Abstract
CASE SUMMARY: Cranial ventral midline hernias, most often congenital, can be associated with other congenital abnormalities, such as sternal, diaphragmatic or cardiac malformations. A 4-year-old multiparous queen with a substernal hernia was admitted for evaluation of a mammary mass. During CT examination, a bifid sternum, the abdominal hernia containing the intestines, spleen, omentum, three fetuses, a mammary mass and an incidental peritoneopericardial diaphragmatic hernia were identified. Surgery consisted of a standard ovariohysterectomy and repair of the peritoneopericardial hernia. Primary closure of the abdominal hernia was attempted but deemed impossible even after the ovariohysterectomy, splenectomy and a partial omentectomy. An external abdominal oblique muscle flap was used to close with no tension on the cranial part of the hernia. One month postoperatively, the queen had no respiratory abnormalities and the herniorrhaphy was fully healed. RELEVANCE AND NOVEL INFORMATION: This case is the first description of a 4-year-old multiparous pregnant queen with complex congenital malformations and surgical correction of a peritoneopericardial hernia and a 6 × 8 cmsubsternal hernia with an external abdominal oblique muscle flap. Life-threatening sequelae associated with large abdominal hernias can be attributed to space-occupying effects known as loss of domain and compartment syndrome, which is why a muscle flap was used in this case. The sternal cleft was not repaired because of the size of the cleft and the age of the cat.