Although this seems a popular block, there have always been doubts over the efficacy due to the anatomy of the nerves that are required to be blocked to provide anaesthesia. This pain update reviews the controversy around the technique for an effective infraorbital nerve block and enables the learner to make evidence-informed decisions.
The infraorbital block, when performed at the infra-orbital foramen, is ineffective for anaesthesia of the canine tooth and caudally. Reason being, is that the nerves that convey sensory information originate from this nerve within the infraorbital canal - these nerves are the middle superior alveolar nerves, incisivomaxillary nerve & anterior superior alveolar nerve. Is there really an infraorbital canal in cats?
Our dental anaesthesia webinar covers the techniques we recommend for dental anaesthesia in both dogs and cats.
Does the literature support our understanding on this? In this study, Shilo-Benjamini and colleagues looked at three different techniques reported in cats. Two of these examined different approaches to the infraorbital nerve - one with deposition of injectate at the foramen, and one with deposition into the infraorbital canal itself.
This was a cadaver study using dye and CT imaging. The former technique produced poor distribution of dye. When the needle was inserted into the canal, dye distribution was better. Clearly one concern with the approach into the canal is penetration of the globe. The researchers examined the CT images for evidence of globe penetration and could see no evidence of this. The work was not a clinical study in live cases so the clinical efficacy is yet to be determined.
Watch our dental anaesthesia webinar in conjunction with reading this pain update. Which nerve blocks are you performing for dental cases at the moment? How do you tell that those blocks are effective? In the webinar we cover detecting nociception and give options for managing this.
Learning objectives
Understand the different approaches described to anaesthesia for feline dental work.
Appreciate there are differences of opinion around this block and further work is required.
This post was written by Matt Gurney.
Matt sees referrals in the pain clinic at Anderson Moores Veterinary Specialists. You can also receive telemedicine advice from us here if you have a pain case where you need a helping hand.
Matt & Carl established Zero Pain Philosophy to provide educational resources & telemedicine to veterinary professionals enabling optimal management of pain.
Matt Gurney is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and works at Anderson Moores Veterinary Specialists. Matt is Past President of the European College of Veterinary Anaesthesia & Analgesia.
Carl Bradbrook is an RCVS & European Specialist in Veterinary Anaesthesia & Analgesia and is Past President of the Association of Veterinary Anaesthetists. Carl works at Anderson Moores Veterinary Specialists.
The intended audience for this pain update is veterinary professionals. This pain update is based on clinical experience and independent opinion.
Reference
Shilo-Benjamini Y, Letz S, Peery D, Abu Ahmad W, Bar-Am Y. Comparison of three regional anaesthetic techniques for infraorbital or maxillary nerve block in cats: a cadaveric study. J Feline Med Surg. 2022 Apr;24(4):322-327. doi: 10.1177/1098612X211020163. Epub 2021 Jun 9. PMID: 34106793; PMCID: PMC8961245.
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