# Perioperative analgesic effects of a modified supratemporal retrobulbar block in dogs undergoing corneal and endocular surgery

## TL;DR

A modified supratemporal retrobulbar block in dogs undergoing eye surgery reduces the need for additional pain medication and improves recovery quality.

## Contribution

The study introduces a modified supratemporal retrobulbar block technique that effectively provides perioperative analgesia in canine ocular surgery.

## Key findings

- Dogs receiving the retrobulbar block had significantly less need for fentanyl compared to controls.
- The retrobulbar group showed improved recovery scores and no postoperative eye rubbing.
- The block reduced the median amount of fentanyl administered during surgery.

## Abstract

To evaluate the perioperative efficacy of a modified supratemporal retrobulbar block in dogs undergoing ocular surgery.

In this prospective randomised clinical trial, dogs were premedicated with dexmedetomidine (1 mcg/kg im) and methadone (0.1 mg/kg im), induced with propofol to effect and maintained with isoflurane (FE'Iso 1.1%). In the retrobulbar group a mixture of lidocaine 2% (5.5 mL) and ropivacaine 0.75% (2 mL) was administered at 0.1 mL/kg, via a modified supratemporal technique using a Tuohy needle. No block was performed in the controls. When heart rate or mean arterial pressure increased above 30% of the pre‐incisional values, fentanyl (1 mcg/kg iv) was administered. Propofol (1 mg/kg iv) was injected when anaesthesia was deemed too light. After a total of three administrations regardless of the type of drugs (fentanyl/propofol), a constant rate infusion of fentanyl (5 mcg/kg/h iv) was started. Quality of recovery (blindly assessed using a descriptive score scale), postoperative eye rubbing and complications were studied.

Eighteen dogs were included. The retrobulbar group (nine) dogs had significantly less risk of receiving fentanyl than controls (nine) (Relative risk:  0.142, 95% CI: 0.021 to 0.936) and a recovery score > 2 (RR: 0.058, 95% CI: 0.003 to 0.887). The median amount of fentanyl (mcg/kg) was statistically lower in the retrobulbar group than in the controls: 0 mcg/kg (range, 0 to 1) versus 2 mcg/kg (range, 0 to 8.49), respectively. Only controls showed eye rubbing.

The modified supratemporal retrobulbar block reduced the intraoperative rescue analgesia and improved the quality of recovery.