Analgesic and Cardiopulmonary Effects of Epidural Romifidine and Morphine Combination in Horses.

The research investigates the effects of combining two dosages of romifidine with morphine when administered epidurally in horses. It examines the impacts on pain relief, heart and respiratory rates, blood gases and pressures, and noxious stimulation responses.

Experimental Design and Animals

• The study used a prospective crossover blinded experimental design, which means the researchers and the subjects (in this case, horses) do not know which treatment they were receiving at each period of the experiment.
• Five adult horses, two males and three females, with an average weight of 380 ± 45 Kg, were included in the study. The weight range was 335-425 kg.

Treatment and Measurement

• The horses received epidural injections of either 30 μg/kg (R30) or 60 μg/kg (R60) romifidine combined with 0.1 mg/kg morphine, administered through an epidural catheter at the first intercoccygeal space.
• A 72-hour washout period, i.e., a break between different treatments, was established to clear out any remaining effects of the previous medication.
• Multiple parameters (including heart rate, respiratory rate, blood pH and gases, arterial blood pressures, and thresholds for electrical noxious stimulation) were measured before, every 15 minutes post-treatment for 120 minutes, and again after 240 minutes of epidural injection.

Findings

• Significant sedation, or drowsiness, was observed in the horses receiving both types of treatments. However, there was no significant difference between the effects of R30 or R60 treatments on sedation.
• There were important changes detected in the horses’ respiratory and heart rates compared to their baselines, however, no noteworthy divergence was found between the two treatments.
• Horses receiving R60 treatment showed significantly lower arterial blood pressures from 75 minutes to 120 minutes after receiving the epidural injection.
• Analgesia, or pain relief, was deemed moderate for both treatments, lasting longer in horses given 60 μg/kg of romifidine.

Conclusion

• The combination of romifidine and morphine administered epidurally in horses resulted in dose-dependent sedation, lowered arterial blood pressure and pain-relieving effects. This implies that the effectiveness of these effects vary based on the dosage of romifidine administered.