Open peritoneal drainage in horses with experimentally induced peritonitis

Peritonitis was induced in 12 horses by median celiotomy and 1 hour of small intestinal ischemia. Six horses had primary closure of the incision, whereas six horses had a plastic mesh sutured to the ventral abdominal wall leaving the abdomen open for ventral drainage. The mesh was removed after 5 days and the abdominal wall was closed by apposition of the linea alba and subcutaneous tissues and approximation ef the skin edges. Peritoneal fluid was collected and analyzed for nucleated cell count and total protein concentration on days 0 and 5. Serum biochemical profiles, serum electrolyte concentrations, and complete blood counts were performed on days 0, 1, 2, 5, 6, 10, and 14. Body weight, rectal temperature, and physical examination findings were recorded daily for 30 days, then horses were euthanatized and the abdominal cavity was examined for the presence of adhesions. Histological examination was performed to assess the inflammatory response of the healing body wall; inflammation scores were significantly lower in horses that had primary closure of the incision. The mesh was well tolerated by all horses and allowed egress of peritoneal fluid for 5 days. Adhesions were present in four control horses and in two horses that had open peritoneal drainage. All horses that had open drainage developed incisional infections after mesh removal. Abdominal wall herniation did not occur in any of the horses. The mild peritonitis induced in this study was insufficient to establish the efficacy of open peritoneal drainage for an established peritonitis in horses; however, the results of this study indicate that open peritoneal drainage is feasible in horses.