Minimum end-tidal sevoflurane concentration necessary to prevent movement during a constant rate infusion of morphine, or morphine plus dexmedetomidine in ponies.

Objective: To compare the effects of a constant rate infusion (CRI) of dexmedetomidine and morphine to those of morphine alone on the minimum end-tidal sevoflurane concentration necessary to prevent movement (MACNM ) in ponies.

Study Design: Prospective, randomized, crossover, 'blinded', experimental study.

Animals: Five healthy adult gelding ponies were anaesthetized twice with a 3-week washout period.