Certain diagnostic tests must be performed to make a definitive diagnosis of megaesophagus and exclude other disease processes that may cause similar symptoms. A complete history is especially important in these cases, as regurgitation, the most common clinical sign seen with megaesophagus is often referred to as vomiting by the pet owner.
A complete diagnostic evaluation is indicated in dogs with megaesophagus since an accurate diagnosis is important for both treatment and prognosis. A complete blood count (CBC) is often within normal limits, although with certain infections, inflammatory disorders or toxins, characteristic changes may be noted.
A biochemical profile may show changes consistent with endocrine disorders.
A urinalysis is usually within normal limits.
Chest X-rays may show an esophagus dilated with gas, fluid, or food.
An esophagram may be indicated to confirm megaesophagus, especially when mild dilation may not be obvious on plain radiographs. It is a non-invasive barium contrast X-ray.
An acetylcholine receptor antibody titer (ARAT) is a blood test that is performed when myasthenia gravis is suspected. Although there are usually other systemic signs associated with myasthenia gravis, megaesophagus may be the only sign in certain cases. The incidence of myasthenia gravis appears to be higher in German shepherd dogs and golden retrievers.
Antinuclear antibody titers are sometimes run to confirm immune-mediated diseases like systemic lupus erythematosus.
An ACTH stimulation test evaluates adrenal gland function and confirms the diagnosis of hypoadrenocorticism.
Serum creatine kinase (CPK) is a blood test that may be elevated in certain muscle diseases.
Blood lead levels are measured, especially in cases where lead toxicity is suspected due to history, environment, or changes in the blood count.
Thyroid function tests may be run to rule out hypothyroidism.
Your veterinarian may recommend additional tests to exclude or diagnose other conditions, such as the following:
Esophagoscopy is the visual inspection of the esophagus with a rigid or flexible scope. It is not routinely done in all cases of megaesophagus; however, it may be useful in cases of suspected or confirmed esophageal foreign bodies, neoplasia, or esophagitis (inflammation of the esophagus).
Dynamic contrast fluoroscopy is a video X-ray that allows visual observation of the esophagus in motion. It helps assess the strength and coordination of esophageal contractions that propel the food down into the stomach. It often requires referral of your pet to a veterinary institution with the specialized instrumentation capable of performing video X-rays.
Toxicology assays may be indicated for suspected toxicities, such as thallium or organophosphates.
Electrodiagnostic tests such as electromyography (EMG) and nerve conduction velocity (NCV) help to rule out neuromuscular diseases.
A tensilon test is a special test used to diagnose myasthenia gravis.
The primary goals in treating megaesophagus are to identify and treat the underlying cause, decrease the frequency of regurgitation, prevent over-distention of the esophagus, provide adequate nutrition, and treat complications such as aspiration pneumonia and esophagitis. In cases where a primary cause can be identified and treated, esophageal motility may improve with time. Treatment is symptomatic in animals in which an underlying cause cannot be identified.
Following appropriate feeding recommendations is of paramount importance, and although there is no single way that all animals should be fed, several general principals apply:
Elevated feedings allow gravity to aid movement of food through the esophagus. Medium and large dogs can be trained to eat with their front legs elevated on a table or rack. They should remain elevated at a 45-degree angle for 10 to 15 minutes after eating. Small dogs can be held upright (after eating) by their owners.
A diet must be formulated that provides adequate nutrition. Generally, a high calorie diet is fed in small amounts frequently over the course of the day. This regimen ensures adequate intake of nutrition and is less likely to cause over-distention of the esophagus.
Controversy still exists regarding the best-tolerated consistency of food. The diet consistency is tailored to each patient based on the diet that causes the fewest clinical signs. Some individuals do better with a more liquid diet, while others seem to tolerate more solid food. Using canned food rolled into small "meat balls" works well in many dogs.
Animals that cannot maintain an adequate nutritional balance may require tube feeding. Feeding tubes are usually placed surgically into the stomach, and may be left in place for several weeks.
Other treatment options include:
Drugs that improve movement of the gastrointestinal tract have been used with only limited success. Generally, these drugs are of benefit in cases where little esophageal distention exists.
There is no effective surgical treatment of megaesophagus; however, removal of a thymoma in the chest may be indicated.
Esophagitis is sometimes treated with drugs that decrease the acidity of the stomach contents. The regurgitated material from the stomach is therefore, less harmful to the lining of the esophagus. In addition, agents that coat and protect the esophagus may also be tried.
Animals with severe aspiration pneumonia require special attention and aggressive therapy.