Magnesium sulfate and ketamine as analgesic and anesthetic adjuvants in total intravenous anesthesia in cats

ABSTRACT: This study assessed the efficacy of magnesium sulfate and ketamine hydrochloride in reducing the demand for propofol, remifentanil, and postoperative rescue analgesia in cats undergoing elective ovariohysterectomy. Thirty cats were premedicated with acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg) intramuscularly and induced to unconsciousness with propofol for orotracheal intubation. The continuous infusion (CI) of propofol and remifentanil were started and animals and were randomly allocated into three groups: the magnesium sulfate group (MG) received one bolus (50 mg/kg) and CI (80 mg/kg/h) of magnesium sulfate; the ketamine group (KG) received bolus (0.5 mg/kg) and CI (1.8 mg/kg/h) of ketamine hydrochloride; the control group (CG) received bolus and CI of 0.9% saline solution. Cardiovascular and respiratory functions, extubation time, and rescue postoperative scores were assessed and data were described with a significance level of 95% (P < 0.05). The infusion period of treatments was 21.5 ± 3.4 and 21.0 ± 2.4 minutes in the KG and MG, respectively (P = 0.194). The infusion rates of remifentanil (P = 0.336) and propofol (P = 0.716) were similar between groups. Analysis of the postoperative pain scales revealed no significant intergroup differences in rescue frequency, rescue score, and time to the first rescue analgesia. In conclusion, the proposed protocols were safe and effective, yet it is noteworthy that both magnesium sulfate and ketamine failed to demonstrate significant additional postoperative analgesic or adjuvant anesthetic effects.