Small Intestine
Diaphragmatic Hernia
Basic Information 
Definition
• Herniation of small intestine into the thoracic cavity through a defect in the diaphragm.
• May be congenital in origin or acquired.
• Acquired diaphragmatic hernias are seen in foals secondary to rib fractures (ribs 3–8) sustained during parturition.
• The most common cause of acquired diaphragmatic hernias in the adult horse is trauma.
• Herniation through the diaphragm can also include the stomach, ascending colon, liver, and spleen.
Clinical Presentation
Physical Exam Findings
Etiology and Pathophysiology
• Congenital: Incomplete formation of the diaphragm. Small congenital defects are usually found in the abaxial dorsal portion of the diaphragm.
• Acquired: Associated with increased abdominal pressure during parturition or a traumatic incident.
• Herniation through small defects causes strangulation and ischemic necrosis of the affected small intestine. Herniation through large defects may cause partial obstruction and respiratory distress because of an inability to expand the lungs normally.
Diagnosis 
Initial Database
• Rectal examination may or may not reveal abnormalities. May palpate distended small intestine.
• Nasogastric reflux (NGR) is seen as the disease progresses. NGR may be variable based on the size of the defect and the degree of obstruction.
• Abdominocentesis may or may not be abnormal and may significantly underestimate the degree of intestinal injury. With small defects, the affected segment of small intestine becomes sequestered within the thoracic cavity, causing confusion in interpretation of the results of abdominocentesis.
• Complete blood count and chemistry profile are normal early in the disease process. As the colic progresses, changes consistent with dehydration and endotoxemia occur rapidly. A mild metabolic acidosis may also be present.
• Blood gas analysis may indicate respiratory compromise and hypoxemia.
• If the suspicion of diaphragmatic hernia is high based on the history and physical examination findings, thoracocentesis may be performed. This procedure should be done with caution because puncture of the intestine is a risk.
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