Effect of Methadone Combined With Acepromazine or Detomidine on Sedation and Dissociative Anesthesia in Healthy Horses.

The research explores the effect of combining Methadone with either Acepromazine or Detomidine on the sedation quality and influence of dissociative anesthesia in healthy horses. The findings suggest that both drug combinations produce good sedation and quality of anesthesia with Methadone and Detomidine providing better cardiopulmonary stability.

Study Design and Methodology

• The objective of this study was to examine the effects of combining methadone with two different drugs — detomidine or acepromazine – on the level and quality of sedation in healthy horses and how this affects dissociative anesthesia.
• The study was conducted using a crossover design with seven horses which were given either 0.1 mg/kg methadone and 0.02 mg/kg detomidine (known as group MD) or 0.1 mg/kg methadone and 0.05 mg/kg acepromazine (group MA) through an intravenous method.
• After these dosages were administered, anesthesia was introduced through a combination of 2.2 mg/kg ketamine and 0.1 mg/kg midazolam also via intravenous method.

Measurement and Evaluation

• The researchers evaluated the quality of sedation, induction, anesthesia maintenance, and recovery through descriptive scales and footages.
• Physiological parameters, arterial blood gas, and electrolytes were monitored from the baseline point until the recovery of the anesthesia.

Findings and Conclusion

• The study found that the group given the methadone and acepromazine mixture had lower arterial blood pressure and a higher heart rate than the methadone and detomidine group. A minor decrease in arterial blood oxygen levels was noted after the horse’s recumbency (lying down), most noticeable in the MA group.
• However, there were no differences noted in the level or timing of induction, maintenance, or recovery of anesthesia between the groups.
• The results suggest that both combinations of drugs offer good sedation and quality of anesthesia.
• However, the combination of methadone and detomidine demonstrated better cardiopulmonary stability, making it a potentially safer premedication choice for dissociative anesthesia than methadone and acepromazine in healthy horses.