34th Annual Scientific Meeting proceedings

Five horses of varying age and breed underwent blind extraperiorbital fat body insertion technique (EFBI) for maxillary nerve anaesthesia to assist in standing exodontia. Previous reports of complications secondary to excessive volume have been reported; these include Horner’s syndrome, exophthalmos, or face swelling.

A blind EFBI was used with 20ml of mepivacaine hydrochloride. All five horses developed clinical signs during the following 30 minutes after regional analgesia had been performed. The oral exodontia was performed successfully in all cases. The signs were consistent with paresis of the oculomotor nerve: most notably a persistent mydriasis and alacrima. One of the horses developed persistent paresis of the palpebral branch of the auriculopalpebral nerve. No further deficit of the facial nerve was seen, this horse did not show any oculomotor deficit. All cases received profilactic treatment; only the horse with facial nerve involvement developed a corneal ulcer, which was treated topically. The ulcer was successfully treated. This resolved completely once the eyelid returned to its normal function.  For the other horses, all clinical signs were transient (<12hours), and all horses made a complete recovery.

This case series highlights the risk of inadvertently affecting adjacent nervous structures associated with the blind EPOFB with the addition of complications that have not been previously reported. The ultrasound guided technique may reduce the complication rate.

Other alternatives such as the use of intraligamentous infiltration of local anaesthetic may provide sufficient analgesia for the exodontia. Lower volumes may reduce the complication rate after performing regional analgesia through an EFBI.