Cushing's syndrome in dogs: signs, tests and treatment

Cushing syndrome is the group of changes caused when a dog is exposed to too much cortisol or a similar steroid hormone over time.

Cortisol is essential in normal amounts, but persistent excess affects many tissues at once. That is why the condition can change thirst, appetite, breathing, muscles, skin and the shape of the abdomen. [1]

Cushing syndrome is the broad name for the effects of excessive steroid hormones, while Cushing disease specifically means the pituitary-dependent form.

Every dog with pituitary-dependent Cushing disease has Cushing syndrome, but the syndrome can instead come from an adrenal tumour or prolonged exposure to steroid medicines. The distinction matters because the treatment options are not identical. [2]

Too much cortisol affects many parts of a dog's body because the hormone normally helps regulate metabolism, stress responses, inflammation and fluid balance.

When exposure remains excessive, those useful effects become harmful. Muscles and skin can weaken, the liver and blood chemistry may change, resistance to infection can fall, and thirst and urine production often rise. [3]

Pituitary-dependent Cushing disease begins with a usually small pituitary tumour that sends too much stimulating hormone to the adrenal glands, causing them to make excess cortisol.

The pituitary gland sits at the base of the brain and normally controls adrenal activity. Most pituitary tumours remain small, but a larger one can sometimes cause neurological signs as well as hormonal disease. [3]

Adrenal-dependent Cushing syndrome happens when a tumour in an adrenal gland produces cortisol without normal control from the pituitary gland.

An adrenal tumour may be benign or malignant. Identifying this form matters because surgery to remove the affected adrenal gland may be an option, while imaging also helps assess spread and surgical risk. [4]

Yes. Prolonged or excessive exposure to steroid medication can produce iatrogenic Cushing syndrome, which means the condition was caused by medical treatment rather than a naturally overactive gland.

Steroid exposure can come from more than tablets, including some injections, skin, ear or eye preparations. The medication history is therefore an important part of investigating compatible signs. [2]

Cushing syndrome is diagnosed most often in middle-aged and older dogs, although any breed or size can be affected.

Pituitary-dependent disease is reported particularly often in smaller breeds, while adrenal-dependent disease is also seen in larger dogs. Age, breed and the dog's overall pattern of signs all shape clinical suspicion rather than proving the diagnosis. [4]

Dogs with Cushing syndrome often drink and urinate more because prolonged cortisol excess interferes with the body's ability to conserve water.

Owners may notice larger water-bowl visits, fuller urine patches, night-time trips, accidents or worsened incontinence. These changes also occur with other illnesses, so they support investigation but do not identify Cushing syndrome by themselves. [1]

Yes. Cushing syndrome commonly increases appetite, so a dog may seem persistently hungry or become more intent on finding food.

That change can be striking even when the dog is losing muscle or developing a rounded abdomen. Increased appetite has many possible causes, so vets interpret it alongside thirst, urination, skin changes and other findings. [3]

Cushing syndrome can cause noticeably more panting, including at times when a dog is not exercising or obviously hot.

Panting may occur alongside heat intolerance, muscle weakness and abdominal enlargement. Because breathing changes can also signal pain, heart or lung disease, a new or marked change deserves veterinary assessment rather than being assumed to be hormonal. [2]

Cushing syndrome can create a pot-bellied outline through a combination of weakened abdominal muscles, changes within the liver and redistribution of body fat.

The abdomen may look rounded even while the limbs and back lose muscle. A swollen abdomen has other possible causes, including fluid or an enlarged organ, so appearance alone cannot confirm Cushing syndrome. [4]

Yes. Persistent cortisol excess can waste muscle, leaving a dog weaker, less energetic or less able to manage stairs, jumping and longer walks.

Muscle loss may be most visible over the back and limbs while the abdomen becomes more prominent. Weakness can have many causes, so its speed, severity and accompanying signs help guide the work-up. [4]

Cushing syndrome can cause thinning hair, symmetrical bald areas, slow regrowth, darker or thinner skin, blackheads, bruising and recurrent skin infections.

