Unilateral retrobulbar hematoma following maxillary nerve block in a dog

To describe the clinical findings and management of a case of retrobulbar hematoma formation secondary to performance of a maxillary nerve block in a dog.

An 11-year-old dog was presented for a routine dental procedure including dental extraction to be performed under general anesthesia. After premedication with intramuscular methadone, anesthesia was induced with intravenous alfaxalone until depth of anesthesia was sufficient to allow orotracheal intubation. Anesthesia was maintained with isoflurane delivered in 100% oxygen. A bilateral maxillary nerve block was performed. During administration of the left nerve block, blood was aspirated. Twenty minutes after placement of the left maxillary nerve block, exophthalmos, periorbital swelling, extensive scleral hemorrhage, and ecchymosis with a 2 × 2 cm region of moderate swelling on the palatal mucosa around the injection site were noted. These lesions were the result of retrobulbar hematoma formation following vessel puncture. Treatment included immediate creation of a drainage tract and administration of anti-inflammatories (carprofen 2 mg/kg PO q 12 h for 7 days), broad spectrum antimicrobial therapy (cefovicin 8 mg/kg SC once), and eye drops (viscotears, 2 drops OS q 12 h for 7 days). The periorbital swelling was significantly reduced within 1 hour of drainage and had almost completely resolved 1 week later.

This clinical report details the development and successful management of a unilateral retrobulbar hemorrhage following maxillary nerve block. Management of this condition requires prompt recognition and treatment to prevent permanent damage to the eye. The cornerstone of treatment is drainage, which rapidly decreases the increased intraorbital and intraocular pressure. To our knowledge, this is the first documentation of this complication in the English language literature.