Biliary Peritonitis Secondary to Proximal Duodenal Perforation in a Cat

A 10-year-old spayed female Korean shorthair cat was presented with hematemesis and lethargy. Marked volume of free peritoneal gas was identified on abdominal radiographs. Bile pigment was identified in peritoneal fluid obtained by abdominocentesis, consistent with biliary peritonitis. Ultrasound examination was limited by pneumoperitoneum and severe peritonitis, making it difficult to differentiate gastrointestinal perforation from biliary system rupture. Two defects in the proximal duodenum near the major duodenal papilla (MDP) were identified with a non-anesthetic computed tomography (CT) scan. Exploratory laparotomy confirmed two perforations and revealed severe biliary peritonitis. Despite surgical repair and intensive treatment, the cat died 3 days later. This case highlights the importance of considering duodenal perforation near the MDP as a differential diagnosis when pneumoperitoneum and biliary peritonitis are present.