Development of a critical-sized ventral hernia model in the pig

Background: The pig is commonly used as a preclinical model for ventral hernia repair. However, no study has verified that an unrepaired surgically induced hernia (control) in the pig does not heal spontaneously but rather develops a persistent hernia. Without such verification in any given model, one cannot draw conclusions on the efficacy of the repair technique investigated.

Materials and methods: Three surgically induced hernia models with increasing severity were created in eight pigs. These included 10-cm retrorectus partial-thickness (model 1) and 15-cm preperitoneal full-thickness (model 2) incisional defects and an 8 × 8 cm preperitoneal full-thickness excisional defect (model 3). Postoperative management included use of an abdominal binder, and in some cases, suction drainage, for 2 wk to support the repair and prevent seroma. Models were evaluated for persistence of hernia at 5 wk using clinical and radiographic assessments.

Results: All pigs developed clinical hernias after 2 wk of defect creation, but only models 1 and 3 had clinically persistent hernias at 5 wk. At 5 wk, the average defect area was 97 cm² in model 1, 66 cm² in model 2, and 245 cm² in model 3. Dense fibrotic scarring was observed in the models with resolved hernias.

Conclusions: Our results highlight the need to verify an unrepaired hernia injury model does not heal spontaneously prior to using it for hernia repair studies. The partial-thickness incisional model 1 and full-thickness excisional model 3 formed persistent hernias in pigs at 5 wk and should be further explored as models for investigating hernia repair strategies.