Cushing's Disease in Dogs

Your veterinarian may call it hyperadrenocorticism. That is the long medical name you may see on your dog's paperwork, but it simply means there is too much cortisol affecting the body.

Think of It as the Body Being Stuck in Stress Mode

Cortisol is often called the stress hormone.

Your dog needs cortisol. It helps the body respond to illness, injury, fear, and other stressful situations. It also affects blood sugar, inflammation, blood pressure, the immune system, and many other everyday functions.

The problem is not that cortisol is bad.

The problem is having too much of it, day after day.

I tell people to imagine that their dog's body thinks it is always in some version of fight-or-flight mode. The dog may be lying comfortably on the couch, but inside the body, the stress system never fully turns off.

Eventually, that constant exposure begins affecting almost every part of the body.

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Why Does the Body Make Too Much Cortisol?

Your dog has two small glands located near the kidneys. These glands make cortisol.

There are three main reasons they may produce—or appear to produce—too much.

The brain keeps sending the wrong message

Most dogs with Cushing's have a very small growth in a gland at the base of the brain. This gland works like a control center and tells the adrenal glands how much cortisol to make.

The growth is often not cancerous, but it keeps sending the message:

"Make more cortisol."

The adrenal glands are simply following those instructions.

An adrenal gland starts working on its own

Some dogs have a growth on one of the adrenal glands near the kidneys.

Instead of waiting for instructions from the brain, that gland starts making cortisol on its own. These growths can be noncancerous or cancerous, so an ultrasound or another scan may be recommended to learn more.

Steroid medication causes the same changes

Cushing's can also develop after prolonged use of steroid medication.

Steroids may be given as pills, injections, creams, ear medications, eye medications, or products placed on the skin. These medications can be extremely useful and sometimes lifesaving, but long-term use can produce the same effects as having too much natural cortisol.

Never stop a steroid medication suddenly unless your veterinarian tells you to. The dose may need to be reduced gradually so the body has time to adjust.

What Signs Do Owners Usually Notice?

Cushing's usually develops slowly. You may not see one dramatic change. Instead, you may notice several smaller changes that gradually become more obvious.

Your dog may:

• Drink much more water than usual
• Need to urinate more frequently
• Wake you during the night to go outside
• Begin having accidents in the house
• Act hungry all the time
• Pant even when it is not particularly hot
• Develop a round or sagging belly
• Lose muscle, especially in the back legs
• Have trouble standing up or climbing stairs
• Develop thin skin or areas of hair loss
• Have skin infections that keep returning
• Develop repeated urinary infections
• Seem tired or less active

Many owners initially believe these changes are a normal part of aging.

That is understandable because Cushing's most commonly affects middle-aged and older dogs. But constantly emptying the water bowl, waking up several times during the night, or suddenly acting ravenously hungry should not automatically be blamed on age.

Those changes deserve a veterinary examination.

Do These Signs Automatically Mean Cushing's?

No.

Diabetes, kidney disease, liver problems, urinary infections, medication side effects, and other conditions can produce similar signs. A dog can also have more than one medical problem at the same time.

That is why we should not diagnose Cushing's based only on symptoms or one abnormal value on routine bloodwork.

Before special testing, your veterinarian will usually consider:

• What changes you have noticed at home
• How long those changes have been happening
• Every medication and supplement your dog receives
• Findings from the physical examination
• Routine blood and urine results
• Whether another illness could be causing similar changes

Special testing is most useful when the symptoms, examination, and routine laboratory results already point toward Cushing's.

The Low-Dose Dexamethasone Suppression Test

One of the most common tests used to diagnose Cushing's is called the low-dose dexamethasone suppression test, or LDDST.

The name sounds intimidating, but the basic idea is not.

Your dog's cortisol level is checked before the test begins. A very small amount of a steroid is then given through a vein.

In a dog without Cushing's, the brain should recognize that steroid and tell the body:

"We have enough. You can stop making cortisol now."

A dog with Cushing's may not respond appropriately to that stop signal. The body may continue producing cortisol when it should have slowed down.

Blood is generally collected before the injection and again several hours later. Because the final sample is usually collected about eight hours after the test begins, your dog may need to spend most of the day at the veterinary hospital.

The test can help support a diagnosis and, in some dogs, may provide clues about where the problem is coming from.

However, it is not perfect.

Stress and other illnesses can affect the results. Sometimes the test is negative even though Cushing's is still strongly suspected. Sometimes it appears positive when another health problem is affecting the dog.

Your veterinarian may recommend repeating the test, performing a different test, or waiting until another illness has been treated.

This is one reason diagnosing Cushing's can feel slow and frustrating. A gray-area result does not necessarily mean the test was performed incorrectly. Cushing's can genuinely be difficult to confirm.

The ACTH Stimulation Test

Another test you may hear about is the ACTH stimulation test.

