EXPRESS: A case of a complex tubular enteric duplication in an elderly cat

Case summary: Feline enteric duplication is a rare congenital anomaly with only few reports describing the diagnostic imaging features. An 11-year-old female spayed domestic shorthair cat presented for repeated bouts of tenesmus, constipation and urinary tract infections as well as weight loss and intermittent vomiting. Abdominal radiographs documented a tubular soft tissue structure in the caudal abdomen, ventral to the feces-filled colon. Initially, this structure was wrongly presumed to represent an enlarged uterus given its location, although the cat was spayed. An intraoperative ultrasound demonstrated an intestinal bifurcation of the distal ileum with a duplicated cecum and colon. The ileums appeared separated with discrete circumferential wall layering and entered at separate ileocecocolic junctions (ICJ). The duplicated colon appeared as a large tubular structure with circumferential wall layers and was connected to the primary colon by an outer echogenic membrane that aligned with the serosal layer. A shared lumen was suspected distally. The histopathologic diagnosis was a congenital ileal branch with colonic duplication as well as neutrophilic and lymphoplasmacytic ulcerative colitis. Relevance and novel information: This case illustrates the radiographic and ultrasonographic features of a colonic duplication involving the distal ileum and colon in an elderly cat.