section name header

Basics ⬇

Outline

BASICS

Definition!!navigator!!

A partial or complete obstruction of the esophageal lumen by feed or foreign body that results in an inability to swallow. The disorder may occur as a single acute episode or as a chronic, intermittent problem.

Pathophysiology!!navigator!!

  • Esophageal obstruction occurs with higher frequency at sites with naturally decreased esophageal distensibility—the mid-cervical region, the thoracic inlet, and the terminal esophagus
  • The most common type of obstruction is impaction with feed material
  • Wood shavings and various foreign bodies can also cause obstruction of the esophagus
  • A frequent predisposing factor is improper mastication by older or younger horses caused by defective and erupting teeth, respectively. Improper mastication can also occur in gluttonous, sedated, or exhausted horses or in horses recovering from general anesthesia
  • Horses with preexisting lesions such as external esophageal compression, megaesophagus, and esophageal diverticulum or stricture experience recurrent obstructions at the affected site
  • Choke can also occur secondarily to neurologic disorders causing dysphagia

Systems Affected!!navigator!!

Gastrointestinal

Choke causes dysphagia. Sequelae to choke include esophageal perforation or stricture formation and megaesophagus.

Respiratory

Aspiration of feed material and saliva frequently occurs in horses with esophageal obstruction. This can lead to aspiration pneumonia and pleuropneumonia. Other less common sequelae to choke are pleuritis and mediastinitis secondary to esophageal perforation.

Cardiovascular

The inability to drink water may result in dehydration.

Skin/Exocrine

Esophageal perforation can result in cervical cellulitis and fistula formation.

Genetics!!navigator!!

N/A

Signalment!!navigator!!

Mean Age and Range

Younger and older horses.

Signs!!navigator!!

General Comments

Ptyalism and feed-containing nasal discharge are the most common clinical signs of choke. Other clinical signs vary with the duration and the degree of the obstruction. Partial obstruction might cause intermittent clinical signs depending on the diet.

Historical Findings

  • Frequent, ineffectual attempts to swallow
  • Retching
  • Repeated extension of the head and neck
  • Coughing during swallowing
  • Nasal discharge of saliva mixed with feed
  • Restlessness
  • Sweating
  • Anxiety

Physical Examination Findings

  • Dysphagia, coughing, ptyalism, and regurgitation of saliva and feed material through the mouth and nostrils
  • If the obstruction is located in the cervical esophagus, focal swelling may be palpated or visible
  • The presence of subcutaneous emphysema and/or cellulitis over the cervical region may indicate esophageal rupture
  • In cases of aspiration pneumonia, abnormal lung sounds such as crackles and wheezes can be present
  • In pleuropneumonia, no respiratory sounds are heard ventrally and chest percussion is dull ventrally too

Causes!!navigator!!

  • Obstruction of the esophagus is most frequently caused by intraluminal impaction of feed material or, less commonly, by foreign bodies
  • Improper mastication due to erupting or defective teeth, sedation, exhaustion, and fracture of the hyoid bone are potential predisposing factors to intraluminal feed obstruction
  • Dry feeds (e.g. beet pulp, pelleted feeds, oats) are most often associated with the condition
  • Defects in the esophageal wall (intramural lesions) such as strictures, intramural abscesses or cysts, esophageal diverticula, and neoplasia (especially squamous cell carcinoma) usually result in recurrent esophageal obstructions
  • Acquired lesions causing external esophageal compression are relatively rare and include abscesses, tumors, cervical cellulitis, and diaphragmatic hernia
  • Congenital disorders such as megaesophagus, achalasia, vascular ring anomalies, and right aortic arch are rare causes of esophageal obstruction
  • Esophageal motility disorders can result in esophageal obstruction and megaesophagus

Risk Factors!!navigator!!

  • Poor dental care
  • Rapid ingestion of feed
  • Poor quality feed; pelleted or dry feeds such as beet pulp and oats
  • Inadequate water intake
  • Previous episode of choke

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Other causes of bilateral nasal discharge, e.g. guttural pouch empyema, strangles, and lung edema
  • Neurologic disorders causing dysphagia, e.g. rabies, botulism, and guttural pouch mycosis affecting cranial nerves IX, X, and XII
  • Foreign bodies in the pharynx or oral cavity

CBC/Biochemistry/Urinalysis!!navigator!!

  • Neutrophilia or neutropenia as well as increased serum amyloid A protein and fibrinogen may be seen in cases that develop aspiration pneumonia
  • Prolonged excessive salivary loss may cause hyponatremia, hypochloremia, and metabolic alkalosis

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

Ultrasonography

Ultrasonography can be used to provide information about the location and extent of a cervical esophageal impaction.

Radiography

  • Radiographic evaluation of the esophagus supplies information concerning the nature and degree of the obstruction but is more commonly used for evaluation of patients with recurrent episodes
  • After relief of the impaction, contrast radiographic studies are useful to evaluate diverticulum formation, strictures, esophageal dilation, megaesophagus, and luminal narrowing secondary to extraluminal compression

Other Diagnostic Procedures!!navigator!!

  • Passage of a nasogastric tube can confirm a tentative diagnosis of esophageal obstruction and determine the approximate location of the obstruction
  • Endoscopic evaluation of the esophagus gives further information about the nature of the obstruction

Pathologic Findings!!navigator!!

