BRACHYCEPHALIC OBSTRUCTIVE AIRWAY SYNDROME

Brachycephalic obstructive airway syndrome (BOAS) refers to an obstructive airway condition that commonly affects short-faced breeds, including the British Bulldog, French Bulldog, Pug, Boston Terrier and other bulldog breeds and crosses. These breeds have been bred with relatively short skulls, muzzles and noses, and because of this, their airways can sometimes be compressed, which can present as noisy breathing and poor exercise tolerance.

Affected brachycephalic dogs must increase their effort to breathe to overcome the resistance generated by the upper airway obstruction. A proportion of brachycephalic dogs suffer BOAS, but not all dogs of a given breed are equally affected.

Some dogs will also vomit or gag when swallowing, or have repeated episodes of regurgitation. Episodes of fainting and collapse can occur at times of excitement or stress in some severely affected dogs. Others may overheat, sometimes fatally. Being overweight tends to worsen the problem.

If left uncorrected, the condition usually worsens with age and can lead to significant secondary changes, and premature death.

The anatomical airway problems we see from brachycephaly can include:

1. Stenotic nares – where the nostrils and the nasal vestibule are too small to allow adequate passage of air making breathing through the nose difficult.

2. Elongated and/or thickened soft palate – where the soft palate is too long and/or too thick. In these cases the soft palate is excessively long allowing it to sit within the opening of the trachea (windpipe) and thus obstructs normal airflow. The elongated soft palate creates turbulent airflow resulting in the increased respiratory noise we hear in some brachycephalic dogs, including snoring.

3. Everted or swollen laryngeal saccules – These saccules normally sit either side of the floor of the larynx just in front of the vocal folds / chords. In some brachycephalic dogs, the increased effort of breathing may result in the saccules becoming swollen resulting in obstruction of airflow. Swollen laryngeal saccules is the first stage of collapse of the larynx – a very serious condition.

4. Tonsillar hyperplasia or enlarged tonsils. This is common in brachycephalic breeds due to chronic inflammation.

5. Overgrowth of the nasal turbinates

6. Tracheal hypoplasia – where the trachea (windpipe) is too small.

7. Enlarged tongue – The tongue can be particularly large which contributes to airway obstruction.