Hyperadrenocorticism [Cushing's Disease]
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Hyperadrenocorticism, commonly called Cushing’s disease, occurs when the body is exposed to excessive cortisol for a prolonged period. Most naturally occurring cases are caused by a small tumour in the pituitary gland that produces too much ACTH, which in turn stimulates both adrenal glands. A smaller proportion arise from a cortisol-producing tumour in one adrenal gland. Similar clinical signs can also be caused by long-term or excessive treatment with corticosteroid medication, known as iatrogenic Cushing’s syndrome.
The disease mainly affects middle-aged and older dogs. Common signs include increased thirst and urination, increased appetite, panting and a gradual change in body shape. Muscle loss can make the abdomen appear pendulous or “pot-bellied,” while the skin may become thin and the coat sparse, particularly over the trunk. Dogs can bruise easily, develop recurrent skin or urinary infections and become less tolerant of exercise. Some signs are subtle at first and may be attributed to ageing.
Cortisol influences many body systems, so untreated disease can contribute to high blood pressure, blood clots, diabetes mellitus, gallbladder disease and other complications. No single outward feature separates cortisol excess from the many age-related disorders that produce similar thirst, appetite, skin or body-shape changes.
Not every dog with elevated liver enzymes, increased thirst or a pot-bellied appearance has Cushing’s disease. The pattern and persistence of compatible changes matter more than any isolated sign, because several common illnesses can mimic parts of the syndrome.
Early detection is instead based on recognising a consistent group of signs in a middle-aged or older dog. Increased thirst and urination, persistent hunger, panting, muscle weakness, recurrent infections, thin skin and symmetrical hair loss are particularly useful clues. A sustained combination of increased thirst, urination and appetite with physical changes is more characteristic than any single isolated feature.
Screening & Early Detection
Routine endocrine testing of a completely healthy dog is generally not recommended because Cushing’s tests can produce misleading results when the clinical suspicion is low.
Routine blood work may show changes such as increased alkaline phosphatase, cholesterol or glucose, and urinalysis may reveal dilute urine or infection. These findings support further investigation but are not diagnostic. A urine cortisol-to-creatinine ratio can be useful as a sensitive rule-out test in some cases, while endocrine testing is used to confirm inappropriate cortisol regulation.
The choice of test depends on the dog’s signs, medication history and other illnesses. Corticosteroid drugs, including some ear, skin and eye preparations, can affect testing and must be discussed with the veterinarian. Once hyperadrenocorticism is confirmed, abdominal ultrasound or additional testing may help determine whether the source is pituitary or adrenal.
Do not wait for severe weakness or diabetes to develop.
Veterinarians combine clinical signs with blood and urine testing and use endocrine tests such as a low-dose dexamethasone suppression test or ACTH stimulation test in appropriate circumstances. Ultrasound and additional hormone testing may then help distinguish pituitary-dependent from adrenal-dependent disease. Once accurately diagnosed, many dogs can be managed successfully for years, although treatment requires ongoing monitoring because both excessive cortisol and excessive suppression of cortisol can be harmful.
Treatment & Management
Treatment depends on whether the excess cortisol is pituitary-dependent, adrenal-dependent or caused by medication. Most pituitary-dependent cases are managed medically with a drug that reduces cortisol production by the adrenal glands. Trilostane is commonly used and can be very effective, but the dose must be monitored because excessive suppression can cause dangerous cortisol deficiency. Follow-up blood tests and assessment of clinical signs are therefore essential.
An adrenal tumour may also be managed medically, but surgical removal can be considered when imaging suggests the tumour is operable and the dog is an appropriate anaesthetic candidate. These procedures are specialised because adrenal tumours can be closely associated with major blood vessels. Large pituitary tumours causing neurological signs may require referral for advanced treatment such as radiation therapy.
Iatrogenic Cushing’s syndrome is managed by carefully reducing the corticosteroid medication responsible. Steroids must not be stopped suddenly after prolonged use because the dog’s own adrenal function may be suppressed. Withdrawal is planned gradually under veterinary supervision while the original disease requiring steroids is also addressed.
Successful treatment usually reduces excessive drinking, urination and appetite before coat and muscle changes fully improve. Report vomiting, diarrhoea, marked weakness, collapse or sudden loss of appetite promptly because these can signal over-treatment or another complication. Lifelong monitoring is common, with medication adjusted as the dog’s response changes.
Breeds or species affected
Boston terrier
Open dog breed description, care requirements and conditions
Boxer
Open dog breed description, care requirements and conditions
Dachshund
Open dog breed description, care requirements and conditions
Dandie Dinmont terrier
Open dog breed description, care requirements and conditions
German shepherd
Open dog breed description, care requirements and conditions
Miniature Poodle
Open dog breed description, care requirements and conditions
Poodle (standard)
Open dog breed description, care requirements and conditions
Toy Poodle
Open dog breed description, care requirements and conditions
Rottweiler
Open dog breed description, care requirements and conditions
Yorkshire terrier
Open dog breed description, care requirements and conditions