Background: Antibiotic resistance is an increasing global threat to human and veterinary practices. The relevance and efficacy of antibiotic therapy in the treatment of various diseases has been poorly documented in the literature. One such disease is equine sinusitis secondary to dental disease where dental extraction is most often combined with broad-spectrum antibiotic treatment. It, however, remains undocumented if antibiotic treatment reduces the risk of complication in horses where the diseased tooth is removed by extraction. Objectives: The aim of this study was to analyse the effects of perioperative antibiotics in horses with dental sinusitis treated by dental extraction with or without concurrent antibiotic treatment. Study design: Retrospective cohort study. Methods: Clinical records from horses presenting with nasal discharge between September 2016 and May 2022 were reviewed. Horses with sinusitis secondary to dental disease were identified, and data from clinical records were collected supplemented by online questionnaires. The final statistical model was built using logistic regression. Results: A total of 59 horses with dental sinusitis were included in the study. Following dental extraction, 62.5% (15/24) of horses that did receive perioperative antibiotics and 60% (21/35) of horses that did not receive perioperative antibiotics were successfully treated without the need for further treatment. The final model showed no significant difference on the probability of success (p = 0.85) between treatment with and without antibiotics. Main limitations: The retrospective nature of this study may increase the risk of biases in relation to data collection and follow-up information and the limited number of individuals available for the analysis. Conclusions: These findings indicate that the use of perioperative antibiotics does not influence the likelihood of complications or the probability of a successful outcome in horses with dental sinusitis undergoing dental extraction.