Plasma concentration, cardiorespiratory and analgesic effects of ketamine-fentanyl infusion in dogs submitted to mastectomy

Abstract

Abstract Background The analgesic and cardiorespiratory effects of ketamine, fentanyl, or ketamine-fentanyl constant rate infusion (CRI) in dogs undergoing mastectomy were evaluated. Seventeen female dogs received CRI of ketamine (GK [n = 6]: bolus 0.5 mg/kg; CRI 20 µg/kg/min in intra- and postoperative periods], fentanyl (GF [n = 5]: bolus 20 µg/kg; intraoperative CRI 5 20 µg/kg/hour and postoperative CRI 2 20 µg/kg/hour), or combination of ketamine-fentanyl (GKF [n = 6]: aforementioned doses) for 8 h. Cardiorespiratory, blood gas analyses, plasma drug concentrations, sedation score (SS), Pain Scores were evaluated. Results The heart rate decreased in the GF and GKF (p 100 ng/mL in 5/5 and 2/5 animals in the GKF and GK, respectively; and > 1.1 ng/mL of fentanyl in 4/5 and 3/5 in GKF and GF, respectively. Conclusion Ketamine with/without fentanyl provided analgesia without significant cardiorespiratory and guaranteed the minimal plasma levels with analgesic potential during the 8 h.

Keywords

• Analgesia
• Constant rate infusion
• Mechanical nociceptive threshold
• Pharmacokinetics