Esophageal Stricture

Esophageal stricture is a pathological narrowing of the esophageal lumen resulting from cicatricial contraction of fibrous tissue within the esophageal wall. This condition can be congenital or acquired, with acquired strictures being more common in veterinary patients. The stricture may be focal or diffuse, and it can occur at any level of the esophagus, though the cervical and caudal thoracic segments are most frequently affected. The severity of the stricture is graded based on the degree of luminal compromise, which directly influences clinical signs and therapeutic approach. Esophageal strictures are significant because they impair the passage of ingesta, leading to regurgitation, malnutrition, and aspiration pneumonia. Surgical intervention is often required when conservative management fails, and the choice of procedure depends on the stricture's location, length, and chronicity.

The etiology of esophageal stricture in dogs and cats is multifactorial. The most common cause is gastroesophageal reflux (GER) during anesthesia, which leads to severe esophagitis and subsequent fibrosis. Other causes include ingestion of caustic substances (e.g., acids, alkalis), foreign body trauma, esophageal surgery, radiation therapy, and chronic vomiting. Congenital strictures are rare but may result from vascular ring anomalies or developmental defects. Iatrogenic causes include prolonged esophageal intubation, nasogastric tube placement, and endoscopic procedures. The underlying mechanism involves damage to the esophageal mucosa and submucosa, triggering an inflammatory response that leads to granulation tissue formation and ultimately fibrous scar contraction. The severity of the initial injury and the duration of inflammation are critical determinants of stricture formation.

Esophageal stricture is an uncommon condition in small animal practice, with no strong breed or sex predilection reported. However, brachycephalic breeds may be at higher risk due to increased incidence of hiatal hernia and gastroesophageal reflux. Young animals may be more susceptible to congenital strictures, while acquired strictures are more common in middle-aged to older animals. Cats may be overrepresented in some studies, possibly due to a higher incidence of esophageal foreign bodies and caustic ingestions. The exact incidence is unknown, but it is a significant cause of esophageal dysphagia in dogs and cats.

The pathophysiology of esophageal stricture involves a sequence of events starting with mucosal injury. The esophageal mucosa is relatively unprotected against acid and pepsin, making it vulnerable to damage from refluxed gastric contents. The injury triggers an acute inflammatory response with neutrophil infiltration, edema, and epithelial necrosis. If the injury is severe or prolonged, the inflammatory process extends into the submucosa and muscularis, leading to fibroblast proliferation and collagen deposition. As the inflammation resolves, the collagen matures and contracts, resulting in a circumferential or segmental narrowing of the esophageal lumen. The stricture may be annular (ring-like) or tubular (longer segment). The degree of luminal compromise determines the clinical severity, with strictures reducing the lumen by more than 50% typically causing significant regurgitation.

Predisposing factors for esophageal stricture include any condition that increases the risk of gastroesophageal reflux, such as hiatal hernia, gastric dilatation-volvulus, and prolonged anesthesia without appropriate fasting. The use of certain anesthetic agents that decrease lower esophageal sphincter tone (e.g., anticholinergics) may also contribute. Other factors include the presence of esophageal foreign bodies, which can cause direct mucosal injury, and a history of esophageal surgery, which can lead to ischemia and subsequent fibrosis. Nutritional factors, such as feeding dry kibble to animals with esophageal motility disorders, may exacerbate the condition. Additionally, chronic kidney disease and hypergastrinemia can increase gastric acid secretion, predisposing to reflux esophagitis.

The most common clinical sign of esophageal stricture is regurgitation, which typically occurs shortly after eating. Regurgitated material is undigested and may contain mucus or saliva. Affected animals may also exhibit dysphagia, odynophagia (painful swallowing), excessive salivation, and weight loss. In severe cases, complete obstruction can lead to anorexia and dehydration. Aspiration pneumonia is a common complication, presenting with coughing, fever, and respiratory distress. Physical examination may reveal poor body condition, dehydration, and evidence of pneumonia on thoracic auscultation. In some cases, a palpable cervical mass may be detected if the stricture is associated with a foreign body or mass lesion.

Differential diagnoses for esophageal stricture include: 1) Esophageal foreign body: typically acute onset, may be visible on radiographs, and can cause similar obstruction. 2) Esophageal neoplasia (e.g., squamous cell carcinoma, leiomyosarcoma): usually in older animals, may have a palpable mass, and imaging shows a space-occupying lesion. 3) Vascular ring anomaly (e.g., persistent right aortic arch): congenital, presents in young animals with regurgitation, and radiographs show megaesophagus cranial to the heart base. 4) Esophageal diverticulum: outpouching of the esophageal wall, may cause regurgitation, and is diagnosed with contrast radiography. 5) Megaesophagus: generalized esophageal dilation due to motility disorders, often idiopathic or secondary to myasthenia gravis, and is characterized by a dilated esophagus on radiographs. 6) Esophagitis: inflammation without stricture, may cause similar signs but is usually transient and responsive to medical therapy. 7) Hiatal hernia: displacement of the stomach into the thoracic cavity, can cause reflux and regurgitation, and is diagnosed with thoracic radiographs or fluoroscopy.

