Romifidine, medetomidine or xylazine before propofol-halothane-N2O anesthesia in dogs

The objective of this paper was to evaluate romifidine as a premedicant in dogs prior to propofol-halothane-N2O anesthesia, and to compare it with the other alpha(2)-agonists (medetomidine and xylazine). For this, ten healthy dogs were anesthetized. Each dog received 3 preanesthetic protocols: atrop ine (10 mu g/kg BW, LM), and as a sedative, romifidine (ROM; 40 mu g/kg BW, IM), xylazine (XYL; 1 mu g/kg, IM), or medetomidine (MED; 20 mu g/kg BW, I M). Induction of anesthesia was delivered with propofol 15 min later and ma intained with halothane and N2O for one hour in all cases. The following va riables were registered before preanesthesia, 10 min after the administrati on of preanesthesia, and at 5-minute intervals during maintenance: PR, RR, rectal temperature (RT), MAP, SAP, and DAP. During maintenance, arterial ox ygen saturation (SpO(2)), end-tidal CO2 (EtCO2) and percentage of halothane necessary for maintaining anesthesia (%HAL) were also recorded. Induction dose of propofol (DOSE), time to extubation (TE), time to sternal recumbenc y (TSR) and time to standing (TS) were also registered. The statistical ana lysis was carried out during the anesthetic period. ANOVA for repeat measur es revealed no differences between the 3 groups for PR and RR; however, MAP , SAP and DAP were higher in the MED group; SpO(2) was lower in MED and EtC O2 was lower in ROM; %HAL was higher in XYL. No statistical differences wer e observed in DOSE, TE, TSR or TS. Percentage of halothane was lower in rom ifidine and medetomidine than in xylazine premedicated dogs also anesthetiz ed with propofol. All the cardiorespiratory variables measured were within normal limits. The studied combination of romifidine, atropine, propofol, h alothane and N2O appears to be a safe and effective drug combination for in ducing and maintaining general anesthesia in healthy dogs.