Equis ISSN 2398-2977

Esophagus: obstruction

Introduction

• Esophageal obstruction is a relatively common cause of acute dysphagia and discomfort in the horse.
• Colloquially known as 'choke'.
• Cause: ingestion of material that when swallowed, becomes impacted in the esophagus and does not pass into the stomach.
• Signs: passage of ingesta and saliva down the nostrils, coughing, stretching of the neck, pain and distress.
• Diagnosis: usually based on clinical signs, but further diagnostic tests may be necessary in some cases.
• Treatment: many cases respond to medical treatment with sedatives and muscle relaxants. Some require nasogastric intubation and lavage. In a minority of cases this may be unsuccessful, and surgical treatment may prove necessary.
• Prognosis: in most cases this is good, however it depends on the severity of the impaction and the time elapsed before veterinary attention is received.

Pathogenesis

Etiology

• Ingested material becomes impacted in esophagus.
• Due to the shape of the esophagus, there are three main sites where this occurs:
  • At the thoracic inlet, as the esophagus curves up over the sternal notch to enter the thorax.
  • At the heart base, as the course of the esophagus changes direction to pass over the heart.
  • At the cardia and entrance to the stomach.

Predisposing factors

General

• Feeding of inadequately soaked sugar beet pulp, which, when eaten, continues to swell, and can become impacted.
• Feeding of inadequately chopped carrots, apples etc.
• Feeding at irregular intervals, greed or competition from other horses can result in an individual eating too fast, insufficiently masticating their food, which may then become impacted.
• Dental disease may also predispose to this condition if it results in inadequate mastication.
• Presence of a neck swelling such as an abscess/cellulitis or even a neoplastic lesion may make it more difficult for food to pass, thus predisposing to esophageal impaction.
• Esophageal strictures, diverticulum or megaesophagus will often predispose to recurrent choke Esophagus: stricture Esophagus: megaesophagus.
• Presence of neurologic disease affecting the nerves involved in swallowing, such as guttural pouch mycosis Guttural pouch: mycosis or grass sickness Grass sickness.
• Esophageal dysmotility.
• Ingestion of foreign bodies - rare as horses are generally discriminate feeders.
• Medication by boluses, particularly in small ponies.

Pathophysiology

• Ingested food particles, or foreign bodies become impacted in the esophagus due to their size, due to swelling, or due to primary problems with swallowing and peristalsis.
• Increased salivation is stimulated,
• There is a tendency for food particles and saliva to pass down the nose.
• The presence of impacted material in the esophagus causes pain and distress.
• Coughing and aspiration pneumonia may occur.

• Presence of obstruction in esophagus can, particularly if it continues to swell, cause pressure necrosis to the surrounding esophageal mucosa. Necrotizing esophagitis, ulceration, rupture or fistulation can follow.
• Shallow mucosal ulcers tend to heal well, but deeper lesions can lead to stricture formation on healing which can predispose to future problems.
• Aspiration of food particles can lead to the development of aspiration pneumonia Lung: pneumonia - aspiration.

Diagnosis

Treatment

Prevention

Outcomes