Conventional therapies for oxygen supply used in the veterinary clinic may be inefficient when offering a satisfactory recovery to post-surgical patients under chest surgical procedures with hypoxemic respiratory failure, demanding strategies to improve oxygenation indicators. The present work describes the use of high-flow nasal cannulas in two patients submitted to chest surgeries and under general anesthesia. Patient #1 was submitted to a subphrenic pericardiectomy by thoracoscopy, and patient #2 was submitted to a percutaneous rib fracture reduction by a chest tube. Both patients were recovered with a high-flow oxygen therapy in the post-surgical phase at flow rates of 600 and 1,071 mL/kg/minute, respectively. The oxygen was delivered using a commercial device of active humidification, non-condensable suction with heating system and bilateral nasal cannula, offering an air temperature of 37 ºC, humidity of 98% and inspired fraction of oxygen of 50%. A percutaneous gasometry was performed (dorsal metatarsal artery) after 15 minutes of extubating of the patient, and a second arterial sample was collected 60 minutes after the installation of the high-flow device. An increase in the partial pressure of oxygen (PaO2) was observed without an increase in the partial pressure of carbon dioxide (PaCO2). Additionally, both patients reported satisfactory tolerance to the device. High-flow nasal cannulas should be considered within non-invasive ventilatory support strategies during post-extubating in patients submitted to chest surgeries.