Otitis externa, or inflammation of the outer ear canal, is common in dogs with canine atopic dermatitis (cAD). While much is known about skin microbiota differences between allergic and healthy dogs, the microbial environment of the ear canal has been less studied. Ngo et al. (2018) investigated whether atopic dogs without clinical otitis already show microbial alterations.
The study analyzed ear swabs from 9 healthy dogs and 11 dogs with confirmed cAD. Using 16S rDNA sequencing, researchers profiled bacterial communities over a 28-day period. They found that the ear microbiota was relatively stable across time, but differences were evident between groups.
Atopic dogs displayed clear signs of dysbiosis, with increased levels of Staphylococcus spp. and Ralstonia spp., both of which are opportunistic bacteria linked to infections. In contrast, Escherichia spp. were more abundant in the ears of healthy dogs. These shifts mirror those seen on the skin of allergic dogs and may help explain their predisposition to bacterial ear infections.
The findings suggest that microbial imbalance in the ear canal occurs even before visible signs of otitis appear. Monitoring and managing these subtle microbiota changes could help in the early prevention of bacterial otitis in allergic dogs, improving their long-term ear health and comfort.
Source: Ngo, J., Taminiau, B., Fall, P. A., Daube, G., & Fontaine, J. (2018). Ear canal microbiota – a comparison between healthy dogs and atopic dogs without clinical signs of otitis externa. Veterinary Dermatology, 29, 425–e140.
