1. Take a basal sample of 2ml clotted or heparinised blood after an overnight fast. (Taking the basal sample at 9 to 10a.m. will minimise the influence of diurnal fluctuations in cortisol concentration).
1. Inject dexamethasone i/v at 0.01mg/kg bodyweight. Suitable short acting preparations are listed below.
1. Take further 2ml clotted or heparinised blood samples at 3 hours and 8 hours post dexamethasone njection.
1. Mark the samples clearly and if possible separate the serum or plasma before despatch to the laboratory.

COMMENT

The dexamethasone (low dose) screening test will identify 90-95% of pituitary dependant hyperadrenocorticism (PDHAC) dogs and almost 100% of dogs with adrenal tumours. It will not reliably distinguish between the two conditions. The dexamethasone (high dose) suppression test is recommended for distinguishing between PDHAC and an adrenal tumour following a positive dexamethasone (low dose) screening test result.
 

SUITABLE DEXAMETHASONE PREPARATIONS
Azium injection	Dexamethasone	Schering - Plough Animal Health
Colvasone	Dexamethasone sodium phosphate	Norbrook
Dexadreson	Dexamethasone sodium phosphate	Intervet
Dexazone	Dexamethasone sodium phosphate	Bimeda
Duphacort Q	Dexamethasone sodium phosphate	Solvay-Duphar
Soludex injection	Dexamethasone	Mycofarm

This information is intended as a guide. Veterinary surgeons should consult the relevant data sheet before use.
 

Test Code	Test Name and Description	Sample
DSCR	Dexamethasone (Low Dose) Screening Test	3 x serum or heparin plasma

REFERENCES

Evans H and Walker M. SCL Veterinary Services Manual. 6th Edition. p.15.