Lignocaine and phenylephrine spray prior to brachycephalic obstructive airway syndrome surgery in dogs reduces postoperative regurgitation: a prospective, randomized, controlled trial

Objective: To evaluate the effect of a novel locoregional vasoconstrictive anesthesia technique on opioid requirements and postoperative complications for brachycephalic dogs undergoing surgery for brachycephalic obstructive airway syndrome. Methods: A prospective, randomized, blinded, controlled clinical trial was performed. A total of 98 brachycephalic dogs presenting to a single referral hospital from July 2024 to November 2025 for elective airway surgery were prospectively enrolled. Subjects were randomized to receive 10 actuations of lignocaine and phenylephrine spray or placebo via intraoral administration prior to surgery. A standardized protocol designed for brachycephalic dogs undergoing surgery was utilized for anesthetic management. Outcome measures including intraoperative and postoperative interventions, as well as postoperative complications, were compared. A directed acyclic graph was constructed to determine any causal relationships. Results: 49 dogs received intraoral lignocaine and phenylephrine spray and 49 dogs received placebo spray prior to surgery. Intraoperative and postoperative methadone requirements did not differ significantly between treatment groups. No difference in postoperative respiratory complications was found, but postoperative regurgitation was significantly higher in the placebo group compared to the lignocaine group (OR, 8.1; 95% CI, 2.5 to 37.0). Conclusions: Intraoral lignocaine and phenylephrine spray did not reduce intraoperative opioid requirements but did decrease postoperative regurgitation. Clinical Relevance: To reduce gastrointestinal complications, locoregional vasoconstrictive anesthesia techniques should be considered as part of a multimodal anesthesia plan for dogs undergoing corrective surgery for brachycephalic obstructive airway syndrome.