Esophageal strictures are frustrating to treat and manage for both owners and veterinarians. Patients classically present with signs of regurgitation. Strictures in the esophagus can be secondary to reflex esophagitis (commonly post-anesthesia), caustic substance ingestion, medications sitting on the esophageal mucosa for lengths of time (i.e. doxycycline tablets in cats), from esophageal foreign bodies, esophageal tumors, etc. Many alternative therapies have been tried because recurrence is very common. Balloon dilation procedures using endoscopic guidance is currently the treatment of choice in veterinary medicine. Regardless of the intervention chosen, many of these strictures recur and present as a monetary and clinical dilemma for our feline and canine patients. In human medicine fluoroscopy, in conjunction with endoscopy, is used for dilation of esophageal strictures, allowing better visualization that the waist of the stricture is not just stretched, but completely broken. With a similar theory to the NPS cases, esophageal strictures would ideally be balloon dilated with a stent left in place to keep the scar tissue open for the time it would take the tissue to reform. The biggest concern about doing this in the esophagus is that this area is very mobile (vs the nasopharynx) and food will need to pass through the area. The risk of the stent migrating into the stomach, or proliferative tissue growth around the ends of the stent material, makes permanent stenting for benign disease less than ideal. In order to circumvent these concerns pliable stents with a shape that would ideally hold up again peristalsis (dumb-bell and self expanding) have been tried. Knowing that the stenotic tissue will heal over 14 or more days, having a stent that can be removed or resorbed (polylactic acid or PDS stents) in a few months is being investigated. This has been studied in humans for some time and we too have now been intently investigating this option.
Case Example: “P’nut” is a 5 year old male Ferret that had a benign stricture (scar tissue) in his esophagus which developed after he was put under anesthesia for a foreign body that he ate which needed to be removed from his stomach. After 2 balloon dilation procedures it was elected to place a stent to keep this scar tissue open long-term, as the cost and stress of mutiple procedures was excessive for both “P’nut” and his family. “P’nut” is now out over 3 years and he is eating regular food without any concerns or problems.
Esophageal stenting for benign stricture in a ferret. (A) Double contrast esophagram through marker catheter in esophagus in order to determine esophageal diameter and stricture (white arrow) length. (B) Partial deployment of mesh nitinol stent (black arrows) beyond stricture. (C) Radiograph following complete deployment of stent across esophageal stricture. Notice incomplete stent expansion across stricture (black arrow). (D) Radiograph one day post-stent placement demonstrating complete expansion of stent across stricture (white arrows).
Enteral (feeding into the GI tract) methods of feeding are preferred over parenteral (intravenous) nutrition in humans due to the benefits on intestinal health of and risk of infections. Jejunal feeding in dog and cat patients is controversial. In animals that are intolerant of stomach feedings, have intractable vomiting, have pancreatitis where pancreatic exocrine duct by-pass is desired, or are unconscious and regurgitation or reflux is a concern (ventiled animals), feeding directly into the jejunum is recommended. Classically this has been done via surgical or laparoscopic technique with a high complication and orad dislodement rates. Due to the ease of placing a nasal feeding tube or an esophagostomy feeding tube, tubes have been able to be placed into the jejunum from the nares (NJ) or esophagus (EJ) with fluoroscopy +/- endoscopy, eliminating the complications associated with septic peritonitis or unnecessary gastric or jejunal orificies. NJ and EJ tube placement is aided with fluoroscopy visualizing the guidewire and catether placement into the duodenum and into the jejunum. If an upper GI endoscopic procedure is being performed at the same time (see pictures in presentation) than wire placement across the pylorus can be done through the endoscope. This technique is fast, effective and fairly inexpensive when compared to surgical placement and parenteral access and intensive care monitoring of TPN.
Colonic obstructions are rare in small animal patients. They can be due to cancerous lesions, scar tissue, or inflammatory lesions. In humans, colonic stents have been available for over a decade and are most commonly placed for people with neoplasia who are a prohibitive surgical risk or resection holds little chance of surgical cure. They have been used as a mechanism to help deobstipate for bowel preparation prior to surgery.
In humans, colonic stents can either be placed through the endoscope for direct visualization while they are deployed, or they can be placed over a guidewire with fluoroscopy alone. They are preferred to be placed through the scope for precise stricture localization, for proximal tumor locations and to guide the stent across acute angulations in the colon. In humans clinical success is seen in up to 95% of patients. These doctors have placed 4 colonic stents in cats to date; 3 for tumors and 1 for a stricture. In these cases colonoscopy was done to visualize the obstruction and help localize the lesion fluoroscopically. A guidewire was then advanced through the stenotic lesion. Under fluoroscopic guidance a self-expanding metallic stent (SEMS) was placed across the obstruction and the stent was deployed. Patency was re-established immediately in all cases and subsequent de-obstipation was achieved. All cats were fecally continent, and no stent migrations were seen.
This image is “Ivy” a 3 year old female spayed cat who was diagnosed with a benign stricture in her colon, which resulted in severe constipation, unable to pass feces for weeks. Because her scar tissue was in the part of her colon that was inside her pelvis the surgery was declined by the owner to resect this tissue and it was elected to place a stent to keep her colon open. Two years later “Ivy” is reported to be continent and is healthy, defecating without any trouble.