Cushing’s Syndrome in Dogs: Signs, Diagnosis, Treatment and Monitoring
A detailed guide to canine Cushing’s syndrome covering classic signs, diagnostic testing, pituitary and adrenal causes, trilostane monitoring and emergencies.
What Cushing’s syndrome means
Cushing’s syndrome, also called hypercortisolism or hyperadrenocorticism, describes clinical illness caused by prolonged excessive glucocorticoid exposure. Most naturally occurring cases are pituitary-dependent, in which a pituitary tumour drives both adrenal glands to produce cortisol. A smaller group has an adrenal tumour producing cortisol independently. Long-term administration of steroid medicines can cause iatrogenic disease.
The pattern of signs
Water, urine and appetite
- Drinking and urinating more
- Indoor accidents or needing night toilet breaks
- Increased appetite or food-seeking
- Recurrent urinary infection, sometimes without obvious discomfort
Body and breathing
- Panting at rest
- Muscle wasting and weakness
- Pendulous or “pot-bellied” abdomen
- Reduced exercise tolerance
Skin and coat
- Thin skin and easy bruising
- Symmetrical hair loss or slow regrowth
- Recurrent skin infection
- Blackheads, mineralised skin lesions or poor wound healing
The disease usually develops gradually, so families may attribute changes to ageing or Indian summer heat. A measured water-intake record, serial body photographs and a timeline of skin and appetite changes are more useful than relying on memory.
When testing is appropriate—and when it is not
Testing is most valuable when multiple compatible clinical signs are present and the minimum database—complete blood count, serum biochemistry and urinalysis—supports suspicion or excludes alternatives. Blood pressure, urine culture and urine protein measurement may be recommended.
Stress, uncontrolled diabetes and other illness can create false-positive endocrine results. Screening an otherwise well dog solely because ALP is high is a common path to overdiagnosis. The clinician should first review steroid exposure, liver disease, diabetes, infection and other causes.
Diagnostic tests and what they answer
| Test | Best use | Key limitation |
|---|---|---|
| Low-dose dexamethasone suppression test | Common first-line diagnostic test; some patterns can suggest pituitary dependence | False positives occur with stress and non-adrenal illness. |
| ACTH stimulation test | Useful in selected cases and for some treatment-monitoring strategies | Lower sensitivity for naturally occurring disease than LDDST. |
| Urine cortisol-to-creatinine ratio | Sensitive rule-out test when collected in a low-stress home setting | Poor specificity; a positive result does not confirm Cushing’s. |
| Endogenous ACTH | Helps distinguish pituitary-dependent from adrenal-dependent disease after diagnosis | Sample handling is demanding and it is not a screening test. |
| Abdominal ultrasound | Assesses adrenal glands and other abdominal organs | Adrenal appearance alone does not diagnose functional disease. |
No test is perfect. Results must be interpreted with clinical probability. Repeating or using a different test may be safer than labelling an inconsistent result as Cushing’s syndrome.
Pituitary, adrenal and iatrogenic disease
Pituitary-dependent disease is commonly treated medically. Adrenal tumours may be candidates for surgery after staging and assessment by an experienced team, though medical management may be chosen. Iatrogenic disease requires a carefully planned steroid reduction when possible; abrupt withdrawal after chronic exposure can cause dangerous adrenal insufficiency.
Treatment and monitoring
Trilostane is commonly used to reduce cortisol synthesis. It controls the hormonal excess but does not remove a pituitary tumour. The dose and monitoring plan are individual. Clinical signs—water intake, appetite, panting, energy, vomiting and stool—are central to judging safety and benefit.
Monitoring approaches continue to evolve. Depending on the clinic and dog, assessment may include history, examination, electrolytes and cortisol-based testing. The family must know what time the medicine was given and whether it was given with food, because timing affects interpretation.
Contact the prescribing veterinarian urgently for
- Refusal to eat, vomiting or diarrhoea
- Marked weakness, shaking, collapse or severe lethargy
- A sudden major reduction in drinking combined with illness
- Abnormal sodium or potassium results
- Any concern that too much medicine was given
These signs can indicate excessive cortisol suppression, adrenal crisis or another acute illness. Follow the written emergency plan; do not give the next dose until the treating team advises what to do.
Concurrent problems that need attention
Dogs with Cushing’s syndrome may have hypertension, proteinuria, urinary infection, gallbladder disease, diabetes, pancreatitis, blood-clot risk, skin infection or osteoarthritis. Treating cortisol excess does not automatically resolve every complication. Persistent weakness or panting after improved hormone control deserves reassessment.
A home-monitoring dashboard
- Measure water intake for several representative days before and after treatment changes.
- Record appetite, panting, urination, accidents and energy weekly.
- Weigh the dog and photograph top and side views monthly.
- Write medicine and meal times before every monitoring appointment.
- Report vomiting, diarrhoea, poor appetite or weakness immediately.
- Keep a complete list of steroid-containing products and supplements.
Making treatment decisions without chasing one cortisol number
The goal of therapy is to improve the dog’s clinical signs safely, not to produce the lowest possible cortisol result. A dog that is eating, active and drinking less but has a laboratory value outside a preferred target may need a different decision from a dog with vomiting, weakness or electrolyte change. Results must be interpreted with medicine timing, meal timing, assay method and the dog’s behaviour on the day.
Families should also understand what treatment cannot guarantee. Medical control may improve thirst, appetite, panting, skin and muscle function, but it does not remove every pituitary tumour, reverse advanced calcinosis cutis immediately or cure unrelated arthritis and airway disease. Improvement is often gradual and uneven.
| Observation | Possible meaning | Action |
|---|---|---|
| Water intake gradually falls and dog remains well | Possible therapeutic response | Record trend and attend scheduled monitoring |
| Vomiting, diarrhoea or refusal to eat | Possible excessive adrenal suppression or other acute illness | Follow emergency instructions and contact veterinarian before the next dose |
| Persistent panting despite improved thirst | Heat, obesity, airway disease, pain or incomplete control | Reassess rather than increasing medicine automatically |
| New weakness or collapse | Potential adrenal crisis, electrolyte problem or unrelated emergency | Emergency assessment |
Monitoring is most reliable when the same family member gives the medicine, records the meal and brings a concise symptom diary. Random dose changes based on isolated water intake or one laboratory result increase risk.
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