Equine Esophageal Obstruction and Trauma – NAVLE Study Guide

Overview and Clinical Importance

Esophageal obstruction, commonly known as choke, is the most common esophageal disease in horses and represents a frequent equine emergency. Unlike choking in humans where the airway is blocked, equine choke involves obstruction of the esophagus, meaning horses can still breathe. However, this condition requires urgent attention due to potential life-threatening complications including aspiration pneumonia, esophageal ulceration, stricture formation, and rarely, esophageal rupture.

The equine esophagus is approximately 1.2 to 1.5 meters in length and extends from the pharynx to the stomach. A key anatomical feature is the well-developed cardiac sphincter at the gastroesophageal junction, which prevents horses from vomiting. The proximal two-thirds of the equine esophagus consists of skeletal (striated) muscle, while the distal one-third is composed of smooth muscle. This distinction is clinically important for pharmacological management.

Etiology and Risk Factors

Classification of Causes

Risk Factors

• Dental disease: Poor dentition leads to inadequate mastication, allowing large, poorly chewed boluses
• Bolting feed: Rapid eating, especially in competitive feeding situations
• Dehydration: Inadequate water intake prevents proper hydration of feed material
• Post-sedation feeding: Eating while heavily sedated impairs swallowing reflex
• Breed predisposition: Friesians (megaesophagus, idiopathic muscular hypertrophy); American Miniature Horses anecdotally overrepresented
• Previous choke: Esophageal scarring from prior episodes increases recurrence risk
• Age: Geriatric horses with worn teeth; foals with congenital abnormalities

Clinical Signs

Clinical presentation varies based on duration and completeness of obstruction. Signs result from the inability to swallow saliva, water, or feed, which pools in the pharynx and exits through the nostrils.

Diagnosis

Physical Examination

• Observation: Bilateral nasal discharge with feed material, neck extension, distress
• Palpation: Cervical esophagus on left side of neck in jugular furrow - may feel firm mass if obstruction is cervical
• Oral examination: Assess for feed in mouth, dental abnormalities
• Auscultation: Evaluate lungs for evidence of aspiration (crackles in cranioventral lung fields)

Diagnostic Procedures

Laboratory Findings

Laboratory abnormalities reflect dehydration from excessive saliva loss and inability to drink. Chronic obstruction may show: hyponatremia, hypochloremia, and hypokalemia (electrolyte loss in saliva). CBC may reveal leukocytosis, left shift, toxic neutrophils, and hyperfibrinogenemia in complicated cases with aspiration pneumonia or esophageal rupture.

Treatment

Initial Management

• Remove access to feed and water immediately - prevents worsening of obstruction and aspiration
• Keep horse calm in a familiar, confined area
• Allow head to hang low to facilitate drainage of saliva and prevent aspiration
• Gentle neck massage in jugular furrow using downward motion may help move the obstruction

Medical Management

Esophageal Lavage Procedure

• Heavily sedate horse to ensure low head carriage
• Position head LOWER than body to prevent aspiration
• Pass nasogastric tube to level of obstruction
• Gently lavage with warm water using stomach pump
• Allow water and feed material to drain from nostrils
• Advance tube carefully - do NOT force
• Confirm resolution by passing tube into stomach or by endoscopy

Complications

Aspiration Pneumonia Treatment Protocols

Esophageal Trauma and Perforation

Esophageal perforation is a rare but serious complication that can occur secondary to prolonged obstruction, iatrogenic injury during nasogastric intubation, external trauma (kicks), or extension of soft tissue infections. The prognosis varies significantly based on location: cervical perforations have a fair prognosis with appropriate management, while intrathoracic perforations carry a grave to poor prognosis due to septic mediastinitis and pleuropneumonia.

Clinical Signs of Esophageal Rupture

• Cervical rupture: Subcutaneous emphysema, cervical swelling and cellulitis, fever, pain, dysphagia
• Thoracic rupture: Pyrexia, tachycardia, tachypnea, vague colic signs, progressive septic pleuropneumonia, pneumomediastinum
• Both: Endotoxemia, depression, inappetence

Management of Esophageal Perforation

• Acute wounds (less than 12 hours): Primary closure if tissue is viable
• Chronic wounds (greater than 12 hours): Surgical debridement, ventral drainage, heal by second intention
• Esophagostomy tube placement: For nutritional support bypassing the injury site
• Broad-spectrum antibiotics: Penicillin + aminoglycoside + metronidazole
• IV fluids and NSAIDs
• Tetanus prophylaxis

Special Considerations: Friesian Horses

Friesian horses have a significantly higher prevalence of esophageal disease compared to other breeds. The most commonly recognized condition is megaesophagus, often associated with idiopathic muscular hypertrophy of the caudal esophagus. This breed predisposition is thought to be related to a connective tissue disorder. Megaesophagus causes dilation of the esophagus (typically in the thoracic region), poor motility, and predisposition to recurrent choke.

Diagnosis in Friesians

• Esophagoscopy: Visualize dilated segments, assess motility, identify complications
• Barium swallow study: Most reliable for diagnosing megaesophagus; shows dilation and transit abnormalities
• Combination of both recommended for accurate diagnosis

Management

There is no curative treatment for megaesophagus. Management focuses on dietary modification: feed soaked, sloppy pelleted feeds; avoid dry hay and large treats; provide continuous access to water; feed from ground level. Many horses with megaesophagus can lead productive lives with proper management.

Post-Treatment Care and Follow-Up

• NPO period: Withhold feed for 12-24 hours after resolution to allow esophageal rest
• Gradual refeeding: Start with water-soaked pelleted feed; avoid hay initially
• Without mucosal ulceration: Soaked pelleted feed for 7-14 days
• With mucosal ulceration: Soaked pelleted feed for 60 days; follow-up endoscopy to assess healing and stricture formation
• Prophylactic antibiotics: Recommended for all cases lasting greater than 4 hours or with tracheal contamination
• Thoracic ultrasound: Recommended at 24-72 hours to evaluate for aspiration pneumonia
• Endoscopy: All chronic or recurrent cases should have post-resolution endoscopy to identify underlying causes

Prevention Strategies

• Regular dental care: Annual examination and floating to ensure proper mastication
• Soak dried feeds: Allow pellets and beet pulp to fully hydrate before feeding
• Cut treats appropriately: Slice carrots and apples into small pieces
• Continuous water access: Ensure clean, fresh water is always available
• Slow feeding: Use haynets, slow feeders, or place large rocks in feed buckets to prevent bolting
• Reduce competition: Feed horses separately to prevent rushed eating
• Withhold feed after sedation: Do not feed until sedation effects have fully worn off
• Identify and avoid trigger feeds: Some horses repeatedly choke on specific feeds

Prognosis

Memory Aids

"CHOKE" Mnemonic for Clinical Signs:

• C - Coughing and discharge from nose
• H - Head/neck extension and stretching
• O - Obvious distress and anxiety
• K - Keep away from food and water immediately
• E - Esophagus is blocked (not airway - horse can breathe!)

"Friesian = Four Fs" Memory Aid:

• Friesian breed
• Frequent choke episodes
• Floppy esophagus (megaesophagus)
• Feed management is key

"2/3 - 1/3 Rule" for Esophageal Muscle:

• Proximal 2/3 = Skeletal muscle = responds to alpha-2 agonists (Xylazine, Detomidine)
• Distal 1/3 = Smooth muscle = responds to oxytocin and Buscopan