Cushing's Disease in Senior Dogs: Signs, Tests, Treatment

A senior dog who drinks more, pees more, eats like a puppy and develops a round belly is easy to wave off as “just getting old.” Sometimes that cluster of changes is something specific and treatable: Cushing’s disease.

This guide covers what Cushing’s disease is, the three different causes, the signs that get mistaken for aging, how veterinarians confirm it, what treatment and monitoring look like, and when a symptom is urgent. It is general information, not veterinary advice. Cushing’s cannot be diagnosed from symptoms alone, and nothing here replaces an exam and testing by your own vet. For the wider picture of older-dog care, see the senior dog health guide.

Key takeaways

• Cushing’s disease (hyperadrenocorticism) means the body makes too much cortisol for too long. The MSD Veterinary Manual calls it a common hormone disorder of adult and aged dogs.
• Most cases (about 85-90%) come from a small tumor on the pituitary gland; most of the rest come from a tumor on an adrenal gland. Long-term steroid medication can also cause Cushing’s-like signs.
• The classic signs are more drinking, more urinating, a bigger appetite, a pot belly, panting, thin skin and hair loss. Each one is easy to blame on age, which is why the condition is often noticed late.
• Diagnosis takes a vet visit and several tests, not one quick check. Treatment, when needed, is usually a daily medication with regular monitoring, and many dogs do well for years.
• Never start, stop or adjust any Cushing’s medication on your own. Both too little and too much can cause problems, and only your vet can judge the balance.

What is Cushing’s disease in dogs?

Cushing’s disease is the common name for hyperadrenocorticism: the adrenal glands, two small glands next to the kidneys, produce too much of the stress hormone cortisol. Cortisol is essential in normal amounts. In excess over months or years it thins the skin, weakens muscle, raises blood sugar and blood pressure in some dogs, and changes thirst, appetite and urination.

The MSD Veterinary Manual describes the condition as affecting middle-aged to older dogs, typically around 7-12 years old, and it can occur in any breed or size (MSD Veterinary Manual, Cushing disease in animals). The same page lists Miniature Poodles, Dachshunds, Boxers, Boston Terriers, Yorkshire Terriers and Staffordshire terriers among breeds more often affected. That age range overlaps with when many dogs count as seniors; see what age is a dog considered senior for how that threshold varies by size.

What causes Cushing’s disease?

There are three routes to too much cortisol, and which one a dog has changes the treatment plan.

Pituitary-dependent (the most common). A small tumor on the pituitary gland at the base of the brain releases too much of a hormone (ACTH) that tells the adrenal glands to keep making cortisol. VCA Hospitals puts this at 85-90% of cases, and notes that a minority of these pituitary tumors are large enough to cause neurological signs (VCA Hospitals).

Adrenal-dependent. A tumor on one adrenal gland makes cortisol on its own. The MSD Veterinary Manual gives about 10-15% of cases and says these tumors can be benign or malignant, and that this form is more common in larger dogs (MSD Veterinary Manual, Cushing syndrome). Benign tumors can sometimes be cured by surgery; VCA describes the outlook for malignant ones as much less favorable.

Iatrogenic (caused by medication). Long-term steroid medication, whether pills or injections, can produce the same picture. The MSD Veterinary Manual’s owner pages list this alongside the tumor causes. VCA’s advice for this form is to taper the steroid gradually under veterinary direction, and it adds that the condition the steroid was treating may return. If your dog is on a steroid, do not stop it suddenly; ask your vet about the plan.

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

The signs build slowly, usually over months, and tend to arrive together. According to VCA Hospitals and the MSD Veterinary Manual, the common ones are:

• Drinking and urinating much more. Accidents in the house or waking you at night to go out.
• Increased appetite. Begging, stealing food, acting ravenous.
• A pot-bellied, pendulous abdomen.
• Panting, including at rest or at night.
• Thin skin and hair loss. The coat may thin, especially on the flanks, and skin can look dull or darker.
• Muscle weakness or wasting, such as trouble jumping or climbing.
• Lethargy and a poor hair coat.
• Recurring infections, especially skin or bladder infections, and slow wound healing.

The MSD Veterinary Manual also notes that many dogs with Cushing’s have high blood pressure, which is one reason a vet will check it.

Why it gets mistaken for normal aging

Almost every item above has an easy “old age” explanation. Panting is blamed on the heat, a bigger belly on weight gain, thinner fur on aging, weaker back legs on arthritis, more peeing on a weak bladder. Taken one by one, each excuse sounds reasonable. Taken together, especially with increased thirst and appetite, they point to something a vet should look at.

