The use of sub-Tenon's anesthesia versus a low-dose neuromuscular blockade for canine cataract surgery: A comparative study of 224 eyes.

OBJECTIVE: Assess the utility of a Sub-Tenon's anesthesia (STA) protocol to provide suitable operating conditions for canine cataract surgery and compare it to an alternative low-dose neuromuscular blockade (LD-NMB) protocol used for canine cataract surgery. PROCEDURES: Clinical study of dog eyes undergoing cataract surgery with either an STA or LD-NMB protocol. While intraoperative vitreal expansion scores and intraoperative complications were collected prospectively, globe position, intraocular pressure, return of vision, and postoperative complications were collected retrospectively. Statistical testing was used to compare results between the STA and the LD-NMB groups for the data available. RESULTS: A total of 224 eyes from 126 dogs were assessed, with 133/224 (59.4%) eyes from 99/126 (78.6%) dogs receiving STA and 91/124 (40.6%) eyes from 72/126 (57.1%) dogs receiving LD-NMB. Forty-five of these dogs (45/126; 37.7%) received STA for one eye and LD-NMB for the other eye. There was no significant change in intraocular pressure measurements following STA administration. This was not measured for the LD-NMB group. The globe achieved a central position in 110/133 (82.7%) of eyes that received STA. This was not measured for the LD-NMB group. Intraoperative vitreal expansion scores were slightly higher in STA-treated eyes compared to LD-NMB-treated eyes. The intraoperative complication rate for STA-treated eyes was higher (73/133; 54.8%) compared to NMB-treated eyes (12/91; 13.2%). The most common intraoperative complication for STA was chemosis (64/133; 48.1%), the risk of which increased with an increase in the volume of local anesthetic injected. The post-operative complication rate was higher in STA-treated eyes (28/133; 21.1%) compared to NMB-treated eyes (16/91; 17.6%). Post-operative corneal ulceration was the most common postoperative complication in STA-treated eyes (6/133; 4.5%). CONCLUSION: The STA protocol described resulted in suitable operating conditions, but more intraoperative and postoperative complications compared to the LD-NMB protocol. Despite these complications, the STA protocol did not cause a significant deleterious impact on post-operative outcomes as defined in the present study.