While the flat face and short snout of brachycephalic dog breeds, such as the bulldog, pug, shih tzu and chow chow, lend those dogs a certain quirky charm, that aesthetic peculiarity comes at a price. Brachycephalic airway syndrome is the term given to the wide variety of respiratory health problems that are linked to this trait in dogs.
One of the defining physical characteristics of brachycephalic breeds is their narrow nostrils. This in and of itself makes efficient breathing difficult, but the extra effort required by the dog to take in sufficient air puts a lot of strain on the nose, causing him to wheeze. Stenotic nares can lead to other respiratory problems, due to the excess strain on the respiratory system.
Elongate Soft Palate
Due to the unusual physiology of your dog's face, his soft palate may be elongated. This is because the mouth of brachycephalic breeds are typically quite small, but their teeth, tongue and palate are of a relatively large size. The consequences of this is that the soft palate extends beyond the roof of the mouth and can block the airway.
Excess Pharyngeal Tissue
Due to the small, compressed nature of the mouth and throat, some of the pharyngeal tissue is redundant. It folds and forms a concertina shape in the throat, potentially making breathing difficult for the dog.
Everted Laryngeal Saccules
The laryngeal saccules are the small structures located on either side of the larynx, in between the vocal chord folds. When these become everted, due to the condensed size of the respiratory system, they can protrude into the laryngeal opening. This causes the snorting, wheezing and coughing that is characteristic of brachycephalic breeds
Tracheal and Laryngeal Deformity
The trachea, or windpipe, is made up of rings of cartilage. These rings hold the trachea open, allowing air to pass freely into the respiratory system. However, in brachycephalic breeds, these rings may be thicker than usual, causing the space between them to be more narrow than they should. This often results in narrowed airways and breathing problems. Brachycephalic breeds are prone to laryngeal collapse, where the laryngeal wall involuntarily collapses, causing obstructed breathing.
Brachycephalic breeds are prone to heat stroke. This is because they are unable to effectively take in the air required for thermoregulation. When a flat-faced breed becomes hot, they simply can't cool off in the same way as other breeds. They may pant heavily, but their respiratory anatomy hampers the effectiveness of doing so. For this reason, owners of brachycephalic breeds typically avoid exposing their pets to heat stress.
By Simon Foden
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About the Author
Simon Foden has been a freelance writer and editor since 1999. He began his writing career after graduating with a Bachelors of Arts degree in music from Salford University. He has contributed to and written for various magazines including "K9 Magazine" and "Pet Friendly Magazine." He has also written for Dogmagazine.net.