The chest usually has "negative pressure" (or vacuum) between the lung tissue and the chest wall (ribs and muscle); any leaks in the system severely jeopardize the breathing mechanism. If this vacuum effect disappears, the body cannot draw air into the lungs. Or, if enough air, blood, or tissue leak between the lungs and the chest wall, then the lungs cannot expand to inhale enough air.
- Visualized open wound on the animal's chest or witnessed trauma.
- Animal may be in respiratory distress
First Aid: Minimize stress. Transfer your pet to a veterinary facility immediately. Respiratory distress can be fatal in a few minutes.