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Megaesophagus is a condition in which the muscles of the esophagus lose their tone and are no longer able propel food into the stomach. The esophagus is a tube which connects the mouth to the stomach. In normal function wave-like contractions, called peristalsis, move the food which enters the esophagus down into the stomach. When megaesophagus occurs the esophagus dilates, or enlarges, due to the lack of muscle tone. This causes food to just sit in the esophagus, unable to continue into the stomach to be digested.
Although any breed of dog can develop megaesophagus there are a few breeds which seem to be at a higher risk for it. These include the Great Dane, Irish Setter, Newfoundland, German Shepherd, Shar Pei, Labrador Retriever, and Miniature Schnauzer. If you suspect your dog may have megaesophagus contact your local veterinarian.
Megaesophagus can be a congenital defect or acquired as an adult. In cases where megaesophagus presents in young dogs it can be caused by vascular ring anomalies, a persistent right aortic arch, or it may be idiopathic (unknown cause). In acquired cases seen in adult dogs megaesophagus can be primary or secondary. The cause of primary megaesophagus is idiopathic, while secondary megaesophagus is a result of another disease. The most common cause of secondary megaesophagus is the disease myasthenia gravis. Secondary megaesophagus due to an underlying disease is not normally seen; in most cases there is no known cause for the development of megaesophagus.
The most common symptom of megaesophagus is regurgitation. It is important to understand the difference between regurgitation and vomiting. Vomiting is an active process associated with retching and heaving, where the body forcefully removes contents from the stomach. Regurgitation is a passive process where food or water basically just falls back out of the mouth or throat with no warning. Regurgitation is associated with megaesophagus because food is not able to be moved into the stomach and so it sits in the esophagus until it eventually is removed from the body by the process of regurgitation. Another sign can be weight loss. Because food is not making it to the stomach it cannot be broken down or the nutrients absorbed. This can result in malnourishment and weight loss. A very common complication associated with megaesophagus is aspiration pneumonia. Because food remains in the esophagus it can easily get into the lungs. This causes pneumonia which can be fatal if not treated. This is most often the cause of death in dogs with megaesophagus.
Megaesophagus is diagnosed by radiographs. The x-ray can show air, food, and/or fluids in a dilated esophagus. In some cases a contrast study may be done to enhance the image to make a more conclusive diagnosis. In the study barium is given with the dog's food and then an x-ray is taken to show the structure of the esophagus. Radiographs can also be used to determine if aspiration pneumonia is present and too look for underlying causes.
There is currently no cure for megaesophagus and surgery has not proven to be helpful in treating the condition. Medical therapy has been helpful in some cases and shown no effects in others. The main treatment method for the condition is life style management. Food consistency should be the first issue addressed. No one type of food has been found to be the best. You must determine what works best for your dog. Some options are liquid diets, dry food, canned food or any combination of the three; when you find a food that works well for your dog stick with it. Feedings should be given in frequent, small meals as opposed to few, large meals. Elevated feeding should be practiced as this uses gravity to pull the food into the stomach keeping it from just settling in the esophagus. This can be done my using a step ladder or a Bailey chair. To use the step ladder food should be placed on the 3rd or 4th step. The dog's back legs should remain on the floor. This places the dog in a position to allow gravity to work. A Bailey chair is a specially designed chair that allows the dog to sit upright (like a begging position) while eating. In whatever set up you choose or find that works best for your dog, always keep them in the elevated position for at least 10 minutes to allow all the food to make its way into the stomach. Another option for managing megaesophagus is to have a feeding tube inserted. In this practice a tube is surgically placed into the stomach allowing the animal to be fed while bypassing the esophagus completely.
There are a few medications which may be given to treat megaesophagus. Metoclopramide helps increase the muscle tone of specific areas around the esophagus, antacids help minimize the damage to the esophagus, and nausea medication may help the dog feel better overall. Cisapride has been known to be helpful in cases of megaesophagus but is not available in the United States. One should always remember that medical therapy may or may not be helpful to your dog.
Along with the feeding adjustments, owners must be able to recognize the signs of aspiration pneumonia. This potential complication of megaesophagus can be fatal if not treated, and is the most common cause of death in megaesophagus dogs. Signs of this pneumonia include coughing, fever, and lethargy. For more information about the disease itself and how to manage it you can join the yahoo group dedicated to megaesophagus.
CHF has funded grant on ME in the German Shepherd Dog. This study is looking for the genetic causes of the disease.
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