Diagnosing Cushing’s syndrome in dogs is a familiar challenge in practice. The process can be expensive, time-consuming and stressful, often requiring a full day in hospital for intravenous testing. A new open-access study published in Animals has explored whether that diagnostic burden could be reduced without losing accuracy, by evaluating an oral, at-home version of the low-dose dexamethasone suppression test (LDDST).
The methodology
The researchers assessed an approach where dexamethasone is given orally by the owner at home, and diagnosis is based on the urinary corticoid-to-creatinine ratio (uCC) rather than serial blood samples. Urine was collected at baseline and again eight hours after dexamethasone administration, aiming to capture cortisol suppression in a lower-stress environment.
The study included 168 dogs from a single referral endocrinology centre, divided into healthy controls, dogs with diseases that can mimic Cushing’s, and dogs with confirmed hyperadrenocortisism.
Using an eight-hour uCC cut-off, the authors reported a sensitivity of around 95% and specificity of around 93%, with diagnostic performance comparable to established tests. Owner response to the protocol was positive, with the majority preferring the at-home oral test to the traditional intravenous LDDST.
Limitations
However, the study also has important limitations that are relevant for vets considering this approach. It was conducted at a single referral centre, and performance in first-opinion practice — where cases may be earlier, milder or complicated by concurrent disease — may differ. The test also does not distinguish pituitary-dependent from adrenal-dependent disease, meaning further testing and imaging would still be required after diagnosis. In addition, the authors stress that uCC cut-off values are assay- and laboratory-specific, so results cannot simply be transferred without local validation.
Key takeaway
For vets and nurses in practice, this study suggests that an at-home oral LDDST could become a useful addition to the diagnostic toolkit, particularly for anxious dogs or owners who struggle with the logistics or costs of a day-long hospital stay. Reducing venepuncture, cage occupancy and staff time while maintaining diagnostic quality would be a clear benefit in many cases. However, successful use would depend heavily on clear client instructions, reliable urine collection, and close collaboration with diagnostic laboratories.
The full study can be found here: Urinary Corticoid-to-Creatinine Ratio 8 Hours After Low-Dose Oral Dexamethasone for the Diagnosis of Cushing’s Syndrome in Dogs
