Brachycephalic syndrome (BS) constitutes a major health & welfare problem in several short-nosed breeds as it causes breathing difficulties, heat & exercise intolerance, sleep-disordered breathing, cyanosis & collapse in the affected individuals. In line with the increased popularity of brachycephalic breeds & the demand for hyper-types, the problem seems to be continuously growing. Surgery & medical management can alleviate the symptoms of BS at the individual level, but prophylaxis through breeding is the only available solution at population level. As such, there is an urgent need for breeding efforts to improve the health status of dog breeds affected by BS.

Although the degree of external Nasal Stenosis is not a direct expression of the degree of intranasal stenosis, the inner nasal vestibule is often concomitantly reduced due to a relatively large inner wing of nasal cartilage. While moderate-to-severe stenotic nostrils have been found to increase the mean BS index by only 16% across brachycephalic breeds, it has been shown that the risk of BS is increased by about 20 times in French bulldogs with moderate-to-severely stenotic nares

Our study unambiguously shows that the NS score has a large impact on the functional ability of French bulldogs. This single parameter results in an additional 10.59 and 8.45 score points in dogs with open or mildly stenotic nares, respectively. It follows that dogs with open nares are more likely to lead a healthier life compared to dogs with stenotic nares. Hence, selecting only dogs with open nares for breeding would seem to be an obvious means to improve functional ability and, in turn, health & welfare at the population level, & would in fact comply with the FCI standard for the breed, which states that the nose should ‘allow normal nasal breathing’

Nevertheless, since this would exclude 81% of the population from breeding, this is obviously not a prudent solution. The average level of genetic diversity in the French bulldog population is comparable to many other pure dog breeds, implying that selection should be performed cautiously while also taking other health aspects into consideration