Evaluation of five common induction protocols by comparison of hemodynamic responses to surgical manipulation in halothane-anesthetized horses.

This study investigates the influence of different anesthetic induction protocols on the hemodynamic responses of horses under halothane-based anesthesia during surgery. The researchers found that the choice of induction protocol had minimal impact on the horse’s hemodynamics during surgery, although surgical procedures did produce noticeable changes.

Methods

• The researchers conducted a prospective experimental study with 36 clinically normal horses. The horses were divided into five groups, each with a different anesthetic induction protocol.
• The first group received acepromazine/guaifenesin/thiamylal, the second acepromazine/guaifenesin/ketamine, the third xylazine/guaifenesin/thiamylal, the fourth xylazine/guaifenesin/ketamine, and the last group xylazine/diazepam/ketamine as anesthetic induction mechanisms.
• Anesthesia was maintained with halothane for all the horses throughout the surgical procedures.
• The team took hemodynamic measurements and blood gas values three times in each horse: before the surgery started, during the surgical procedure, and after the surgery.

Results

• The results revealed very little variance in hemodynamic measures between the horses anesthetized with different induction protocols, regardless of whether the measurements were taken before or during the surgery.
• The surgical manipulation did elicit prominent hemodynamic responses, including an increase in mean arterial pressure and systemic vascular resistance, and a decrease in cardiac index and oxygen delivery.

Conclusions

• The study concluded that the anesthetic induction protocol plays a negligible role in determining the horse’s hemodynamic function during surgery under halothane anesthesia.
• Despite an increase in blood pressure due to surgical stimulation, there was no improvement observed in the cardiac index or oxygen delivery to the horse’s system.