Canis ISSN: 2398-2942

Low-dose dexamethasone suppression test

Synonym(s): LDDST

Contributor(s): David Bruyette, Yvonne McGrotty


  • Administration of exogenous glucocorticoid (dexamethasone) suppresses hypothalamic-pituitary axis  .
  • Natural cortisol levels are suppressed for 78 h in normal animal.
  • Dogs with hyperadrenocorticism show breakthrough of suppression by 8 h.


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  • Widely available at commercial laboratories.



  • More reliable than ACTH stimulation test ACTH assay in confirming hyperadrenocorticism).
  • Overall sensitivity around 96.6%.
  • Lack of suppression at both 4 h and 8 h has the highest positive predictive vaule.
  • Escape or inverse patterns are associated with a lower positive predictive value.


  • Specificity 67.2%.
  • More affected by non-adrenal disease than the ACTH stimulation test.
  • Specificity is poor in dogs with non-adrenal illness or concurrent diseases (especially diabetes melllitus Diabetes mellitus).
    Do not perform adrenal function tests in ill animals.
  • Only perform LDDST in animals where there is a strong indication to do so.

Technician (extrinsic) limitations

  • Must be able to give intravenous injection and collect samples without stressing animal.

Result Data

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Further Reading


Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Bannaim M, Shiel R E, Forde C & Mooney C T (2018) Evaluation of individual low dose dexamethasone test patterns in naturally occurring hyperadrenocorticism in dogs. JVIM 32(3), 967-977 PubMed.
  • Vaessen M M A R, Kooistra H S, Mol J A & Rijnberk A (2004) Urinary corticoid:creatinine ratios in healthy pet dogs after oral low-dose dexamethasone suppression testsVet Rec 155, 518-521.
  • Feldman E C, Nelson R W, Feldman M S (1996) Use of low- and high-dose dexamethasone suppression tests for distinguishing PDH from ADH in dogs. JAVMA 209, 772-775 PubMed.
  • Chauvet A E, Feldman E C, Kass P H (1995) Effects of phenobarbital administration on results of serum biochemical analyses and adrenocortical function tests in epileptic dogs. JAVMA 207, 1305-1307.
  • Kaplan A J, Peterson M E, Kemppainen R J (1995) Effects of disease on the results of diagnostic tests for use in detecting hyperadrenocorticism in dogs. JAVMA 207, 445-451.

Other sources of information

  • Most commercial laboratories will provide information on test and interpretation of data.