Low-dose Dexamethasone Suppression Test (LDDST)
The low-dose dexamethasone suppression test (LDDST) measures cortisol, a stress hormone, before and usually at four and eight hours after the vet injects a low dose of dexamethasone. It is commonly used to help diagnose Cushing's disease in dogs and cats.
- Sample
- Serum (0, 4 and 8 hours)
- Quantity
- As advised
- Report
- Confirmed when you book
- Collection
- Free in Bhopal
What this test checks
- Cortisol in a serum sample taken before the dexamethasone injection
- Cortisol in samples usually taken at four and eight hours after the injection
- Whether cortisol falls and stays low, as it should in a healthy animal
- A pattern that may help the vet tell pituitary from adrenal causes in some dogs
Benefits of this test
- Commonly used to help diagnose Cushing's disease in dogs and cats.
- The pattern across the samples can sometimes point to the type of Cushing's disease.
- Gives your vet more information when signs suggest Cushing's disease but other results are unclear.
- All samples are taken during one planned day at the clinic.
When your vet may advise it
- Drinking and passing urine much more than usual, with a bigger appetite.
- A pot belly, thin skin, hair loss on the body or heavy panting.
- Blood tests show changes that may fit Cushing's disease, such as a high liver enzyme called ALP in a dog.
- A cat with diabetes that is hard to control, or very thin and fragile skin.
- A urine cortisol test (UCC ratio) suggests Cushing's disease and your vet wants more evidence.
About this test
Cushing's disease, also called hyperadrenocorticism, happens when the body makes too much cortisol for a long time. Cortisol is a stress hormone made by the adrenal glands, which sit near the kidneys. Dogs with Cushing's disease often drink and pass urine more, eat more and pant a lot. They may develop a pot belly, thin skin or hair loss. It is seen mainly in middle-aged and older dogs and is less common in cats.
The LDDST is commonly used to help diagnose Cushing's disease. Dexamethasone is a steroid that, in a healthy animal, makes the brain switch off its signal to the adrenal glands, so cortisol falls and stays low. The veterinarian takes a blood sample, injects dexamethasone at a low dose the vet chooses and takes more samples, usually at four and eight hours. Cortisol is measured in each serum sample. If cortisol does not fall, or rises again by the last sample, this may indicate Cushing's disease.
In some dogs, the pattern of results can also help the vet tell whether the problem starts in the pituitary gland in the brain or in an adrenal gland. Timing matters, so the vet plans the test, gives the injection and takes the samples; the lab only tests them. Stress, other illnesses and steroid medicines can change the result. A registered veterinarian reads the result together with your pet's signs, history and other tests, and may add an ACTH stimulation test, a urine cortisol test (UCC ratio) or an ultrasound scan.
How to prepare
Your vet plans the day, tells you whether to withhold food and asks about all medicines, especially steroids; your pet usually stays at the clinic so each sample is taken on time. The lab confirms the method, sample needs and reporting time when you book.
Reading the result
A registered veterinarian reads all the cortisol results together with your pet's signs, history and other tests. Stress, other illnesses and some medicines can make the result look abnormal, and no single test suits every case, so your vet may repeat the test or add an ACTH stimulation test, a UCC ratio or an ultrasound scan.
Questions about LDDST
What is the LDDS test for Cushing's disease in dogs?
Why does my dog have to stay at the clinic for most of the day?
Can stress or another illness affect the LDDST result?
What is the difference between the LDDST and the ACTH stimulation test?
Before you book this test
Why this notice: so you know, before you book, how a test is done, what its limits are and who is responsible.
- Where it is tested. Some tests are done wholly or partly by an independent partner laboratory. The lab tells you before booking if this test is sent out, and the report names the laboratory that did it.
- What a result can and cannot tell you. No test is right every time. A normal result does not rule out every disease, and an abnormal result does not prove one. A registered veterinarian should read the report with the animal’s signs and history before any treatment is started, changed or stopped.
- The sample. A sample that is clotted, too small, wrongly labelled, leaking or too old may be rejected or reported with a note, and the lab may ask for a fresh one.
- Reporting time. Confirmed when you book. Times are estimates, not guarantees, and the lab confirms the time when you book.
- Emergencies. A booking or a pending report must not delay urgent care. If an animal has collapsed, struggles to breathe, has fits or bleeds heavily, call a veterinarian at once.
Please read our Terms of Service, Medical Disclaimer, Privacy Policy and Refund and Cancellation Policy. Pashupatinath Vet Lab is operated by Duaji Healthcare and Tech Private Limited. This page is general information and does not replace a veterinarian’s advice.
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LDDST: Bhopal and the big cities of Madhya Pradesh
Free sample collection anywhere in Bhopal. From the other cities, send the sample by courier, bus parcel or through your local veterinarian, and the report comes to you online.
Free collection in these Bhopal areas
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Cushing's and Addison's Disease: Cortisol and ACTH Tests
Cushing's disease means a dog makes too much of the hormone cortisol, and Addison's disease means it makes too little. Cortisol and ACTH blood tests, with a stimulation or suppression test, help a vet tell them apart from other illnesses.
18 Oct 2026