Brachycephaly, Ear Anatomy, and Co—Does Size Matter? A Retrospective Study on the Influence of Size-Dependent Features Regarding Canine Otitis Externa

This study, which involved 868 patients, focused on size-dependent features (body size, pinna formation, brachycephaly, overweight) and their associations with the occurrence of canine Otitis externa. Breed, sex, and neuter status were also included. Canine patients diagnosed with Otitis externa presented between 1 January 2019 and 31 July 2022 in a referral small animal hospital were included, while dogs with matching categories presented at the Unit for Reproductive Medicine in the same time period functioned as a randomized control group. Statistical analyses included Pearson-Chi² test, Fisher's exact test, and Bonferroni correction. <i>p</i>-values of <0.05 were considered statistically significant. Rhodesian Ridgebacks, non-brachycephalic breeds, intact female dogs, dogs with semi-erect ears, and large-sized breeds had a significantly reduced risk of developing Otitis externa. Conversely, Pugs, French Bulldogs, Cocker Spaniels, medium-sized breeds, dogs with erect ears, brachycephalic breeds, neutered female, and neutered male patients were more frequently diagnosed with Otitis externa. The study concluded that large breed dogs showed a reduced risk of developing Otitis externa in our data set as well as meso- and doliocephalic breeds and dogs with semi-erect pinna formation. Particularly, the Rhodesian Ridgeback and intact female dogs showed a significantly low risk of suffering from Otitis in the current study.