The esophagus is a muscular tube that transports food and water from the mouth to the stomach. Normally, waves of muscular contractions called peristalsis propel food and water along the length of the esophagus to the stomach. Megaesophagus (ME) is a condition in which there is enlargement and poor peristalsis of the esophagus.
Most commonly, ME develops in adult animals as an acquired condition. However, certain breeds are at risk for congenital ME, meaning they are born with ME. These breeds include the Irish Setter, Great Dane, German Shepherd, Labrador Retriever, Chinese Shar-Pei, Newfoundland, Miniature Schnauzer, and Fox Terrier dogs as well as Siamese cats.
The most common cause of ME in adult animals is idiopathic. Idiopathic means that an underlying cause is not identified. It is a diagnosis made by eliminating other potential causes first. Acquired ME in adult animals may be caused by:
- Esophagitis (inflammation of the esophagus)
- Myasthenia gravis (a chronic immune mediated disease between the muscles and nerves)
- Hypoadrenocorticism (aka Addison’s disease)
- Toxins such as lead, organophosphates, botulism or tetanus
- Other causes are infrequently identified
Megaesophagus may also occur in just a segment of the esophagus if there is an obstruction such as a swallowed foreign object, a tumor, a stricture (scar tissue) or if there is a vascular ring anomaly (a congenital abnormality of blood vessels around the esophagus).
Signs & Symptoms
Since the esophagus is unable to propel food and water into the stomach, it accumulates within the esophagus. This may give the patient bad breath and a gurgling sound coming from the throat. The chief symptom of ME is regurgitation (passively bringing up food, water or mucous). Patients with congenital ME typically start regurgitating shortly after weaning. Regurgitation puts the patient at risk of aspiration pneumonia. Symptoms of pneumonia include a moist cough, labored breathing and fever. In a patient with acquired ME, there may be other symptoms related to the underlying cause, such as weakness or stiff gait.
Diagnosis of ME can often be made with radiographs (“X-rays”). The radiographs should also be evaluated for concurrent pneumonia. If radiographs are equivocal, than fluoroscopy may be performed. Fluoroscopy is a cinematic radiograph, so peristalsis of the esophagus can be observed. For this diagnosis, the patient swallows a liquid called contrast, which highlights the esophagus.
Once ME is diagnosed, additional tests are recommended to look for an acquired cause. These tests may include routine bloodwork and urinalysis, an acetylcholine receptor antibody titer to test for myasthenia gravis, cortisol levels to screen for hypoadrenocorticism, blood lead levels, and esophagoscopy (endoscopic evaluation of the esophagus) to look for an obstruction.
Treatment & Aftercare
Patients with acquired ME are treated for their underlying disorder. If an obstruction is present, endoscopic treatment may be used to relieve the obstruction. Medications are indicated for diseases such as myasthenia gravis. Dependent upon how severe the ME was, it may not resolve. For patients with congenital or idiopathic ME and for those patients with unresponsive acquired ME, care is supportive. Unfortunately, there are no medications able to improve esophageal peristalsis. However, patients with ME are often prescribed medications to decrease acid reflux.
The mainstay of care is feeding small, frequent meals in an upright position. This position uses gravity to move food and water along the esophagus. Using a Bailey chair can facilitate upright feeding. The patient should remain upright for 15 to 30 minutes after eating or drinking. There are several websites (e.g. baileychair.blogspot.com, www.caninemegaesophagus.org) that provide instruction on Bailey chair construction.
The consistency of food best suited for a particular ME patient requires trial and error including:
- Meatballs of canned food
- Food moistened to a soupy consistency
- Some patients have more difficulty with water than with food. There are products available (e.g. Thick-It®) that can be helpful for those patients.
For patients whose symptoms are not controlled through upright feeding or who find a Bailey chair uncomfortable to use, than a permanent feeding tube can be placed. This tube goes through the side directly into the stomach, bypassing the esophagus altogether.
Long-term prognosis for ME is guarded as patients are usually euthanized due to repeated bouts of pneumonia. However, for owners able to dedicate the significant amount of time and care needed for management of ME and patients that adapt well, affected patients can have a good quality of life.
Figure 1 – Esophagus of a normal dog
Figure 2 – Esophagus of a dog with megaesophagus
Fact Sheet Author:
Karen M. Tefft, DVM, MVSc, Diplomate ACVIM (SAIM)