The pattern often affects the body more than the head and feet and may not be very itchy unless infection is present. Several other hormonal and skin disorders look similar, so examination and testing are needed to separate them. [2]

Cushing syndrome can weaken normal tissue and immune defences, contributing to recurrent skin or urinary infections and wounds that heal slowly.

A urinary infection may sometimes be present without the usual obvious inflammatory clues in the urine. Repeated infections, fragile skin or delayed healing therefore add useful context when a vet is considering the wider pattern. [2]

Cushing syndrome can be associated with high blood pressure, urinary infection, diabetes, blood clots and gallbladder disease, although not every dog develops these problems.

Some complications are more immediately serious than the gradual hormonal signs. A dog's assessment may therefore include blood pressure, urine and metabolic checks as well as tests aimed directly at cortisol. [5]

Yes. If a pituitary tumour becomes large, it can press on nearby brain structures and cause behaviour change, altered awareness, vision problems, poor appetite, circling or seizures.

These signs come from the mass itself rather than from cortisol excess alone. New neurological changes in a dog with known or suspected pituitary disease warrant urgent veterinary assessment and may change the imaging and treatment plan. [2]

Testing for Cushing syndrome is most useful when a dog's history, examination and routine results create a recognisable pattern of compatible signs.

A single vague symptom or an isolated blood-test change gives a weaker basis for endocrine testing. The more consistent findings that occur together, the more meaningful a properly chosen result becomes. [5]

No single test identifies Cushing syndrome perfectly in every dog, so diagnosis combines the clinical picture with routine laboratory findings and targeted hormone tests.

Stress and unrelated illness can produce misleading positive results, while some affected dogs have inconclusive results. Test choice and interpretation therefore depend heavily on how well the dog's signs fit the condition. [1]

A Cushing syndrome work-up usually starts with a full blood count, blood chemistry and urinalysis rather than a hormone test in isolation.

Blood pressure, a urine culture and a urine protein check may also be relevant. These tests look for the wider effects of cortisol, possible complications and alternative explanations for the dog's signs. [1]

No. A raised alkaline phosphatase, usually shortened to ALP, is common in dogs with Cushing syndrome but cannot diagnose the condition by itself.

ALP can rise for several reasons, including other liver or hormonal effects and some medicines. Its value comes from fitting it into the dog's symptoms, examination, other laboratory results and any appropriate endocrine testing. [4]

A urine cortisol-to-creatinine ratio is mainly useful for making Cushing syndrome unlikely when the result is low; a high result does not confirm the disease.

Many stresses and illnesses can raise the ratio, which creates false positives. A positive result therefore needs interpretation within the clinical picture and usually further testing before Cushing syndrome is diagnosed. [1]

The low-dose dexamethasone suppression test checks whether a dog's cortisol production responds normally to a steroid feedback signal and is a preferred first-line test when suspicion is strong.

Several blood samples are compared over the test period. The response pattern may support Cushing syndrome and sometimes point towards the pituitary form, but stress or another illness can still cause a misleading result. [1]

An ACTH stimulation test measures how strongly a dog's adrenal glands produce cortisol after receiving a synthetic version of their normal stimulating hormone.

It is particularly useful when iatrogenic Cushing syndrome is suspected and is also used in treatment monitoring. It can miss naturally occurring disease, especially some adrenal tumours, so a normal result is not universally conclusive. [1]

No. One resting blood cortisol result cannot diagnose Cushing syndrome because normal cortisol output naturally rises and falls through the day.

Stress and unrelated illness can also raise a single measurement, while an affected dog's value may sometimes sit within the usual range. Dynamic hormone testing asks a more informative question about how the control system responds. [5]

Yes. Acute illness and stress can distort Cushing syndrome tests and create false-positive results, so the immediate illness often needs assessment before endocrine conclusions are drawn.

