Brachycephalic Syndrome is diagnosed if the dog has stenotic nostrils, an elongated soft palate, and laryngeal saccules which are everted. These characteristics are common in all the breeds that are listed above.
A soft palate which is elongated is defined by the palate being longer than normal and the tip extends to airway passages. The air that is moved to the lungs is obstructed by this anatomical variation. Stenosis of the Nostrils, means that the nostrils are deformed and subside inwards when the dog inhales, causing difficulty in breathing via the nose. Laryngeal Saccules that are everted occur when the tissue in the air passage, found just before the vocal chords, pulls towards the windpipe, also known as the trachea, and this impedes the flow of air.
Dogs that are diagnosed with brachycephaly usually have a narrower windpipe, a collapsed larynx (cartilaginous structure in upper part of the air passage) and show signs of the larynx being paralysed.