Enucleation is commonly carried out in veterinary practice. These patients can benefit hugely from local anaesthetic techniques to improve operating conditions and patient comfort post-operatively. The traditional technique used is the retrobulbar block. Insertion of a needle to the back of the eye can be a little off-putting resulting in avoidance of the technique.
For the peribulbar block the local anaesthetic is injected extraconally to provide sensory blockade to the orbit and eyelids. It is indicated for enucleation and is much easier to perform that the retrobulbar technique. It is illustrated in this video.
Several approaches have been reported – a single ventrolateral injection, a single injection at the medial canthus and a double injection technique dorsomedially and ventrolaterally. A documented advantage of one over the other is yet to be made clear.
Volume of local anaesthetic required for anaesthesia is relatively high. In a cat study, 3ml was used. It is recommended that a volume of 2-10 ml for dogs and 3 ml is used for cats (Shilo-Benjamin et al 2019).
The dog in the video was premedicated with medetomidine & methadone and administered an NSAID for a multimodal zero pain approach to analgesia.
References
Shilo-Benjamini, Y. (2019). A review of ophthalmic local and regional anaesthesia in dogs and cats. Veterinary Anaesthesia and Analgesia,46(1), 14–27. https://doi.org/10.1016/j.vaa.2018.10.004