Single Cold Atmospheric Plasma Therapy May Improve the Treatment Outcome of Canine Otitis Externa With Secondary Infection.

Background: Otitis externa (OE) with secondary bacterial or yeast infection is a common problem in small animal practice. Cold physical plasma (CPP) has been reported to have antimicrobial activity in vitro.

Hypothesis/objectives: This randomised, blinded, prospective study assessed the influence of additional CPP treatment on the recovery of canine OE with secondary infection.

Animals: Twenty-one dogs with bilateral clinical OE and cytological evidence of infection were included.

Materials and methods: An ear flush was performed with saline solution in all dogs. Additionally, one ear of each dog, chosen in a prospective randomised fashion, was treated with CPP for 30 s. Afterwards, both ears were treated with a depot ear medication containing betamethasone, terbinafine and florfenicol. Seven days later, the depot medication was administered again as recommended by the manufacturer. On Day (D) 0, D7 and D21, a clinical otic score and a validated semiquantitative cytological score were compared with a Friedman test and Dunn's multiple comparison test.

Results: Ears treated additionally with CPP showed lower otic scores after 21 days compared to nontreated ears, although this difference was not significant (p = 0.08). Cytological scores improved over 21 days with cocci in CPP-treated (p = 0.003) and nontreated ears (p = 0.02). With yeast, there was significant improvement in CPP-treated (p = 0.0002) ears in contrast to nontreated ears. With rods, the improvement was not statistically significant in either group.

Conclusions and clinical relevance: CPP treatment seems to be a promising option as an additional treatment after ear flushing.