A 0.15% chlorhexidine and Tris–EDTA ear-flushing solution in the therapy of bacterial otitis

The aim of this randomized and blinded study was to evaluate the efficacy of an ear-flushing solution containing 0.15% chlorhexidine and Tris–EDTA as sole treatment of canine ears with bacterial overgrowth (+/) Malassezia), or purulent otitis. After an ear flushing performed by the investigator, the subsequent flushings were performed daily at home. Clinical signs (pruritus/pain, erythema, oedema, quantity and odour of the discharge) were evalueated on days 0, 14 and 28, on a 0–4 point scale. Bacteria and neutrophil semiquantitative counts (0–4 scale) on cytology were performed at each time point from each ear. Within-group comparison of the baseline characteristics (age, weight and clinical parameters) was performed using a Friedman analysis of variance (ANOVA). Between-group comparison of the reduction of clinical and cytological parameters was performed using Student’s paired t-test; P < 0.05 was considered statistically significant. Fifty-nine ears, 34 treated with the commercial solution and 25 with the vehicle, of 33 dogs were included in the study. There was no significant difference between groups in age, weight, clinical or cytological parameters on day 0. Improvement in the active ingredient group was always greater than the vehicle group. On days 14 and 28, in the active treatment group there was a significant improvement of all parameters, while in the vehicle group improvement of oedema and bacteria was not significant. In conclusion, this study suggests that the commercial solution was able to significantly reduce clinical signs and cytological parameters in bacterial otitis, when used daily for 14–28 days.