Comparison of systemic atracurium, retrobulbar lidocaine, and sub-Tenon's lidocaine injections in akinesia anad mydriasis iin dogs

Abstract

Objective : To compare the effect of sub-Tenons lidocaine injections (ST) on akinesiaand mydriasis to those of systemic atracurium (AT) and retrobulbar lidocaine injectionsin dogs. Animal studied : Ten healthy beagle dogs without apparent ocular disease. Procedures : Three treatments were performed on 10 beagle dogs with a minimum7-day washout period: intravenous injection of AT (0.2 mg/kg, AT group); retrobulbar(RB) injection of 2% lidocaine (2.0 mL, RB group) in one eye; and sub-Tenons injectionof 2% lidocaine (2.0 mL, ST group) in the opposite eye. When the akinesia wasnot obtained within 10 min, an additional 1 mL of lidocaine was administered in theRB and the ST groups. Results : Onset of akinesia in the AT (1.5 0.9 min) and the ST (3.8 5.8 min)groups was significantly shorter than that in the RB group (9.0 6.5 min). Durationof akinesia in the ST group (116.2 32.8 min) was longer compared to the AT(60.6 23.6 min) and the RB (89.0 52.8 min) groups, even though there was onlya significant difference between the AT and the ST groups. Mydriasis was achieved infive eyes in the RB group and nine eyes in the ST group. There was no significant differencein onset (3.6 3.1 and 2.9 2.3 min, respectively) or duration (91.4 31.9and 102.1 35.8 min, respectively) of mydriasis between the groups. Conclusions : Sub-Tenons lidocaine injections provide excellent akinesia and mydriasiscompared to systemic AT and retrobulbar lidocaine injections. Therefore, sub-Tenons anesthesia could be an alternative to the systemic administration of neuromuscularblockers and retrobulbar anesthesia for ophthalmic surgery in dogs.