine ratio

Urine Cortisol is a test that starts at home by collecting a sample of your dog’s urine. Since stress levels can cause fluctuations in the results, a comfortable environment, like at home, is best. 

Once the sample is collected and returned to the veterinarian’s office, a specialized laboratory will test the cortisol to creatinine ratio of the dog’s urine. 

If a dog is affected by Cushing’s disease, the result should be abnormal.

However, this is not a definitive diagnosis for Cushing’s disease because several other medical conditions can also cause abnormal cortisol to creatinine ratio.

Treatment for Cushing's disease in dogs. A border collie rests on a brown leather couch covered in a blanket.

What are the treatments for Cushing’s disease in dogs?

Depending on the cause of Cushing’s disease in your dog, several different treatment options are available. 

Treatment for Cushing’s disease is also heavily dependent on how well your dog would be able to handle surgery or other procedures that will put significant stress on their system. 

Some treatment options involve human chemotherapy treatments, which may not be safe for older or ill dogs. The FDA has only approved two drugs to treat Cushing’s disease, Vetoryl and Anipryl.

Withdrawal of glucocorticoids

If your dog has iatrogenic hyperadrenocorticism, treatment is relatively simple. 

Caused by over-administration of glucocorticoids due to treatment of a chronic condition, this type of Cushing’s disease treatment is simple and only involves the gradual withdrawal of the glucocorticoids.

With the subsequent decrease of corticosteroids in your dog’s system, the adrenal glands will eventually begin to function normally once again.

Surgery

Surgery is a treatment reserved for adrenal-based hyperadrenocorticism.

In this treatment procedure, the dog undergoes an operation to remove the adrenal gland tumor and the affected adrenal gland. 

Undergoing surgery can remedy adrenal-based hyperadrenocorticism in most cases since the tumor — if benign — usually doesn’t manifest in the remaining adrenal gland.

However, since one of the symptoms of Cushing’s disease is slow healing of wounds, this procedure must be done with extreme care. 

Your dog may be prescribed Ketoconazole before surgery to help minimize the symptoms of Cushing’s disease.

Adrenal gland tumors are rare in dogs and represent only 0.17% to 0.76% of all tumors. However, malignant tumors can spread to other organs such as the lungs, kidneys, and liver. 

In a study of 51 dogs who underwent adrenalectomies, the short-term survival rate was 92.2%, with 83.3% of dogs surviving one year.

54.9% of dog’s in the study received a diagnosis of a malignant tumor.

Most adrenal tumors aren’t discovered in time to perform surgery, primarily due to the lengthy diagnosis required in most cases of Cushing’s disease. Also, some older dogs may not survive this procedure, so many dog owners choose an alternate form of treatment.

Medication

Oral medications are available to treat your dog’s Cushing’s disease. Depending on which type of Cushing’s or any additional health problems your dog has, veterinarians have options.

Trilostane (brand name Vetoryl)

When needing to treat pituitary and adrenal-dependent Cushing’s in dogs, Trilostane — under the brand name Vetoryl — is the only FDA-approved drug. Vetoryl stops the production of cortisol in the adrenal glands.

Your dog should not receive Vetoryl if they:

  • Suffer from kidney or liver disease
  • Are currently on heart disease medication
  • Are pregnant

The common side effect of Vetoryl is Addison’s disease — an over-suppression of the adrenal glands. The side effects can include:

  • Lethargy and depression
  • Weakness (or collapsing)
  • Diarrhea or loose stools
  • Lack of appetite, not eating
  • Vomiting

Trilostane is the preferred medication of veterinarians to treat Cushing’s disease in dogs.

Mitotane (brand name Lysodren)

A chemotherapy drug, Lysodren is a popular and effective method of treating Cushing’s disease. Doctors prescribe Lysodren “off-label,” meaning not for its intended labeled use.

To treat Cushing’s disease, Lysodren targets the outer layer of the adrenal glands — known as the cortex. 

With regular administration of Lysodren, the cortex tissue of the adrenal gland is gradually destroyed, usually in about a week of daily Lysodren treatments. The damaged adrenals cannot respond as effectively to the over-secretion of ACTH by the pituitary gland, so blood cortisol levels subsequently drop.

After a dog’s blood cortisol levels are within a normal level, they must be given Lysodren for the rest of their lives to maintain their condition. 

The danger with Lysodren is that the adrenals may incur too much damage, which would result in below-normal blood cortisol levels, also known as Addison’s disease.

Ketoconazole

Ketoconazole is a treatment option in dogs that don’t respond to Lysodren treatment. Ketoconazole can be used to treat both adrenal-based and pituitary-dependent hyperadrenocorticism. 

An anti-fungal medication that also suppresses hormone production, Ketoconazole is safer to use than Lysodren. 

In a study of 48 dogs, 90% saw evidence of improvement while being treated for Pituitary-dependent hyperadrenocorticism with Ketoconazole. The median survival time after diagnosis was 25 months.

Anipryl

Anipryl is another FDA approved treatment of Cushing’s disease in dogs. But, Anipryl is reserved only for pituitary-dependent Cushing’s, a less complicated version. 

Anipryl decreases the production of ACTH by increasing levels of dopamine, causing a drop in cortisol levels.

Cushing's disease in dogs. group of five happy dogs border collie sitting on the grass in summer

Final thoughts.

Cushing’s disease is a serious condition all of our dogs can face. Preparing our dogs for the risk is all we can do. This means daily exercise of thirty minutes to one hour, and a healthy diet that includes all-natural healthy snacks.

Additionally, if your dog is a breed at high risk of Cushing’s — like the Bichon Frise, Border Terrier, and Miniature Schnauzer — it’s essential to keep a close watch for typical symptoms as your dog ages.

Symptoms of Cushing’s disease are similar to those of an aging dog and can be challenging to spot. 

Cushing’s disease is survivable. However, the stress and toll it takes on your dog may still shorten their lifespan.

Like every disease, early detection is crucial.

If your dog has Cushing’s Disease, what symptoms first alerted you to contact your veterinarian? Share this post and your story to help others.

This article was originally published on CushingsDiseaseInDogs.org which merged with MyDogIsFat.com. Article was refreshed in 2022 with new sources and updated information.

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