Sixteen dogs with otitis externa from bacterial or yeast infections were enrolled in a study to evaluate the efficacy of an ear cleanser for treatment of the infections. The solution is a commercially available product (Epi-Otic, Virbac, Fort Worth, TX) containing 2.5% lactic acid and 0.1% salicylic acid in free and encapsulated forms; chitosanide in encapsulated forms; and propylene glycol, sodium docusate, and parachlorometaxylenol (PCMX) in free form. The owners treated the ears twice a day for 2 weeks. They filled the ear canal with the cleanser and massaged the ear for 1 minute. The dogs were allowed to shake their heads, and the owners then wiped away any excess cleanser. No other treatments were allowed during the study period.

Ears were evaluated by the investigators and graded for the degree of erythema, stenosis of the vertical and horizontal ear canals, and exudation. Cytologic identification of yeast and bacteria was made, and swabs from the ears were cultured. The owners' perceptions of clinical signs, ease of treatment, odor, and the dog's reaction were also assessed. Within 2 weeks 67.7% of the ears were free of infection. All but one owner reported clinical improvement within 1 to 5 days of beginning treatment. Infections due to Staphylococcus intermedius, Pseudomonas aeruginosa, or yeast resolved in 83.3%, 100%, and 72.7% of the ears, respectively. Ten of the 31 ears remained infected at the end of the 2-week period. Two of the owners admitted to having problems treating the ears, which may have contributed to persistent, relapsing, or new infections in these dogs.

This study was funded by Virbac, Fort Worth, TX .

COMMENTARY: Otitis externa is the most commonly diagnosed disease of the ear canal in dogs. It often becomes a chronic problem, and becomes increasingly difficult to treat. This ear cleanser was effective in improving clinical signs and in some cases curing the infection. It should be considered a viable treatment option for dogs with otitis externa.

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs. Cole LK, Kwochka KW, Kowlaski JJ, Hillier A, Hoshaw-Woodard SL. VET THER 4:12-23, 2003.
4:12-23, 2003.