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

## TL;DR

This study found that large dogs and certain breeds are less likely to get ear infections, while brachycephalic and medium-sized dogs are more prone to them.

## Contribution

The study identifies size-dependent features and breed-specific traits as protective or risk factors for canine otitis externa.

## Key findings

- Large-sized breeds and non-brachycephalic dogs had a reduced risk of otitis externa.
- Brachycephalic breeds like Pugs and French Bulldogs were more prone to ear infections.
- Intact female dogs and Rhodesian Ridgebacks showed significantly lower risk.

## Abstract

Canine Otitis externa is one of the most common presentations in veterinary practice. Therefore, many studies have been conducted to analyze predispositions. This study took a different approach in evaluating potential protective, mostly size-dependent, features. It was found that Rhodesian Ridgebacks, intact female dogs, semi-erect pinna formation, large-sized breeds, and non-brachycephalic breeds had a decreased risk for developing Otitis externa. On the other hand, medium-sized dogs, erect pinna formation, neutered (male and female) dogs, Cocker Spaniels, Pugs, French Bulldogs, and brachycephalic breeds, in general, tend to develop Otitis more frequently. All these factors can be taken into consideration as criteria before making certain decisions regarding which dogs to choose for breeding and if a dog should be neutered or not. Furthermore, the predisposition for brachycephalic dogs adds one more health issue to their already long list.

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. p-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.