34th Annual Scientific Meeting proceedings

Objectives:

Brachycephalic Obstructive Airway Syndrome (BOAS) involves partial obstruction of the upper airways due to conformational changes. Similar to obstructive sleep apnea syndrome in humans, intermittent hypoxia leads to various systemic consequences, such as impaired oxygenation and alveolar microinjuries, which can trigger interstitial lung disease and pulmonary fibrosis. This study aimed to assess the effects of BOAS on the respiratory system in affected dogs.

Methods:

A prospective observational study was conducted, including fifty-two brachycephalic dogs clinically classified by BOAS grades using validated exercise tests, along with fifteen beagles serving as mesocephalic controls. Arterial blood gas analysis, pulmonary B-mode ultrasonography, and Acoustic Radiation Force Impulse (ARFI) elastography of the pleuropulmonary surface were performed. Statistical significance was set at p<0.05.

Results:

Dogs clinically affected by BOAS exhibited elevated values of partial pressure of carbon dioxide (p=0.017), base excess (p=0.04), and bicarbonate (p=0.019). Additionally, they showed increased thickness of the pleuropulmonary line (PPL), measuring 0.8 mm (IQR 0.18 mm), compared to 0.7 mm (IQR 0.1 mm) in mesocephalic dogs (p=0.003). A positive correlation was observed between BOAS severity grades and increased PPL thickness (p=0.003). In ARFI elastography, PPL stiffness was higher in the control group at 4.02 m/s (IQR 0.72) compared to 3.76 m/s (IQR 1.19) in BOAS-affected dogs (p=0.023).

Conclusions:

Dogs clinically affected by BOAS showed changes in oxygenation levels and increased PPL thickness, suggesting the presence of underlying lung disease. This study highlights the severe respiratory consequences of BOAS in brachycephalic dogs.

Financial Support: São Paulo Research Foundation 2023/12747-5