N/A

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

  • Although some cases of esophageal obstruction resolve spontaneously, they should be treated as emergencies
  • Most cases of esophageal obstruction can be successfully treated on the farm. Only a few cases require referral to an animal hospital

Nursing Care!!navigator!!

  • The basic approaches to treatment of esophageal obstruction are gentle esophageal lavage in conjunction with administration of drugs that result in relaxation of the esophageal musculature and a reduced level of anxiety
  • In cases of mild obstruction, administration of these drugs alone may result in muscular relaxation to allow the obstruction to pass
  • A nasogastric tube is advanced to the level of the obstruction and small amounts of water are used for gentle lavage of the impaction site. The patient's head should be kept at a low level to facilitate the exit of fluid and prevent aspiration. The procedure requires patience and gentleness
  • Continuous lavage can be performed by passing a cuffed endotracheal tube into the esophagus and passing a smaller tube through the larger cuffed tube. Alternatively, a specially designed cuffed tube for treatment of esophageal obstruction (esophageal flush tube) can be used
  • If the impaction is not relieved, the lavages can be performed intermittently with the horse placed in a stall without access to feed, water, and bedding between the attempts
  • Refractory cases may be lavaged during general anesthesia with endotracheal intubation. General anesthesia provides optimal relaxation of the esophageal musculature
  • Most cases of esophageal obstruction do not require IV fluid therapy but should be given if the horse is dehydrated or water consumption is restricted

Diet!!navigator!!

  • The owner should be instructed to remove feed and water from the stall while waiting for the veterinarian to arrive
  • Esophageal dilatation post obstruction increases the likelihood of reimpaction for at least 48 h
  • In case with mild impactions without esophageal mucosal damage, horses can be fed small amounts of moistened pellets (soup) after 12–24 h. The amount can be increased as the condition improves
  • Small amounts of hay presoaked in water can be gradually introduced after a few days
  • In horses with more complicated impactions with mucosal damage and/or remaining dilated esophagus, feed should not be provided until these problems have resolved

Client Education!!navigator!!

  • The feeding regime after treatment is important in order to decrease the risk for reobstruction
  • There is a risk for aspiration pneumonia and the owner is advised to monitor the horse's body temperature for a couple of days after the treatment

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Administration of xylazine (0.25–0.5 mg/kg IV), detomidine (0.01–0.02 mg/kg IV), or acepromazine (0.05 mg/kg IV) provides sedation and muscle relaxation of the esophagus
  • The use of α2-adrenergic agonists has the advantage of causing lowering of the head, thereby facilitating the lavage and decreasing the likelihood of aspiration
  • Butorphanol can be used in combination with α2-adrenergic agonists
  • Anti-inflammatory drugs (e.g. flunixine meglumine) are used to control pain and treat inflammation

Contraindications!!navigator!!

Administration of lubricating agents, such as mineral oil, or softening agents, such as dioctyl sodium succinate, in order to facilitate the removal of an esophageal obstruction are contraindicated because they might be aspirated.

Precautions!!navigator!!

NSAIDs should be administered cautiously to dehydrated animals due to their potentially nephrotoxic effects.

Alternative Drugs!!navigator!!

Oxytocin (0.11–0.22 IU/kg IV) can be used to relax the esophagus but it may be associated with transient abdominal discomfort, sweating, and muscle tremors. Oxytocin should not be used in pregnant mares.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Endoscopy of the esophagus should be performed after the obstruction has been relieved in order to determine the presence and extent of esophageal lesions, establish the prognosis, and make recommendations for additional treatments and feeding regimen
  • Repeated esophageal endoscopies are indicated if mucosal damage has occurred. Strictures most often occur 15–30 days after mucosal damage
  • Thoracic auscultation and monitoring of body temperature may help identify aspiration pneumonia. Thoracic radiographs are indicated if aspiration pneumonia is suspected

Possible Complications!!navigator!!

  • Recurrent esophageal obstructions
  • Esophageal diverticulum
  • Esophageal stricture
  • Esophageal ulceration
  • Esophageal perforation
  • Cellulitis
  • Esophageal dilation
  • Mediastinitis
  • Aspiration pneumonia
  • Pleuritis

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

Aspiration pneumonia.

Age-Related Factors!!navigator!!

Younger and older horses are most commonly affected.

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

α2-Adrenergic agonists may induce premature parturition if used during the last trimester of pregnancy.

Synonyms!!navigator!!

Choke

Abbreviations!!navigator!!

NSAID = nonsteroidal anti-inflammatory drug

Internet Resources!!navigator!!

https://www.merckvetmanual.com/digestive-system/diseases-of-the-esophagus-in-large-animals/esophageal-obstruction-in-large-animals

Suggested Reading ⬆ ⬇

Sanchez CL. Esophageal disease. In: Reed SM, Bayly WM, Sellon DC, eds. Equine Internal Medicine, 3e. St. Louis, MO: WB Saunders, 2010:830–838.

Whithair KJ, Cox JH, Coyne CP, DeBowes RM. Esophageal obstruction in the horse. Compend Contin Educ Vet Pract 1990;1:91–96.

Author(s) ⬆

Author: Johan Bröjer

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa