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Disorders of the Esophagus

1
Silvia Funes, DVM, MS, DACVIM (SAIM) and Craig Ruaux, BVSc (Hons), PhD, MACVSc, DACVIM (SAIM) 2
1 VCA Bay Area Veterinary Specialists and Emergency Hospital, San Leandro, CA, USA
2 School of Veterinary Science, Massey University, Palmerston North, New Zealand

Normal Esophageal Anatomy cleared of material. Relaxation of the lower esophageal
and Physiology sphincter accompanies the primary peristaltic wave,
allowing entry of the food bolus into the stomach.
The esophagus is a readily distensible, muscular tube The most common esophageal disorders encountered
that transports ingested material from the oropharynx to in private practice include esophagitis, megaesophagus,
the stomach. It is divided into three sections –the cervi- esophageal strictures, and esophageal foreign bodies.
cal, thoracic and abdominal segments – and enclosed at Less commonly encountered disorders include great
each end by a muscular sphincter (the upper and lower vessel anomalies, lower esophageal hiatal disorders,
esophageal sphincters). esophageal neoplasia, spirocercosis, cricopharyngeal
The esophageal wall has four distinct layers: adventi- dysphagia, esophageal diverticulae, and esophageal
tia, muscularis, submucosa, and mucosa. The entire fistulae.
muscularis layer in the canine esophagus is composed of
skeletal muscle, whereas the distal one‐third of the feline
esophagus consists of smooth muscle. This difference in Recognition of Esophageal
muscular structure may partly explain the differing prev- Disorders
alence of esophageal disease in dogs and cats, with cats
relatively rarely presenting with esophageal diseases Common clinical signs of esophageal disease include
other than foreign bodies or squamous cell carcinoma. regurgitation, dysphagia (difficult swallowing), ptyalism
The upper esophageal sphincter is composed of fibers (excessive salivation), extension of the head and neck,
from the cricopharyngeus muscle and thyropharyngeus repeated swallowing attempts, and pain. Regurgitation is
muscle. In dogs, the lower esophageal sphincter is a hallmark sign of esophageal disease and needs to be
composed of an outer layer of striated muscle and an differentiated from vomiting. Regurgitation is defined as
inner layer of smooth muscle, while in cats the lower the passive retrograde expulsion of material from the
esophageal sphincter consists of smooth muscle only. esophagus while vomiting is an active process mediated
Swallowing is a complex motor reflex requiring coor- by a central reflex. Vomiting is usually associated with
dinated action of the tongue, oropharynx, upper esoph- abdominal contractions and might show prodromal signs
ageal sphincter, and esophagus to ensure that food of nausea (lip smacking, increased salivation, discomfort
enters the gastrointestinal tract and not the upper air- or anxiety) or the presence of bile in the ejected material.
ways. When swallowing is not occurring, the upper and Oropharyngeal dysphagia, a less common clinical
lower esophageal sphincters are tightly closed and the syndrome, should be differentiated from regurgitation.
esophagus is relaxed. During swallowing, the upper Clinical signs of oropharyngeal dysphagia include multiple
esophageal sphincter relaxes and the food bolus is swallowing attempts with a single bolus, dropping food or
pushed into the cervical section of the esophagus. A pri- water from the mouth or nostrils, and difficulty drinking.
mary peristaltic wave is generated, transferring the When possible, having the owner video record the epi-
bolus to the stomach. This primary peristaltic wave will sodes may be helpful in distinguishing oropharyngeal
be followed by secondary waves if the esophagus is not swallowing disorders from esophageal motility disorders.

Clinical Small Animal Internal Medicine Volume I, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical