Table 3.

Protocols for dynamic testing in donkeys with pituitary pars intermedia dysfunction.

Test	TRH Stimulation Test	DST *
Protocol	Fasting has no influence. Collect at any time of the day. Avoid sampling acutely laminitic, stressed or ill animals, or after exercise or sedation with α2-agonists. Collect baseline blood sample for resting ACTH a (TRH) or cortisol b (DST) determination.
	Administer protirelin (synthetic TRH) or chemical-grade TRH: 0.5–1 mg/IV.	Administer dexamethasone: 40 µg/kg/IM.
	Second blood sample at 10 min.	Second blood sample at 15–19 h.
Interpretation	PPID if ACTH is higher than 110 pg/mL.	PPID if cortisol is higher than 1 µg/mL.
Observations	a EDTA tubes are preferable for ACTH; however; check with the laboratory for collection instructions. Rapidly centrifuge and freeze plasma. Ship under refrigeration. b Check with the reference laboratory whether plasma or serum is preferred for measurement.

* False negatives can be observed, only recommended when protirelin is not available. DST, dexamethasone suppression test; TRH, thyrotropin-releasing hormone.