The diagnostic algorithm for esophageal stricture begins with a thorough history and physical examination, focusing on regurgitation and potential aspiration. Thoracic radiographs (lateral and ventrodorsal views) are essential to evaluate for megaesophagus, foreign bodies, or masses. If radiographs are inconclusive, an esophagram using barium sulfate or a water-soluble contrast agent is performed to identify the location and extent of the stricture. Fluoroscopy can assess esophageal motility and identify functional abnormalities. Esophagoscopy is the gold standard for diagnosis, allowing direct visualization of the stricture, assessment of mucosal health, and collection of biopsy samples. In cases where a vascular ring anomaly is suspected, advanced imaging such as CT angiography may be indicated. The diagnostic workup should also include a complete blood count, serum biochemistry, and urinalysis to assess overall health and rule out underlying diseases.

Laboratory findings in esophageal stricture are often nonspecific. Complete blood count may reveal leukocytosis with a left shift if aspiration pneumonia is present. Serum biochemistry may show dehydration (elevated BUN and creatinine) and electrolyte imbalances (hypokalemia, hypochloremia) due to chronic regurgitation and poor intake. In cases of chronic malnutrition, hypoalbuminemia may be present. If an underlying cause such as hypoadrenocorticism or myasthenia gravis is suspected, specific tests (ACTH stimulation, acetylcholine receptor antibody titers) may be performed. Arterial blood gas analysis may be indicated if respiratory compromise is present. Inflammatory biomarkers such as C-reactive protein (CRP) may be elevated in cases of severe esophagitis or pneumonia.

Imaging plays a crucial role in the diagnosis and management of esophageal stricture. Thoracic radiographs may show a dilated esophagus cranial to the stricture, with or without signs of aspiration pneumonia (alveolar pattern in the dependent lung lobes). A barium esophagram is the most useful radiographic study, demonstrating a focal or segmental narrowing with dilation proximal to the stricture. The stricture may appear as a smooth, annular constriction or a longer, irregular narrowing. Fluoroscopy can assess esophageal motility and identify functional abnormalities such as megaesophagus. Computed tomography (CT) with contrast can provide detailed information about the esophageal wall and surrounding structures, particularly in cases of suspected neoplasia or vascular ring anomalies. Esophagoscopy is both diagnostic and therapeutic, allowing direct visualization and balloon dilation.

Cytology and histopathology are important for differentiating strictures from other causes of esophageal obstruction. During esophagoscopy, biopsy samples of the stricture site and adjacent mucosa should be obtained. Histopathology typically reveals fibrous connective tissue with varying degrees of inflammation, epithelial ulceration, and granulation tissue. In chronic strictures, dense collagen deposition and atrophy of the muscularis may be seen. If neoplasia is suspected, cytology of fine-needle aspirates or biopsy samples can identify malignant cells. Special stains, such as Masson's trichrome, can highlight collagen fibers and confirm fibrosis. In cases of eosinophilic esophagitis, eosinophilic infiltration may be prominent, suggesting an allergic or parasitic etiology.

Treatment of esophageal stricture can be medical or surgical, depending on the severity and chronicity. Medical management includes the use of anti-inflammatory drugs (e.g., prednisone at 0.5-1 mg/kg PO q12h for 2-4 weeks), gastric acid suppressants (e.g., omeprazole at 0.7-1 mg/kg PO q12h), and prokinetic agents (e.g., metoclopramide at 0.2-0.4 mg/kg PO q8h) to reduce reflux and promote healing. Dietary modification, such as feeding a soft or liquid diet, can help reduce mechanical irritation. For strictures that are refractory to medical therapy, balloon dilation during esophagoscopy is the first-line interventional treatment. This procedure involves passing a balloon catheter through the stricture and inflating it to progressively larger diameters over multiple sessions. Success rates are high, but repeated dilations may be necessary. Surgical options include esophageal resection and anastomosis for short, focal strictures, or esophageal patch grafting using a pedicled flap of the diaphragm or stomach. In cases of severe, diffuse strictures, esophageal replacement with a jejunal or colonic interposition graft may be considered, though this is technically challenging and associated with high morbidity. Postoperative care includes nutritional support via a feeding tube (e.g., esophagostomy or gastrostomy tube) and strict monitoring for complications such as leakage, dehiscence, and recurrent stricture.

