Epidural anesthesia and postoperatory analgesia with alpha-2 adrenergic agonists and lidocaine for ovariohysterectomy in bitches.

The aim of this study was to determine the viability and cardiorespiratory effects of the association of epidural alpha-2 adrenergic agonists and lidocaine for ovariohysterectomy (OH) in bitches. Forty-two bitches were spayed under epidural anesthesia with 2.5 mg/kg body weight (BW) of 1% lidocaine with adrenaline (CON) or in association with 0.25 mg/kg BW of xylazine (XYL), 10 μg/kg BW of romifidine (ROM), 30 μg/kg BW of detomidine (DET), 2 μg/kg BW of dexmedetomidine (DEX), or 5 μg/kg BW of clonidine (CLO). Heart rate (HR), respiratory rate (fR) and arterial pressures were monitored immediately before and every 10 min after the epidural procedure. Blood gas and pH analysis were done before, and at 30 and 60 min after the epidural procedure. Animals were submitted to isoflurane anesthesia if they presented a slightest sign of discomfort during the procedure. Time of sensory epidural block and postoperative analgesia were evaluated. All animals in CON and DEX, 5 animals in ROM and CLO, 4 animals in XYL, and 3 in DET required supplementary isoflurane. All groups, except CLO, showed a decrease in HR. There was an increase in arterial pressures in all groups. Postoperative analgesia lasted the longest in XYL. None of the protocols were totally efficient to perform the complete procedure of OH; however, xylazine provided longer postoperative analgesia than the others.