The aim of this study was to compare the analgesic effects of continuous infusion of fentanyl, dexmedetomidine, or maropitant. The animals received pre-anesthetic medication and anesthetic induction. Subsequently, continuous infusion of drugs was instituted, distributed in the following groups: fentanyl, dexmedetomidine, and maropitant. During the surgical procedure, the analgesic effects were evaluated by recording the cardiorespiratory parameters at the moments of greatest pain stimulus. When evaluating analgesic effects, the maropitant group showed greater stability in cardiorespiratory parameters compared to the fentanyl and dexmedetomidine group. From this study, it is suggested that continuous infusion of maropitant has analgesic effects similar to fentanyl and greater than dexmedetomidine.