Type Ib (tubular) non-communicating colonic and rectal duplication in a cat

A six-year-old, 4.14-kg, female spayed domestic shorthair cat was referred for vomiting, obstipation, tenesmus and stranguria for five days. On abdominal radiographs, a soft tissue mass effect was visible at the pelvic inlet. During abdominal ultrasound, a tube-like structure filled with hyperechogenic fluid was identified dorsal to the urinary bladder displacing the colon. A presumptive diagnosis of pyometra was made. Exploratory laparotomy revealed the presence of a tubular antimesenteric colonic and rectal mass causing almost complete compression of the urethra, descending colon and rectum. The mass was surgically resected. Histology confirmed a colonic duplication. There was no recurrence of clinical signs for six months. This report emphasises that colonic duplication is a possible differential diagnosis for prepelvic and intrapelvic masses in feline patients. Surgical excision of the duplication is a viable treatment option, alleviating clinical signs and offering good long-term outcome.