This includes PTX (open, closed, tension), hemothorax (HTX), and diaphragmatic hernia. A restrictive breathing pattern is the classic presentation—shallow, rapid respiration with muffled lung and/or heart sounds. Auscult the chest for decreased lung sounds over most of the thorax, which suggests either fluid (blood) or air in the pleural space, pulmonary contusions, or diaphragmatic hernia.

- Open PTX requires immediate action. Rapidly clip hair from around the wound, and apply any occlusive seal over the wound. Apply a chest bandage to secure the material. Delay wound closure until the MWD is stable. Open PTX always requires chest decompression after closure of the wound.
- The presence of decreased lung sounds in a trauma patient with signs of respiratory distress, or rapid clinical deterioration in a MWD with respiratory distress is sufficient justification for needle thoracocentesis.
- Thoracocentesis is readily and rapidly accomplished, and safe when performed properly – “When in doubt, tap it!” Figure 29 on the next page shows the location for needle thoracocentesis in dogs.13 See Table 8 for thoracocentesis technique in MWDs.
- The mediastinum in dogs is thin and typically ruptures; therefore, always tap both sides of the chest, even if a positive tap is achieved on one side of the chest, as air will form pockets and will migrate.
- Repeated thoracocentesis may be required to stabilize the patient. A negative chest tap doesn't always mean there's not an abnormal accumulation of air or fluid in the pleural space – it may mean you just couldn‘t find it! “When in doubt, tap it again!”
- In dogs, the intercostal artery, vein, and nerve run on the caudal aspect of each rib; thus, the best approach is by inserting the needle or catheter in the center of the intercostal space or at the cranial aspect of a rib.

Figure 29. Location for Needle Thoracocentesis.

Figure 29 shows anatomic location for needle thoracocentesis in dogs, with the dog in lateral or sternal recumbency, and the needle inserted generally on the mid-lateral thorax between the 6th to 8th intercostal space. Count forward from the last rib (#13; red dotted line) to find the insertion site.