History: There was an acute onset of vomiting followed by dyspnea and apnea. Chest compression was applied. The dog responded. The patient is cyanotic and dyspneic. There are no audible lung sounds.
•There is a large oval-to-discoid gas collection in the left hemithorax that is bounded by a thin soft tissue rim.
•Superimposed on the gas is a homogeneous soft tissue opacity with multiple small gas pockets.
•There is marked cardiac displacement to the right and marked atelectasis of the right lung.
•In the lateral view, there is a triangular soft tissue opacity ventral to the gas collection.
•There is a small amount of gas in the cervical esophagus.
•The findings are most consistent with a left sided diaphragmatic hernia with severe gastric distention, most likely the result of outflow obstruction. This is termed tension gastrothorax.
•The distended stomach contains mostly gas but there is also a smaller amount of intraluminal fluid with small gas pockets.
•The triangular soft tissue opacity ventral to the stomach in the lateral view is consistent with the spleen.
•The gastric distension has caused a mediastinal shift and marked atelectasis.
•This is a life-threatening scenario.
Gastric decompression using trocarization or orogastric intubation is indicated, followed by a laparotomy and herniorrhaphy.
•Tension gastrothorax results from pathologic distension of a stomach that has herniated into the thoracic cavity.
•In this dog it is not clear whether the gastric herniation was pre-existing, resulted from the vomiting, or from the thoracic compression.
•Tension gastrothorax causes pronounced atelectasis and reduced venous return to the heart.1
•Clinically, tension gastrothorax will be like tension pneumothorax but there should be no radiographic confusion in differentiating these conditions. In tension pneumothorax, the expanded gas collection will have pulmonary markings and the shape of a lung, whereas in tension gastrothorax the expanded gas collection will be homogeneously radiolucent, except for superimposition of any solid or fluid gastric content.
•Also, in tension pneumothorax the diaphragm will be visibly displaced caudally while in tension gastrothorax there will likely be border effacement of the diaphragm.
•There may be an inherent diaphragmatic defect that predisposes to tension gastrothorax, based on a description of 5 cavalier King Charles spaniels.2 All of the hernias were on the left side, and at surgery there was a circular defect in the left crus of the diaphragm through which the stomach was herniated. Other organs herniated included the spleen (3/5), omentum (2/5) and intestine (1/5).
1. McCann B et al. Tension viscerothorax: an important differential for tension pneumothorax. Emerg Med J 2005;22:220-221.
2.Rossanese M et al. Congenital pleuroperitoneal hernia presenting as gastrothorax in five cavalier King Charles spaniel dogs. J Small Anin Pract 2019; 60:701-704.