# The Avian-RUM Block: A Locoregional Technique for Distal Wing Procedures in Birds—An Anatomical Cadaveric Feasibility Study with a Clinical Illustration

## TL;DR

This study introduces a new nerve block technique for bird wing surgery that is safe and effective, based on anatomical research and a clinical example.

## Contribution

The Avian-RUM block is a novel, anatomy-based locoregional technique for avian distal wing procedures, adapted from mammalian methods.

## Key findings

- The Avian-RUM block successfully stained nerves in rock doves and hooded crows with no significant difference between low and high injection volumes.
- The technique was feasible and safe, with minor interspecific anatomical differences observed.
- A clinical application in a domestic goose demonstrated the block's practical use in a real-world setting.

## Abstract

Anaesthesia in birds presents significant challenges due to high mortality rates and marked anatomical variability among species. Multimodal anaesthetic protocols, incorporating locoregional techniques, are recommended to improve analgesia and reduce systemic drug requirements. While brachial plexus blocks are commonly described for avian wing surgery, they carry risks of complications, including vascular puncture and injection into air sacs. This study introduces the “Avian-RUM block,” a novel locoregional technique for the distal wing, adapted from the mammalian RUMM block. Unlike its mammalian counterpart, the Avian-RUM block targets only the radial and median-ulnar nerves, reflecting the absence of a distinct musculocutaneous branch in birds. Using cadavers of rock doves and hooded crows, a dye solution was injected under direct transcutaneous visualisation of the nerves through the brachial skin. Both species showed high rates of nerve staining, with no significant differences between low (0.15 mL/kg) and high (0.3 mL/kg) injection volumes, suggesting that small volumes are sufficient for coverage. Minor interspecific differences reflected anatomical depth of the nerves. A clinical application in a domestic goose is also presented to contextualise the findings within a clinical setting. This approach represents a practical, anatomy-based technique that may enhance the effectiveness of avian anaesthesia across diverse settings.

Anaesthesia in avian species presents significant challenges due to high peri-anaesthetic mortality rates and marked anatomical variability. Multimodal anaesthetic protocols incorporating locoregional techniques are advocated to improve analgesia and minimise systemic drug requirements. While brachial plexus blocks are described for avian wing surgery, the proximity to major vessels and air sacs increases the risk of complications. This study introduces the “Avian-RUM block,” a novel locoregional technique for the distal wing, adapted from the mammalian RUMM block but modified to reflect avian neuroanatomy, which lacks a distinct musculocutaneous nerve. Twelve rock doves (Columba livia) and twelve hooded crows (Corvus cornix) received transcutaneous injections of a dye solution targeting the radial and median-ulnar nerves at two volumes (0.15 and 0.3 mL/kg). Both species demonstrated high rates of nerve staining and procedural feasibility, with no significant difference in staining length between volumes. An illustrative clinical application of the Avian-RUM block in a domestic goose is also reported to contextualise the cadaveric findings within a multimodal perioperative setting. The results confirm the feasibility of the Avian-RUM block and its potential as a simple, equipment-free technique for regional anaesthesia of the avian wing. These findings provide a foundation for future clinical validation across bird species.