Evaluation of hypochlorous acid as an ear flush in dogs with chronic otitis externa

Abstract

Background Chronic otitis externa (OE) in dogs frequently requires anaesthetised ear flushing. Objectives To evaluate hypochlorous acid as an ear flushing and antimicrobial agent in dogs with chronic OE. Animals Twenty dogs with chronic OE caused by the same organisms bilaterally. Materials and Methods One ear was flushed under anaesthesia with hypochlorous acid, the other with saline solution. Subsequently, the ear flushed with hypochlorous acid was cleaned with the same solution twice daily for 2 weeks, the other ear with a commercial ear cleaner. An ear medication containing miconazole, polymyxin B and prednisolone was used once daily in both ears. Clinical scores were determined before the flush. Ear cytological results were obtained, a hearing test was conducted before and after the ear flush, and a culture was taken directly after flushing. Ears were evaluated after 2 weeks of therapy. Results Yeast was present in the ears of 11, cocci in one and a mixed infection in eight dogs. Five ears were negative on culture after flushing with hypochlorous acid, one after the saline flush. Clinical and cytological scores decreased significantly with both solutions after 2 weeks of treatment. There was no difference between treatments in any of the scores at any time point between treatments and in the results of the hearing test before and after the flushing procedure. Adverse effects were not seen. Conclusions and Clinical Relevance Hypochlorous acid is a suitable cleaning solution for canine OE.

Managing recurrent otitis externa in dogs: what have we learned and what can we do better?

“…Antimicrobial compounds in ear cleaners can retard microbial proliferation. Cleaners with isopropyl alcohol, parachlorometaxylenol (PCMX), chlorhexidine, hypochlorous acid and a low pH seem to be most effective [42][43][44] . TrisEDTA at 50mg/ml can show additive activity of with chlorhexidine, aminoglycosides and fluoroquinolones (see above).…”

“…A commercially available trisEDTA-NAC solution may facilitate removal and treatment of biofilms in ear canals, although time should be left between this and topical antibiotics as an in vitro study found most interactions between NAC and enrofloxacin or gentamicin were indifferent to antagonistic 49 . Other compounds with potential anti-biofilm and antimicrobial activity include chlorhexidine, polihexanide, hypochlorous acid 44,50 and trisEDTA 2 .…”