Emil Ofner DVM, Veterinary Clinic More
Authors : Emil Ofner, DVM
Davor Crnogaća, DVM
Ivica Ukić, DVM
Silvijo Tarasić, Eng; OLYMPUS d.o.o. Zagreb
Small Animal Veterinary Clinic More, Šibenik, Croatia
Key words : esophageal stricture, balloon dilatation, regurgitation
Many diseases can cause esophageal stricture formation. Strictures in dogs are most frequently caused by foreign objects trapped in esophagus. The easiest way to diagnose and treat esophageal strictures is with flexible gastroscopes. Although there are lots of ways to dilate stricture, through the scope method, using esophageal balloon catheter is simple and safe method enabling direct visualisation of whole procedure.
Post-traumatic esophageal strictures in small animals are relatively rare problems. Most common cause of post – traumatic esophageal strictures is foreign body entrapment in the esophagus. Also, post – traumatic endoluminal strictures can be caused by caustic material ingestion or as a complication of esophageal surgery. In all of these situations damage of esophageal wall layers causes local inflammation with production of fibrous connective tissue. Local fibrosis or scar formation causes reduction of esophageal diameter thus causing stricture. Common symptoms of esophageal strictures are : regurgitation, salivation, dysphagia and ptyalism. Treatment is usually dilatation with balloon catheters or different types of cylindrical tubes called bogies (Table 1).
Case presentation :
Female, 9 years old West Highland White Terrier was brought to our clinic because of chronic regurgitation that lasted for four weeks. Prior to this, dog ingested bones and vomited them after five days. She could drink water and take liquid food. Solid food was regurgitated immediately after ingestion. Rectal temperature was normal but she lost 0.84 kg of body weight. Complete blood count and biochemistry values were normal. Radiographic examination didn’t reveal any cause of regurgitation. At this point we decided to do a flexible endoscopy examination of esophagus, which revealed 4 mm diameter stricture in distal part of thoracic esophagus.
Management and Outcome :
Dog was put under general anesthesia and intubated. Olympus GIF Q10 flexible gastroscope with 2.8 mm working channel was introduced into esophagus. After this, Olympus SWIFT balloon catheter (model BE – 6 ) was introduced through the working channel into the stricture ( through the scope method ). To generate force for stricture dilatation, catheter was expanded using saline and hand held Swift pump, two times for duration of two minutes. Steroid ( tramcinolone 40 mg / ml ) diluted with saline 1 : 2 was injected submucosally in three places around the stricture ( Pictures 1 to 5 ). After procedure, we prescribed omeprazole ( 1 mg / kg PO q24h ) for 7 days. After three weeks whole procedure was repeated. On next check-up dog regained normal body weight and was eating solid food without any problems.
From a biomechanical perspective, all types of dilators ( balloons and bougies ) generate two types of forces on esophageal wall, radial stretch force which is responsible for dilatation and unwanted longitudinal shear force which can cause esophageal perforation ( Table 1 ).
Through the scope balloon dilatation of esophageal strictures is an easy and relatively safe procedure. Stricture dilatation occurs because saline filled balloon transfers radial stretch force on esophageal wall. Complications like esophageal preforation rarely occur when using balloon catheters because of low longitudinal shear force. Mean shear force of balloon catheters is 1,44 N. Low shear force of balloon catheters is associated with significantly lower risk for perforation.
When using other types of dilators like bougies, in theory perforations are more likely to occur because of strong radial and shear forces.Bougies involve passing long rigid instrument ( rigid cylindrical tube ) through the stricture blindly or by endoscopic guidance. Advancing bougie through stricture generates radial force which causes dilatation of stricture, but it also generates strong shear force which can cause perforation. Mean shear force when using bougies is 16,92 N for Maloney type and 6,92 N for Savary – Gilliard bougie.
Steroid injection prior or after dilatation improves outcome because it’s decreasing scar formation and need for repeated dilatations. Most cases will need repeated procedure in three weeks. If the dog is eating normally after 3-4 weeks it probably wont need new dilatation procedure.
After procedure, anti-acids are prescribed to reduce potentially negative effect of gastric acid on new scar formation. Use of proton pump inhibitors like omeprazole is recommended because of better effect than H2 receptor antagonists ( ranitidine, famotidine ).
We are thankful to Mr. Silvijo Tarasić and Olympus d.o.o. Zagreb who provided technical expertise that greatly assisted us in implementing new technology improvements in our practice.
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