FrançaisWhat Cushing’s disease is
Cortisol is a stress hormone made by the adrenal glands under the control of the pituitary gland. In Cushing’s disease, cortisol stays too high. In about 85% of dogs the cause is a pituitary tumour (pituitary-dependent form); in about 15% it is a tumour of an adrenal gland [1]. Long-term steroid medicines can produce the same picture (iatrogenic Cushing’s) [1].
Symptoms of Cushing’s disease in dogs
- Drinking and urinating more (polyuria, polydipsia).
- A big appetite (polyphagia).
- Panting at rest.
- Skin and coat changes: thinning hair, thin skin, a pot-bellied appearance.
These are the classic signs listed by the AAHA guidelines [1]. Cushing’s disease does not cause loss of appetite, vomiting or diarrhoea: if they are present, another illness should be looked for [1].
What the blood work and urine show
| Finding | Why it happens | Read more |
|---|---|---|
| High ALP | Cortisol induces a form of ALP found only in dogs [2]. | High ALP in dogs |
| High cholesterol (and triglycerides) | Cortisol changes how fats are handled [3]. | Cholesterol in dogs |
| Stress leukogram | More neutrophils and monocytes, fewer lymphocytes and eosinophils [4]. | White blood cell count |
| High platelet count | Listed among the classic findings [1]. | CBC for dogs |
| Dilute urine (specific gravity below 1.020) | Cortisol blunts the kidneys’ ability to concentrate urine [1]. | Urinalysis |
| Protein in the urine | Listed among the classic findings [1]. | Protein in urine |
The tests that confirm it
Vets test for Cushing’s only when a dog has at least two compatible signs or lab changes, because every test can give false positives in a dog that is stressed or ill with something else. Testing is usually delayed until 2 to 4 weeks after an acute illness has improved [1, 5].
- Low-dose dexamethasone suppression test (LDDST): the test preferred by the AAHA panel. Cortisol is measured before and 4 and 8 hours after a small dexamethasone injection; a cortisol that is not suppressed at 8 hours supports Cushing’s [1].
- ACTH stimulation test: less affected by stress, but it misses many adrenal tumours; it is the test that identifies steroid-induced Cushing’s [1]. See our ACTH stimulation test article.
- Urine cortisol:creatinine ratio: very sensitive but not specific. A normal result almost always rules Cushing’s out; urine collected at home avoids the stress of the clinic [1].
- Abdominal ultrasound helps tell a pituitary form from an adrenal tumour [1].
Steroid medicines, including ear and eye drops, must usually be stopped 2 to 4 weeks before testing; ask your vet [1].
How to read a cortisol result
Here is an example of the 8-hour line of an LDDST, followed by a converter for reports in nmol/L.
- Abbreviation The 8-hour sample of a low-dose dexamethasone suppression test.
- Result 2.6 µg/dL in this illustrative line: cortisol was not suppressed.
- Unit µg/dL in the United States, nmol/L in Europe: 2.6 µg/dL ≈ 72 nmol/L.
- Laboratory interval The AAHA guidelines give above 1.4 µg/dL at 8 hours as an example cut-off consistent with Cushing’s; each laboratory sets its own [1].
- Flag Above the cut-off: consistent with Cushing’s in a dog with compatible signs. Uncontrolled diabetes or another illness can give a false positive [1].
Unit converter
Equivalent values
- Cortisol, nmol/L–
Conversion only changes the unit. Compare the result with the interval printed by the laboratory that measured it.
Related articles
En français : la maladie de Cushing chez le chien.
Questions to ask your veterinarian
- Which signs and lab results make you suspect Cushing’s disease?
- Which test do you recommend, and why that one?
- Do my dog’s medicines, drops or creams need to be stopped before testing?
- Is the form pituitary or adrenal, and does it change the treatment?
- How will treatment be monitored, and with which tests?
Get your dog’s results explained, line by line.
AI DiagAnimals reads ALP, cholesterol, the white cells, the urine and the cortisol tests together with your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
What are the first signs of Cushing’s disease in dogs?
Usually increased thirst and urination, a larger appetite, panting and a thinning coat or pot belly [1].
Can blood work diagnose Cushing’s disease?
Routine blood work raises the suspicion (high ALP and cholesterol, stress leukogram) but cannot prove it. A specific test such as the LDDST or the ACTH stimulation test is needed [1, 5].
How long can a dog live with Cushing’s disease?
Many dogs live for years with treatment and monitoring. The outlook depends on the form, the dog’s age and other illnesses such as diabetes.
Is the ACTH test accurate for Cushing’s?
It is useful and less affected by stress, but it misses some adrenal tumours. Vets often combine it with other tests and an ultrasound [1].
Are there home remedies for Cushing’s disease in dogs?
No supplement replaces diagnosis and treatment by your vet. Ask before giving any product, as some can interfere with tests or treatment.
Sources
- Bugbee A et al. 2023 AAHA Selected Endocrinopathies of Dogs and Cats Guidelines. J Am Anim Hosp Assoc. 2023;59(3):113-135. doi.org/10.5326/JAAHA-MS-7368
- eClinPath, Cornell University College of Veterinary Medicine. Alkaline phosphatase. eclinpath.com/chemistry/liver/cholestasis/alkaline-phosphatase
- eClinPath, Cornell University College of Veterinary Medicine. Cholesterol. eclinpath.com/chemistry/energy-metabolism/cholesterol
- eClinPath, Cornell University College of Veterinary Medicine. Leukogram patterns. eclinpath.com/hematology/leukogram-changes/leukogram-patterns
- Behrend EN et al. Diagnosis of spontaneous canine hyperadrenocorticism: 2012 ACVIM consensus statement (small animal). J Vet Intern Med. 2013;27(6):1292-1304. doi.org/10.1111/jvim.12192
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.