Pneumothorax

Pneumothorax is the presence of air in the space between the pleural membranes, the two membranes that cover the lungs and line the chest cavity. Pneumothorax occurs when the air leaks into the space from inside a lung. The air can increase pressure on the lung, resulting in a collapsed lung (tension pneumothorax). This condition may result from a rupture of lung causing blister-like lesions or trauma to the trachea which is usually a result of bite wound from a confrontation with another dog or cat, foreign body or tumor. These are rather uncommon causes. In most cases pneumothorax follows a motor vehicle accident and the air is presumed to come from a small tear in the lung. The lung tears tend to seal after the lung collapses.

If the trachea is punctured, air and/or bacteria can leak into the surrounding tracheal tissues and cause air bubbles form in the chest. In case of bacterial leak, the condition may be fatal.

Signs of Pneumothorax

Dogs with pneumothorax have rapid, shallow breathing, and difficulty inhaling. This condition should be considered as an emergency that requires immediate veterinary attention. Blood tests can reveal a lack of adequate oxygen supply. A chest X-ray can reveal a collapsed lung and the presence of air outside the lung. For identifying the underlying cause of lesions computed tomography is used.

If a small amount of air leaked into the chest cavity, it can be quickly removed with a needle or syringe. Animals with moderate pneumothorax will usually recover after 4-5 days of cage rest. More persistent air leaks may require that a tube be temporarily planted within the chest cavity for drainage until leakage of air is stopped. If the problem can be solved in this way, the leak must be closed surgically (rare).

The occurrence of spontaneous pneumothorax in some bloodlines raises the possibility of autosomal recessive inheritance of this disorder.

References:
1. UC Davis Book of Dogs: The Complete Medical Reference Guide for Dogs
2. Textbook of Small Animal Medicine By John K. Dunn

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