The senior health guide makes the same point: old age is not a disease, and any noticeable change in an older dog is a reason for a vet conversation, not a shrug. Several other conditions also cause heavy drinking and urinating, including kidney disease and diabetes, so guessing at home is not reliable.

How do vets diagnose Cushing’s disease?

No single test is perfect, so vets combine the story, the exam and several tests. The sequence below follows the descriptions from VCA Hospitals and the MSD Veterinary Manual; your vet may choose differently.

1. History and physical exam. This is the starting point. Testing for Cushing’s is generally done when the signs fit, because the tests can be misleading in dogs that are ill from something else.
2. Routine bloodwork and urine tests. A complete blood count, chemistry panel and urinalysis do not diagnose Cushing’s, but they often show clues. A raised liver enzyme called ALP is the most common one, and urine that is very dilute or contains protein is also common.
3. Screening tests for cortisol. The two names owners hear most are the ACTH stimulation test and the low-dose dexamethasone suppression test (LDDS). In plain words, both involve a blood sample, a small injection, and further blood samples a few hours later to see how the adrenal glands respond. The MSD Veterinary Manual calls the LDDS the screening test of choice and says the ACTH stimulation test is less sensitive and cannot tell the pituitary form from the adrenal form. A urine cortisol:creatinine ratio is another test VCA lists; it uses a urine sample, and it is more useful for ruling out the disease than for confirming it.
4. Finding out which type it is. Further tests can separate the pituitary form from the adrenal form. An abdominal ultrasound looks at the adrenal glands: two evenly enlarged glands suggest the pituitary form, while one large gland suggests an adrenal tumor. Other blood tests, such as measuring ACTH or a high-dose dexamethasone test, may also help. Advanced imaging such as CT or MRI is sometimes used before surgery or radiation.

Because the testing is interpreted alongside the whole picture, a vet may sometimes repeat a test or hold off on treatment. That is normal and not a sign of indecision.

How is Cushing’s disease treated?

Not every dog with a positive test is treated right away. Treatment is generally aimed at dogs showing signs that affect their comfort or health, and the plan depends on the type. The notes below are an overview only. Doses and schedules are set by your vet, based on your dog.

Pituitary form: daily medication. Trilostane is the most commonly used drug according to VCA, and the MSD Veterinary Manual calls it the treatment of choice for most dogs, with exceptions such as dogs with a skin condition called calcinosis cutis or atypical disease. Mitotane is an older alternative with more side effects, which VCA says is used less often. Surgery on the pituitary or radiation therapy are options at some referral centers, though they are not available everywhere.

Adrenal form: surgery where possible. Removing the affected adrenal gland is described by the MSD Veterinary Manual as the treatment of choice, but it is major abdominal surgery with real risk, so vets weigh the dog’s age and health carefully. VCA says complete removal of a benign tumor gives a good chance of recovery. When surgery is not an option, medication can be used, though the response may be weaker.

Medication-caused form. The usual approach is a supervised, gradual reduction of the steroid, as above.

Why monitoring matters

Trilostane does not cure Cushing’s. It reduces how much cortisol the adrenal glands make, and it has to be given consistently, often for the dog’s life. VCA says follow-up blood tests and the dog’s clinical signs are used to check the dose, because both too little and too much cause complications. The MSD Veterinary Manual reports that most clinicians use an ACTH stimulation test to check that cortisol stays in a normal range, and it lists reversible mineralocorticoid insufficiency as an adverse effect, with permanent adrenal damage reported only rarely.

In practice this means rechecks, often more frequent early on and then spaced out, and a dog who sometimes needs the plan adjusted. Skipping a recheck is not a harmless shortcut.

What does day-to-day life with a Cushing’s dog look like?

For a dog on treatment, daily life is mostly routine with a few extra jobs. These are common-sense suggestions to discuss with your vet, not medical instructions.

• Give medication exactly as directed, at consistent times. Ask what to do about a missed dose before it happens.
• Keep fresh water always available. Thirst is a symptom; never restrict water to cut down on accidents. Offer more frequent outdoor breaks and put washable pads or bedding down instead.
• Watch the scale and the waistline. A dog with a big appetite can gain weight. Keep portions measured and ask your vet before changing food. If your dog is also on a thyroid-related diet, the hypothyroidism food guide covers how vets think about diet for hormone conditions.
• Keep a short log. Note drinking (a rough number of bowl refills), appetite, energy, panting and accidents. Improvement in thirst and appetite is typically what vets look for in the first weeks, and a log makes the pattern visible.
• Protect thin skin. Be gentle when grooming and handling, and have any wound, bladder or skin infection checked promptly, since Cushing’s makes both more likely.
• Keep up with the senior checkups. Cushing’s often comes with other conditions, such as high blood pressure and urinary tract infections, so regular exams and bloodwork matter more, not less.

