Hemodynamic function during neurectomy in halothane-anesthetized horses with or without constant dose detomidine...

Area of Science:

• Veterinary Anesthesia
• Equine Surgery
• Cardiovascular Physiology

Background:

• Acepromazine, guaifenesin, and thiamylal are commonly used for equine anesthesia induction.
• Halothane is a volatile anesthetic agent used for maintenance.
• Detomidine is an alpha-2 adrenergic agonist with sedative and analgesic properties.

Purpose of the Study:

• To compare the effects of halothane-only anesthesia versus halothane with detomidine infusion on hemodynamic and respiratory parameters in horses.
• To evaluate anesthetic maintenance regimens during surgical manipulation of digital nerves.

Main Methods:

• Nine horses were premedicated with acepromazine and induced with guaifenesin and thiamylal.
• Anesthesia was maintained with either halothane in oxygen or halothane in oxygen plus a detomidine infusion.
• Hemodynamic and respiratory measurements were recorded throughout anesthesia and surgical procedures.

Main Results:

• Horses receiving detomidine had a significantly higher heart rate compared to the halothane-only group.
• Respiratory rate increased during surgical stimulation.
• Arterial blood pressure increased during surgery, peaking during neurectomy, associated with increased systemic vascular resistance and decreased cardiac output.

Conclusions:

• Detomidine infusion with halothane anesthesia in horses did not significantly alter most hemodynamic parameters compared to halothane alone, but improved heart rate.
• Increased blood pressure during surgery is likely due to increased systemic vascular resistance, potentially with decreased cardiac output.
• These findings suggest detomidine can be a valuable adjunct for maintaining cardiovascular stability during equine surgery.