This test is commonly used after treatment begins to help determine how strongly the adrenal glands can still respond.

A blood sample is collected to measure cortisol. Your dog then receives an injection that acts like the body's natural "make cortisol" signal. Another blood sample is collected afterward.

We compare the two samples to see how the adrenal glands responded.

When a dog is taking medication for Cushing's, this test can help us make sure treatment has not lowered cortisol too far. Lowering cortisol too much can make a dog seriously ill.

The test result is only one part of monitoring. How your dog feels at home is just as important—and often more important—than a single number.

Your veterinarian will want to know:

• Is your dog drinking less?
• Is your dog urinating less frequently?
• Has the constant hunger improved?
• Is there less panting?
• Is your dog stronger or more active?
• Has your dog developed vomiting, diarrhea, weakness, or poor appetite?

Some veterinarians use the ACTH stimulation test for routine monitoring. Others may use a cortisol measurement taken before the daily medication. The monitoring plan can vary depending on the dog, the medication, and the veterinarian's protocol.

Timing matters, so follow your clinic's instructions carefully about when to give medication, whether to feed your dog, and when to arrive for testing.

Getting Cushing's Under Control Takes Time

Cushing's is not usually a condition where we start one dose of medication and never need to change it.

Dogs respond differently. The starting dose may be too strong, not strong enough, or appropriate initially but need adjustment later.

A common monitoring schedule includes a recheck shortly after beginning medication, another recheck approximately one month later, and continued testing every few months once the dog is stable. Dogs that are not yet controlled may need more frequent visits.

Every time the dose changes, additional monitoring may be needed.

This process can be time-consuming. It may take several weeks or months to find the dose that controls the symptoms without lowering cortisol too far.

Let's Talk Honestly About Cost

Cushing's can be expensive to diagnose and manage.

I believe owners deserve to know that before testing begins—not after several bills have already accumulated.

The initial investigation may include:

• A veterinary examination
• Routine bloodwork
• Urine testing
• A urine culture to look for a hidden infection
• The all-day suppression test
• Additional hormone testing
• An abdominal ultrasound
• Referral to an internal-medicine specialist in complicated cases

After diagnosis, ongoing expenses may include:

• Daily medication
• Recheck examinations
• Repeat bloodwork
• Cortisol monitoring
• ACTH stimulation testing
• Treatment for urinary or skin infections
• Additional testing when the dog's symptoms change

Medication cost often depends on the dog's size and required dose. A larger dog may need substantially more medication than a small dog.

Individual hormone tests may cost several hundred dollars, depending on the clinic and region. When the examination, preliminary laboratory work, diagnostic testing, medication, and early rechecks are combined, the first year of care can reach several thousand dollars. Specialty imaging or surgery for an adrenal growth can cost considerably more.

These are broad estimates, not guaranteed prices. Ask your veterinary clinic for a written estimate that separates:

• The cost of reaching the diagnosis
• The monthly medication cost
• The expected early monitoring schedule
• The expected cost once your dog is stable
• Possible additional costs if the first test is inconclusive

This discussion is not meant to frighten or discourage anyone from treating their dog. It allows families to understand the commitment, plan ahead, and make informed decisions.

Is Treatment Worth the Expense and Effort?

For many dogs, yes.

Successful treatment can reduce the constant thirst, frequent urination, intense hunger, panting, muscle weakness, and recurring infections. Dogs may sleep through the night again, have fewer accidents, regain strength, and become more comfortable and active.

Drinking, urination, appetite, and panting may begin improving during the first several weeks. Muscle strength, skin changes, and hair growth usually take longer and may require several months.

The goal is not simply to improve a laboratory result.

The goal is to help your dog feel better and enjoy a better quality of life.

When Should I Call the Veterinarian?

Contact your veterinarian promptly if a dog taking Cushing's medication develops:

• Poor appetite or refuses food
• Vomiting
• Diarrhea
• Unusual tiredness
• Weakness
• Trembling
• Collapse

These signs could mean the medication has lowered cortisol too far or that another illness is present.

Do not adjust the dose yourself. Contact the prescribing veterinarian for instructions.

Should I Limit My Dog's Water?

No.

Do not restrict access to water, even if your dog is drinking and urinating excessively. Your dog is drinking because the body believes it needs that water. Restricting it could cause dehydration or other serious problems.

Keep fresh water available and schedule an examination to determine why the increased thirst is happening.

The Bottom Line

Cushing's means your dog's body is acting as though it is constantly stuck in fight-or-flight mode.

Too much cortisol, over too much time, begins affecting thirst, urination, appetite, breathing, muscles, skin, hair, and the immune system.

Diagnosing the condition may require an all-day test, repeat testing, imaging, and several appointments. Once treatment begins, finding the right dose can take time, and continued monitoring is essential.

It can be a significant financial commitment. But when treatment is successful, the improvement in comfort and quality of life can be very meaningful for both the dog and the family.