Effects of isoflurane anesthesia on equine liver function

Area of Science:

• Veterinary Anesthesiology
• Equine Liver Physiology

Background:

• Anesthetic effects on equine liver function require further investigation.
• Biliary excretion is a key indicator of hepatic function.

Purpose of the Study:

• To evaluate the acute effects of isoflurane anesthesia on liver function and biliary excretion in ponies.
• To compare isoflurane's impact on equine bilirubin and bile acid excretion with previous findings.

Main Methods:

• Utilized ponies with chronic external biliary fistulas for direct bile collection.
• Maintained enterohepatic circulation and bile flow via intravenous bile acid infusion.
• Administered isoflurane anesthesia (1.3-1.5 MAC) for 2 hours with spontaneous breathing.

Main Results:

• Isoflurane significantly increased packed cell volume (PCV) by 27% and biliary bilirubin excretion by 24%.
• No significant changes were observed in plasma/biliary bilirubin, bile acid concentration/excretion, bile flow, or AST.
• Compared to halothane, isoflurane showed a less pronounced enhancement of bilirubin excretion.

Conclusions:

• Isoflurane anesthesia has a modest enhancing effect on hepatic bilirubin excretion in ponies.
• Isoflurane does not significantly impact equine bile acid transport or bile formation.
• Isoflurane appears to be a safer anesthetic option regarding equine liver function compared to halothane.