Clinical, cytological, and microbiological evaluation of a topical boric acid-alcohol solution for the treatment of canine otitis externa: A randomized, open-label controlled clinical trial

Abstract

Otitis externa (OE) is a common inflammatory condition frequently encountered in veterinary practice. This study aimed to evaluate the efficacy of a topical 5% boric acid-alcohol (BAA) solution compared to a commercial ear cleanser (EpiOtic (R)) for treating canine OE. Thirty client-owned dogs with OE were enrolled in a randomized, open-label controlled clinical trial and assigned to two treatment groups: Group I received BAA combined with EpiOtic (R), and Group II received EpiOtic (R) alone, both applied twice daily for 14 days. Clinical assessments-including OTIS-3 scoring, secretion type, otoscopic findings, pain, pruritus, and cytology-were performed on days 0, 7, 14, and 21, with microbiological analyses on days 0 and 21. By day 21, treatment success was achieved in 93.3% of Group I dogs, compared to 26.7% in Group II (p < 0.001). Group I showed significant improvements in all clinical parameters (p <= 0.001), while Group II exhibited only modest changes. Cytology showed significantly better results in Group I on days 7 (p = 0.002), 14, and 21 (both p < 0.001), with cytological success rates of 93.3% vs. 20% in Group II. By day 21, microbiological analysis demonstrated complete fungal eradication and near-complete bacterial clearance in Group I, with cultures confirming elimination of common pathogens including Staphylococcus intermedius, Proteus mirabilis, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Malassezia pachydermatis. These findings indicate that BAA is a safe, effective, and economical alternative for managing canine OE and may contribute to antimicrobial stewardship by reducing the need for systemic therapies.