Use of a nitinol stent to palliate a colorectal neoplastic obstruction in a dog.

Case Description: A 12-year-old castrated male Labrador Retriever was evaluated for clinical signs associated with colorectal obstruction.
Clinical Findings: The dog had a 2-week history of tenesmus and hematochezia. On rectal examination, an annular colorectal mass was palpable extending orad into the pelvic canal. The original diagnosis of the colorectal mass was a mucosal adenoma. The dog was maintained on a low-residue diet and fecal softeners for a period of 13 months after initial diagnosis. At that time, medical management was no longer effective.
Treatment and Outcome: Placement of a colonic stent was chosen to palliate the clinical signs associated with colorectal obstruction. By use of fluoroscopic and colonoscopic guidance, a nitinol stent was placed intraluminally to open the obstructed region. Placement of the stent resulted in improvement of clinical signs, although tenesmus and obstipation occurred periodically after stent placement. At 212 days after stent placement, the patient had extensive improvement in clinical signs with minimal complications; however, clinical signs became severe at 238 days after stent placement, and the dog was euthanized. Histologic evaluation of the rectal tumor from samples obtained during necropsy revealed that the tumor had undergone malignant transformation to a carcinoma in situ.
Clinical Relevance: A stent was successfully placed in the colon and rectum to relieve obstruction associated with a tumor originally diagnosed as a benign neoplasm. Placement of colorectal stents may be an option for the palliation of colorectal obstruction secondary to neoplastic disease; however, clinical signs may persist, and continuation of medical management may be necessary.