Evaluation of different doses of propofol in xylazine pre-medicated horses.

This study was aimed at characterizing the reactions in horses pre-medicated with xylazine when administered different doses of propofol. The results showed that the anaesthetic quality varied with different propofol doses; a dose of 2 mg kg-1 delivered the most desired effects, which were comparable to ketamine administration.

Research Methodology

• The experiment was done using six adult horses, five females and one male. Each horse underwent anesthesia four times in random order at one-week intervals. The anesthetics used were either ketamine or propofol.
• Prior to administering anesthetics, the horses were pre-medicated with xylazine at a dosage of 1.1 mg kg-1, given intravenously over a minute. Five minutes post this, anesthesia was induced using either ketamine (2.2 mg kg-1) or propofol (at dosages of 1, 2 and 4 mg kg-1).
• Data such as Electrocardiogram (ECG), arterial pressure, respiratory rate, pH, O2 saturation and PaO2 and PaCO2 levels were collected constantly after xylazine administration and at intervals of 5, 10 and 15 minutes after inducing anesthesia.
• The quality and recovery duration of anesthesia were both qualitatively and quantitatively assessed.

Research Findings

• There were differences in the quality of anesthesia; propofol in low dosages resulted in a poor quality anesthetization that could not facilitate intubation, while in high dosage it offered an excellent quality of induction free from excitement.
• The duration of anesthesia recorded were similar between ketamine and 2mg kg-1 dosage of propofol, with the recovery time being longer in high propofol dosages and shorter in low dosages.
• The time taken by the horses to regain their sternal and standing positions was the longest when administered with the highest dosage of propofol.
• Both ketamine and propofol were found to reverse bradycardia, atrioventricular blocks, and sinoatrial blocks produced by xylazine.
• No significant changes in blood pressure were observed. However, all groups showed significant reduction in respiratory rate, and PaO2 and O2 saturation levels.

Conclusions

• The quality of anesthesia differed with varying dosages of propofol; the dosage of 2 mg kg-1 produced the most desirable effects, which were found to be comparable with ketamine, a commonly used anesthetic in horses.
• This study, thus, suggests that propofol, when used in appropriate dosages, can serve as an effective alternative to ketamine in horses pre-medicated with xylazine.