Megesophagus is characterized by a defect in the contractility of its muscular wall, and an abnormal dilation of the esophagus along its entire length (in the generalized form) or only in a part of the structure (in the "segmental" form). The esophagus no longer contracts correctly hence not transporting food, saliva and water into the stomach successfully. This results in "pooling" inside the esophagus itself.
There are multiple causes of this condition including:
- Congenital (i.e. present at birth)
- Esophageal inflammation (esophagitis)
- Nerve disease and /or muscular abnormality
- Hormonal imbalance, for example: hypothyroidism
- Vascular anomalies
In 50% of cases, no cause can be established, and it is described as being "idiopathic".
How do I know if my dog has megesophagus?
The main symptom that you will be able to observe is the presence of regurgitation. We must differentiate regurgitation and vomiting; regurgitation is a passive phenomenon requiring no contractions of the abdominal muscles while vomiting is an active phenomenon calling for a contraction of the abdomen. Dogs with megaesophagus usually have a weight loss, bad breath (halitosis) and salivation.
The breeds in which this condition has been found congenitally include:
- German Shepherd
- Great Dane
- Fox Terrier
- Golden Retriever
- Labrador Retreiver
- Miniature Schnauzer
- Irish Setter
- Sharpei
- Newfoundland
How will my veterinarian diagnose megesophagus?
The symptoms themselves are often highly suggestive, but chest radiographs should clearly show a dilated esophagus. When in doubt, radiographs can be repeated using contrast material (e.g. barium, which shows up on X-ray) in a meal, so the esophagus can be better visualized.
The most serious complication is that when digestive fluid/food accumulates in the esophagus, frequent regurgitation ensues. This creates a serious risk of aspiration of digestive fluid and food into the lungs, hence often leading to pneumonia (aspiration pneumonia). Malnutrition and/or starvation are chronic risk factors.
Animation showing a video of stenosis of the esophagus by oesophagram:
How is megesophagus treated?
If a cause can be identified, the priority is to treat the underlying disease. If there is no known primary cause, symptomatic treatment should be implemented. Most of the treatment is aimed at merely managing the problem. Particularly successful is the "Bailey Chair" so that feeding and watering can be done in the vertical position; the dog must stay in this position for 20-30 minutes in order for gravity to encourage food to reach the stomach. A low-fat or low residue canned food fed in a milkshake-like consistency several times a day is also helpful.
Medications may include an acid reducer (like Pepcid-AD or Prilosec) 1 or 2 times per day; motility drugs (e.g. metoclopromide/reglan, cisapride/propulsid) to help empty the stomach and minimize reflux from the stomach into the esophagus; and/or an esophageal "bandage" for esophagitis, (carafate/sucralfate). Antibiotics for aspiration pneumonia, may also be required..
Recent technical advances include making use of a type of intra-esophageal prosthesis, although only very specialized centers will be able to offer this type of intervention.
What is the prognosis for megesophagus?
If a cause is found, and the dog reacts well to treatment of the underlying disease without developing bronchopneumonia, the prognosis is favorable. However in most cases, unless the pet responds well to the management considerations above, significant weight loss +/- repetitive episodes of bronchopneumonia will impede the quality of life of the pet leading to a grim outlook.
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