Feasibility of Enucleation in Standing Sedated Horses With Retrobulbar Anesthesia and Auriculopalpebral Nerve Block: Impact of Ultrasound Guidance in a Case Series

ABSTRACT Objective Examining the feasibility of enucleation in standing sedated horses with dorsal retrobulbar anesthesia (RBA) and auriculopalpebral (AP) nerve block and the impact of ultrasound (US) guidance on RBA success. Animals Studied Thirty horses. Procedures In a prospective clinical case series, horses ( n = 15/group) received standardized sedation, dorsal RBA (12 mL mepivacaine) and AP nerve block (4 mL lidocaine). Group 1 received US‐assisted RBA (10 MHz linear probe), Group 2 underwent blind RBA subsequently. Needle positioning time was recorded. Eyelid sensitivity was measured before ( t 0 ) and 20 min after injection ( t 20 ). RBA success was defined as surgical tolerance at t 20 . US image quality (excellent/good/poor) was assessed and compared with RBA success. If RBA failed, additional local anesthetic was injected. Results RBA success was 63.4% (19/30) with 73.3% (11/15) in Group 1 and 53.3% (8/15) in Group 2 ( p = 0.179). 3/19 successful cases required additional retrobulbar anesthetic top ups intraoperatively ( t 60 – t 80 ). A significant association was found between the number of successfully anesthetized lid areas per horse and RBA success ( p < 0.001). Mean time for US‐assisted RBA was 5.2 min (±1.7 min). US image quality was rated as “excellent” in 3/15, “good” in 7/15, and “poor” in 5/15 cases, with corresponding success rates of 100% (3/3), 85.7% (6/7), and 40% (2/5), respectively. Improved US image quality showed a non‐significant trend toward higher success ( p = 0.053). Conclusion RBA combined with AP nerve block provides adequate anesthesia for standing equine enucleation. US image quality and eyelid sensitivity are suitable block success predictors.