What is the outlook for a dog with Cushing’s?

Prognosis varies a great deal. The MSD Veterinary Manual describes the outlook for the pituitary form as generally good, and says median survival is about 2 years whether or not medical treatment is given, with early disease and no other illnesses allowing much longer survival on medication. That figure reflects that many affected dogs are already old, and that some die of unrelated conditions. VCA similarly says medication cannot cure the disease but that control is possible for many years when the pituitary tumor is small.

The picture is less favorable when a pituitary tumor is large enough to cause neurological signs, and for malignant adrenal tumors, which VCA describes as guarded to poor. A benign adrenal tumor removed by surgery can be curable. Because every case differs, ask your vet what is realistic for your dog rather than relying on averages.

Questions to ask your vet

Bringing a list to the appointment makes the visit more productive.

• Which signs fit Cushing’s for my dog, and which could be something else?
• Which tests do you recommend, and what could make the results unreliable?
• Is this the pituitary or adrenal form, and does that change the plan?
• Does my dog need treatment now, or is monitoring reasonable?
• If medication is recommended, what are the side effects to watch for, and which ones mean I should call right away?
• How often will rechecks be needed, and what will they cost over the first year?
• Are there other conditions, such as high blood pressure or urinary infections, that should be checked for?
• What would an emergency look like, and who do I call after hours?

When is it urgent?

Cushing’s itself is usually a slow condition, but some situations are not routine. Call your vet or an emergency clinic promptly for:

• A dog on Cushing’s medication who becomes weak, collapses, vomits, has diarrhea or stops eating. Over-suppressing cortisol can cause adrenal insufficiency, and the MSD Veterinary Manual lists loss of appetite, vomiting and diarrhea among the warning signs of that problem with mitotane. Do not wait for the next scheduled recheck.
• Sudden changes in the nervous system, such as circling, seizures, apparent blindness or marked confusion, which can happen when a pituitary tumor is large.
• Straining to urinate, blood in the urine or signs of a bladder infection. These can be more serious in a dog with Cushing’s.
• Sudden severe weakness, labored breathing or a swollen, painful belly. These are emergencies for any dog regardless of the cause.

When in doubt, phone the clinic and describe what you are seeing; they can triage by phone.

Frequently asked questions

Is Cushing’s disease in dogs painful?

Cushing’s itself is not usually described as painful, but its effects, such as muscle weakness, skin infections, bladder infections and urine accidents, can make a dog uncomfortable. Most owners report the daily thirst, appetite and panting as the hardest part. Your vet can address each of these.

Can Cushing’s disease be cured?

Sometimes. A benign adrenal tumor that is fully removed by surgery can be curable, according to VCA. The more common pituitary form is usually controlled with lifelong medication rather than cured.

How long can a dog live with Cushing’s disease?

It varies. The MSD Veterinary Manual gives a median survival of about 2 years for the pituitary form, with dogs diagnosed early and free of other illness living considerably longer on treatment. Your dog’s age, other health problems and tumor type all matter.

Does my dog have to be treated?

Not always. Vets usually recommend treatment when a dog has signs that affect health or comfort. Ask your vet whether monitoring or treatment makes sense for your dog and why.

Are steroid medications a risk for Cushing’s disease?

Long-term steroid pills or injections can cause a Cushing’s-like condition, per the MSD Veterinary Manual and VCA Hospitals. Never stop a steroid abruptly; ask your vet about the safest way to adjust it.

Is there anything I can do at home to treat Cushing’s?

No home remedy replaces testing and veterinary treatment. What you can do is give prescribed medication correctly, keep water available, maintain a healthy weight, log changes and attend rechecks.

The bottom line

Increased thirst, urination and appetite plus a pot belly and thinning coat in an older dog should not be written off as aging. They are a reason for a vet visit, because Cushing’s disease is common in older dogs, can be diagnosed, and is often manageable with regular monitoring. The most useful thing an owner can do is notice the pattern, record it, and bring it to the appointment. For the broader checklist of senior health changes worth watching, return to the senior dog health guide.

Note on review: This article is general information compiled from veterinary sources (VCA Hospitals and the MSD Veterinary Manual). It is not veterinary advice and has not been independently reviewed by a veterinarian. Always rely on your own vet for diagnosis and treatment decisions.