Diaphragmatic hernia (Proceedings)

Traumatic diaphragmatic hernia

This condition is usually the result of blunt trauma especially from automobile accidents. Diaphragmatic hernia should be considered in all patients with a history of trauma. It is believed that the diaphragmatic tear is the result of a sudden increase in intra-abdominal pressure. The pressure differential is only momentary and the pressures equilibrate readily.

Clinical signs - diaphragmatic hernia

This hernial condition maybe difficult to identify because of marked or absence of conventional presenting signs. Thus the patient maybe presented with imperceptible to life threatening clinical signs. The severity of the patient's condition is dependent upon several factors, the most important of which is a reduction in tidal volume. Loss of tidal volume is the result of a decrease in intra-thoracic space due to the presence of abdominal visceral fluid or both. Other conditions that may be present are rib fractures, pneumothorax, lung contusion, and shock. A potentially more dangerous situation exists when the stomach is in the thorax and gas cannot escape causing it to become increasingly larger.

The clinical sign most frequently seen in acute diaphragmatic hernia is dyspnea. Often the dog rests in a sitting position with the elbows abducted, Physical examination reveals intestinal sounds in the thorax, muffled heart sounds and reduced lung field. The area of dullness in percussion is increased. Careful abdominal palpation may reveal the absence of abnormal position of individual organs such as stomach, liver, spleen. In a study of 116 dogs at Ohio State University, College of Veterinary Medicine, the most common organs displaced into the thorax in diaphragmatic hernia cases were in decreasing order - liver, small intestine, stomach, spleen, fluid and omentum. Other displaced organs were also reported such as pancreas, colon, gallbladder, cecum, kidney, falciform ligament and uterus.

A dog suspected of having a diaphragmatic hernia should not be elevated by the hindquarters to see if the dyspnea becomes worse. This technique can cause sudden pressure on the lungs and heart when a large tear is present and can cause overwhelming interference with ventilation and venous return.

Radiographic diagnosis

Lateral and dorsoventral radiographs often will confirm the diagnosis. The normal diaphragmatic line is usually absent in the radiographs. Gastric or intestine gas patterns and/or radiopaque organs such as liver or spleen may be visible in the thorax displacing normal thoracic viscera. It should be noted that the organs noted in the chest at the time of radiographs were not necessarily the same as those found at surgery. This is attributable to the free movement of viscera between pleural and peritoneal cavities in many patients. Diaphragmatic hernia maybe difficult to diagnose at the time of initial injury because of lack of clinical signs. The tear is subsequently reduced by cicatrization and gradually developing clinical signs, such as intermittent vomiting, anorexia, dyspnea or reduced exercise tolerance may be seen weeks, months or even years following the trauma.