EQUINE VETERINARY EDUCATION / AE / OCTOBER 2014


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If adhesions are located within the hernia sac, the hernial


sac is sharply incised with its junction with the body wall so that the site of adhesion can be visualised. Omentum can generally be ligated and dissected free. When intestine is adhered, it is bluntly separated from the hernial sac. Rarely, intestinal resection is required but the author has performed resection and anastomosis of the ileum/distal jejunum in one foal with a congenital inguinal body wall defect. Once either the omentum or intestine has been dissected free, the remainder of the hernial sac is sharply resected from the body wall. Rarely, infected umbilical structures can be adhered within the hernial sac. In these instances the affected umbilical structures are resected as previously described (Reef et al. 1989). Once the infected umbilical structures have been removed, the body wall can be closed. Once the hernial sac has been resected the next intraoperative decision is whether or not mesh will be required to repair large defects (10–15 cmin diameter). Mesh should be considered when large defects cannot be sutured primarily without excessive tension or a weakened body wall is at high risk of not holding suture material without failure (pulling out). The author would estimate that mesh is not required to close a congenital body wall defect in approximately 95% of foals. If at all possible, the author attempts to repair the body wall defect without mesh but this is not always possible (Whitfield-Cargile et al. 2011). As previously stated, the majority of congenital body wall


defects can be repaired with primary suture closure. The most important principle of body wall closure is to obtain a tension free closure. To achieve this, the author prefers to preplace simple interrupted sutures of No. 2 absorbable suture material. Each of the sutures are placed individually and then secured with haemostats. Once all of the sutures have been placed, the sutures are tensioned by traction on the haemostats and tied individually. Preplaced sutures allow for a tension free closure and, because generally the defects are small (<10 cm), it allows for easy confirmation that intestine or omentum is not trapped by the suture material. The author uses the following criteria for placement of


mesh: no evidence of infection or contamination of the surgical incision intraoperatively; inability to close the body wall without excessive tension; and weakened body wall (usually from previous surgery or trauma). Having used multiple types of prosthetic mesh, polypropylene is the preferred mesh for body wall reconstruction. It is strong, minimally reactive and easy to work with. The author prefers to double the thickness of the mesh for maximal strength. The mesh is anchored to the margin of the incision approximately 5–10mm from the edge using nonabsorbable suture material (polypropylene or braided polyester) (Tulleners and Fretz 1983). Double armed suture material is particularly useful. All of the sutures are preplaced around the margin of the incision approximately 5mm apart. If polypropylene suture is used the suture ends can be threaded through the mesh after suture placement. If polyester suture is used, the suture must be positioned through the mesh first. If possible the body wall is apposed first and the mesh is secured on the skin side of the incision (mesh overlay). If it is impossible to oppose the body wall without excessive tension then the mesh should be inserted retroperitoneal if at all possible to minimise exposure of the mesh to the abdominal viscera. If the mesh is not located retroperitoneally there is increased risk of intestinal adhesion to the mesh (Tulleners and Fretz 1983). If the body wall can be opposed but under


excessive tension or if there is a concern of suture failure, the prosthetic mesh can be overlaid on the skin side of the abdominal closure (Kummer and Stick 2012). The author has found this to be a secure closure without the risk of intestinal adhesion to the prosthetic mesh. Once the body wall defect has been closed, with either


suture material or mesh, the next step is to eliminate as much dead space as possible. Unclosed dead space frequently results in seroma formation and excessive incisional oedema. Seroma formation and oedema are not as critical an issue for suture closure of body wall defects but are of paramount importance when mesh is used. Seroma formation following mesh herniorrhaphy predisposes to incisional infection. Infection and mesh in combination can be disastrous. The end result of infected mesh herniorrhaphy is the need to remove the mesh at a later date. This results in increased cost to the owner and increased patient morbidity. The only way the author knows to eliminate dead space is


to suture multiple rows of fascial/subcutaneous tissue closure. This can include inclusion of the body wall fascia in the closure. If dead space cannot be eliminated, seroma formation is inevitable. Tacking of the subcutaneous tissue to the fascial layers is also indicated. Skin closure is complicated by excessive skin left behind following reduction of the hernia and resection of the hernial sac. Some of the excessive skin is removed when the original elliptical incision is made around the hernia at the beginning of the procedure, but frequently excess skin is still left behind following closure of the fascial and subcutaneous tissue layers. This will result in a ‘dog ear’ at the ends of the incision. This is prevented by sharp excision of the remaining excessive skin with a scalpel blade, accomplished by clamping of the excess skin with Allis tissue forceps to oppose the skin edges and then the skin is sharply excised with a scalpel blade. The author prefers the placement of absorbable suture material in the skin so that suture or staple removal is not required. Foals have been known to injure themselves during the restraint necessary to remove either skin staples or nonabsorbable suture material. Following recovery from anaesthesia if a mesh


herniorrhaphy or large hernial defect is closed bandaging is recommended to minimise the risk for incisional seroma formation. However, it is challenging to maintain abdominal bandages in males because they frequently urinate on the bandage. Caudal flank or inguinal hernias can be bandaged but are difficult to maintain because of their location. Nonetheless, if a bandage can be placed, it should be, as it does help prevent seroma formation and excessive oedema formation. The most common complications following surgical repair


of congenital body wall defects include incisional infection, seroma formation and reherniation. Incisional infection without mesh is managed with suture removal, to facilitate drainage, and antimicrobial therapy. Incisional infection will resolve once the suture material used for closure has absorbed. Incisional infection in combination with prosthetic mesh is a different matter as infection of the mesh can typically not be resolved without removal of the mesh. If mesh removal is required to resolve the signs of infection then timing of mesh removal is important. The mesh needs to remain in place long enough to allow enough fibrosis to form so that reherniation does not develop; typically this takes 2–3 months. The other complicating factor is that mesh removal following incisional infection is very challenging and could result in reherniation if


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