The prognosis for esophageal stricture is variable and depends on the underlying cause, severity, and response to treatment. With early and aggressive medical management, some strictures may resolve without intervention. Balloon dilation is successful in approximately 70-90% of cases, with many animals requiring multiple dilation sessions. The prognosis is worse for long, tubular strictures, which are more difficult to dilate and have a higher recurrence rate. Surgical resection and anastomosis carry a guarded prognosis due to the risk of anastomotic leakage and stricture recurrence. The overall long-term outcome is good to excellent for animals with focal strictures that respond to dilation, but poor for those with diffuse disease or concurrent megaesophagus. Complications such as aspiration pneumonia and malnutrition can negatively impact survival.

Follow-up care for esophageal stricture is essential to monitor for recurrence and manage complications. After balloon dilation, animals should be re-evaluated with esophagoscopy 2-4 weeks later to assess the response and determine if further dilation is needed. Serial thoracic radiographs may be performed to monitor for aspiration pneumonia. Dietary modifications should be continued for several weeks, and a gradual transition to a more normal diet can be attempted once the stricture is adequately dilated. Owners should be instructed to feed small, frequent meals and to keep the animal upright for 10-15 minutes after eating to reduce reflux. Long-term monitoring includes regular weigh-ins to ensure adequate nutrition and observation for signs of regurgitation or respiratory distress. If a feeding tube was placed, it should be maintained until the animal is eating adequately on its own.

Clinical pearls: 1) Always consider gastroesophageal reflux as a cause of esophageal stricture, especially in animals with a history of anesthesia. 2) Early esophagoscopy is crucial for diagnosis and to guide treatment. 3) Balloon dilation should be performed gradually, with a target diameter of 50-75% of the normal esophageal diameter to reduce the risk of perforation. 4) Use of a guidewire during balloon dilation can help ensure correct placement. 5) Post-dilation, administer a short course of glucocorticoids to reduce inflammation and prevent re-stricture. Pitfalls: 1) Avoid aggressive dilation, as it can lead to esophageal perforation and mediastinitis. 2) Do not neglect to treat underlying reflux, as it can lead to recurrence. 3) Be cautious with the use of nonsteroidal anti-inflammatory drugs, as they can exacerbate esophagitis. 4) In cases of suspected vascular ring anomaly, do not perform dilation without first ruling out the anomaly, as it will not resolve the obstruction.

Perioperative pharmacological protocols for esophageal stricture management include: 1) Prophylactic antimicrobials: Cefazolin (22 mg/kg IV) administered 30 minutes before surgery and repeated every 90 minutes during surgery. 2) Postoperative analgesics: Opioids such as buprenorphine (0.01-0.02 mg/kg IV or IM q8-12h) or fentanyl CRI (2-5 mcg/kg/hr) for 24-48 hours. 3) Anti-inflammatory drugs: Prednisone (0.5-1 mg/kg PO q12h) for 2-4 weeks, tapering over 2 weeks. 4) Gastric acid suppressants: Omeprazole (0.7-1 mg/kg PO q12h) or famotidine (0.5-1 mg/kg PO q12h) to reduce reflux. 5) Prokinetic agents: Metoclopramide (0.2-0.4 mg/kg PO q8h) or cisapride (0.5 mg/kg PO q8h) to enhance gastric emptying and lower esophageal sphincter tone. 6) Local anesthetic blocks: For cervical esophageal surgery, a cervical paravertebral block with bupivacaine (1-2 mg/kg) can provide postoperative analgesia. 7) Nutritional support: If a feeding tube is placed, a balanced liquid diet should be administered. 8) Antiemetics: Maropitant (1 mg/kg SC q24h) may be used to prevent vomiting and reduce reflux.

Evidence-based literature on esophageal stricture in dogs and cats is limited, but several studies provide guidance. A retrospective study by Leib et al. (2002) reported successful balloon dilation in 80% of dogs with esophageal strictures, with a median of 2 dilation sessions. Another study by Bissett et al. (2009) found that intralesional triamcinolone injections combined with balloon dilation reduced the number of dilation sessions needed. A case series by Melendez et al. (2010) described successful surgical management of cervical esophageal strictures using a pedicled sternothyroideus muscle flap. The ACVS consensus statement on esophageal stricture recommends balloon dilation as the first-line treatment, with surgical resection reserved for refractory cases. The use of proton pump inhibitors and prokinetics is supported by evidence from human medicine and extrapolated to veterinary patients. Overall, the prognosis is favorable for focal strictures, but long-term follow-up is essential to detect recurrence.