Use of halothane and isoflurane in the horse.

The study compares the effects of two anesthetics, halothane and isoflurane, on horses. It finds that while the two drugs have similar effects on eye reflexes and blood pressure, isoflurane requires higher vaporizer settings and causes slower respiratory rates but quicker intraoperative changes and recovery.

Anaesthetic Potency and Settings

• Isoflurane required higher settings on the vaporizer compared to halothane. The researchers attribute this need to isoflurane’s lower potency.

Respiratory Rates

• When using isoflurane, horses’ respiratory rates will be slower than when halothane was used. Changes in respiratory rates are crucial in monitoring animal health during and after surgery.

Anaesthetic Depth and Recovery Speed

• Despite its lower potency, isoflurane allowed more rapid changes in the depth of anaesthesia during surgery, and faster recovery from surgical depth of anesthesia. This implies that isoflurane may be preferred in situations where rapid changes in anesthetic depth are necessary or beneficial.
• However, total recovery times were often similar, suggesting that while isoflurane may speed early recovery, it doesn’t necessarily shorten the total recovery period.

Effects on Ocular Reflexes and Blood Pressure

• There were no observable differences between halothane and isoflurane in their impacts on horses’ ocular reflexes and mean arterial blood pressure. Both of these parameters are significant when monitoring an animal under general anesthesia.

Managing Recovery from Isoflurane

• The researchers advised on the need to manage recovery from isoflurane anesthetic carefully. This is particularly important to prevent horses from attempting to stand prematurely. The administration of added sedation or physical support may be required to ensure safe recovery.