Surgical repair of a diaphragmatic hernia in a racehorse.

: A 9-year-old Thoroughbred was evaluated for clinical signs of acute abdominal pain. During laparotomy, a rent in the diaphragm and herniation of the small intestine into the thoracic cavity were detected. Because edges of the rent were smooth and fibrous, which suggested the defect was chronic, the abdomen was closed without repairing the rent. After recurrence of clinical signs, a second laparotomy was performed, during which the intestines were found to have reherniated. The diaphragmatic rent was repaired, using a polypropylene mesh secured with stainless steel staples. The horse recovered and subsequently returned to racing and jumping. A diaphragmatic hernia should be suspected in horses that have moderate to severe signs of abdominal pain for which a definitive cause can not be identified. Thoracic ultrasonography or radiography can be used to confirm the hernia. Diaphragmatic hernias in horses can be successfully repaired using mesh implants secured with staples.