Cardiopulmonary effects of oral trazodone administration prior to isoflurane anesthesia in healthy horses.

This research study assessed the impact of orally administered trazodone on the cardiopulmonary responses of healthy horses before they undergo isoflurane anesthesia. Findings indicate that trazodone resulted in varied heart function, with one horse experiencing significant cardiac depression.

Research Methodology

• The researchers designed a randomized, controlled trial for which 12 healthy horses assigned for euthanasia were recruited. These horses were scheduled for euthanasia due to reasons unrelated to their cardiovascular health.
• The horses were randomly allocated into two groups. One group was administered trazodone (7 horses), while the other received corn syrup (5 horses) as a control, one hour before undergoing sedation.
• The sedation process used xylazine, ketamine, and propofol. Once sedated, the horses were subjected to anesthesia using inhaled isoflurane.
• During the last 15 minutes of anesthesia, dobutamine was administered intravenously before the horses were put down.

Data Collection and Analysis

• The crucial outcome measured was the Cardiac Index (CI), measured using the saline thermodilution technique. It was recorded at various stages, including at the beginning, after oral dosing, post-sedation and induction, and at 15-minute intervals while under anesthesia.
• A mixed model was utilized to compare the data between the two groups.
• All the 12 horses completed the study as per the design.

Findings of the Study

• Overall, the study found no significant differences between the trazodone and control groups at all except one time point
• After the infusion of dobutamine, the CI was found to be significantly higher in the trazodone group as compared to the control group.
• However, in one instance, a horse from the trazodone group started showing signs of colic after the dosage, followed by a significant drop in CI during anesthesia. This was markedly reduced compared to the rest of the horses in the study.

Conclusion

• Oral administration of trazodone as a pre-anesthetic medication in healthy horses resulted in variable cardiovascular function. In one case, a horse experienced profound cardiovascular depression.
• These findings suggest that individual horses might react differently, with some showing severe cardiovascular responses when trazodone is used as a routine pre-anesthetic.