Clinical applicability of detomidine and methadone constant rate infusions for surgery in standing horses.

The research is about determining the appropriate infusion rates of detomidine and methadone for sedating horses and ponies during elective surgery; results showed that an effective sedation level with minimal adverse effects was achieved, with dental procedures requiring higher detomidine rates.

Research Methodology

• The research was a prospective clinical study involving adult, healthy, client-owned non-food-producing horses or ponies. These animals were sedated for elective standing surgeries that last more than 45 minutes.
• A detomidine infusion was administered, with loading dose of 5 μg per kg, and initial rate of 12.5 μg per kg per hour, was added to a constant infusion of methadone which had dose of 0.2 mg per kg and 0.05 mg per kg per hour.
• The assessment of ataxia, sedation conditions, and surgical conditions were evaluated before the administration of sedative agents (baseline) and at different intervals: 10 minutes post sedation and every 5 minutes onward. These conditions were scored from 0-3, and used to adjust the detomidine infusion rate, through the Ghent Sedation Algorithm.
• The conditions of the surgeries were evaluated by the main surgeon using a 10-cm visual analogue scale (VAS).
• Vitals such as heart rate, systolic arterial pressure, and respiratory frequencies were recorded at each time point.
• For statistical analysis, the use of Analyses of Variance (ANOVA) for normal variables, Kruskal-Wallis H-test for non-normal variables, and Mann-Whitney U test for VAS were supportive in this study.

Findings

• Out of 42 horses/ponies included in this study, 701.00% underwent dental procedures while the remainder had other types of surgeries.
• Dental procedures required a mean higher rate of detomidine (16.9 ± 4.5 μg per kg per hr) compared to the rate used in other surgeries (9.0 ± 1.9 μg per kg per hr)
• The VAS scores for the adequacy of sedation during the surgeries did not significantly differ between the dental and other types of procedures. The median range for dental procedures was 7.8 (from 5.8 to 10), and for other procedures, it was 8.7 (from 2.8 to 10).
• There were no clinically significant changes in the cardiovascular parameters of the animals during and after surgery.
• There were also no observed behavioural changes or signs of abdominal pain in the horses and ponies postoperatively.

Conclusions

• The study concluded that effective and safe sedation for standing surgeries in horses and ponies can be achieved using a combination of detomidine and methadone infusions with locoregional anaesthesia.
• It was also noted that dental procedures require higher dose rates of detomidine infusion compared to other types of surgeries.