Loss of appetite, vomiting and diarrhoea are not typical effects of cortisol excess itself. In a sick dog they may reflect another illness, a complication or dangerously low cortisol during treatment, each of which needs urgent veterinary attention. [1]

Distinguishing pituitary-dependent from adrenal-dependent Cushing syndrome helps explain where the excess hormone signal begins and which treatment options are realistic.

The distinction can affect surgery decisions, imaging, prognosis and specialist referral. It may come from the hormone-test pattern, abdominal imaging and an endogenous ACTH measurement rather than from one result alone. [1]

Imaging can examine the adrenal glands and pituitary region, help distinguish the likely source of Cushing syndrome and plan possible surgery or radiotherapy.

Abdominal ultrasound can show adrenal size, shape and a visible mass, while computed tomography or magnetic resonance imaging provides more detail where surgical planning or a larger pituitary tumour is a concern. [2]

An endogenous ACTH test helps locate the source after Cushing syndrome has been established by measuring the dog's own pituitary stimulating hormone.

A higher concentration supports a pituitary source, while a very low concentration supports an adrenal tumour that has switched off the normal pituitary signal. Sample handling is demanding, so the result needs careful laboratory interpretation. [2]

Treatment aims to reduce harmful cortisol exposure, improve the dog's troublesome signs, lower complication risks and preserve a good quality of life.

The route depends on whether the cause is pituitary, adrenal or medication-related and on the dog's overall health. Medical control is common, while selected tumours may be addressed with specialist surgery or radiotherapy. [2]

Trilostane controls Cushing syndrome by blocking part of the adrenal glands' cortisol-making pathway, reducing excess hormone production without removing the underlying tumour.

It is widely used for pituitary-dependent disease and can also control adrenal-dependent disease when surgery is not chosen. The effect varies between dogs, so clinical response and cortisol safety checks remain central to care. [2]

Yes. Removing the affected adrenal gland is the preferred treatment for a suitable dog with adrenal-dependent Cushing syndrome when the tumour is considered operable.

This is specialist surgery with meaningful anaesthetic, bleeding and hormone-related risks. Detailed imaging, assessment for invasion or spread, the dog's other illnesses and the experience of the surgical team all influence whether it is appropriate. [1]

Yes. Specialist pituitary surgery or radiotherapy can treat the tumour itself in selected dogs, while medical treatment mainly controls its hormonal effects.

Availability, tumour size, neurological signs, general health and the centre's expertise shape the choice. Brain imaging is usually needed when direct tumour treatment is being considered or a larger pituitary mass is suspected. [2]

Medication-caused Cushing syndrome is managed by the veterinary team reassessing the steroid exposure and, when medically possible, planning a careful gradual reduction.

Abrupt withdrawal can leave the body unable to supply the cortisol it needs and may be dangerous. The original reason for steroid treatment must also remain controlled, so the plan is individual rather than a simple stop. [3]

Regular monitoring checks whether Cushing syndrome signs are improving while ensuring cortisol has not been suppressed too far.

Changes in thirst, urination, appetite, panting, energy and skin health are important alongside veterinary examinations and selected cortisol tests. There is no single monitoring result that replaces the dog's overall clinical response. [1]

Loss of appetite, vomiting, diarrhoea, profound lethargy, weakness or collapse during cortisol-lowering treatment can signal dangerously low cortisol and need immediate emergency veterinary help.

Cushing medicines can occasionally suppress adrenal function too far, and rare permanent adrenal injury has also been reported. A sudden unwell change is therefore different from the gradual improvement expected as excess cortisol comes under control. [3]

Many dogs with well-controlled Cushing syndrome can enjoy a good quality of life, but the outlook varies with the underlying cause, other illnesses and response to treatment.

Thirst and appetite may improve sooner than skin, coat and muscle changes. An adrenal tumour's behaviour or a large pituitary tumour can alter the picture, so published survival figures cannot predict one dog's experience. [3]