Megaesophagus

The esophagus is a long, muscular tube that connects the back of the mouth (pharynx) to the stomach. The opening of the esophagus into the pharynx is close to where the windpipe (trachea) enters the pharynx. The purpose of the esophagus is to transport swallowed food and water to the stomach. To do this, the esophagus normally uses a squeezing movement behind the food (peristalsis) to propel the material into the stomach within a few seconds after it is swallowed. After swallowing, the normal esophagus is empty and resembles a collapsed hose. Megaesophagus refers to a syndrome in which the esophagus is weak and flaccid and subsequently becomes much larger than normal (hence the term megaesophagus). This occurs because the weak, flaccid esophagus has no tone and does not propel ingested air, food, and water into the stomach; rather, these items stay in the esophagus and stretch it out of shape (dilatation). This syndrome is much more common in dogs than in cats and can occur in dogs of any age. There are many causes of this weakness, but the consequences tend to be similar regardless of cause. Affected pets usually regurgitate fluid and /or food. Regurgitation is much like vomiting, except that vomiting involves ejecting material from the stomach and intestines where as regurgitation involves emptying material from the esophagus or the back of the mouth. Regurgitation related to megaesophagus may occur soon after eating or hours later. Dogs may or may not lose weight, depending on how much food ultimately reaches the stomach. The most devastating side effect of this syndrome is having food, water, and saliva leak into the windpipe (trachea) and lungs (this leakage is called aspiration), subsequently causing pneumonia (i.e.' infection of the lungs). Because the esophagus and the trachea enter the pharynx so close to each other, it is easy for this to happen. In some instances, the dog had signs of aspiration (i.e., cough, labored breathing, and/or fever) despite the owner never seeing evidence of regurgitation. This is because the dog may regurgitate the material into its mouth and then reswallow it or inhale it without ever having that material ejected from the mouth. It only small amount of material are aspirated into the windpipe, cough will be the most obvious problem. This cough may be moist or dry. If larger amounts are inhaled and material reaches the lungs, pneumonia may occur, causing fever and labored breathing. Dogs can die from severe aspiration pneumonia. Sometimes nasal discharge occurs when regurgitated material is pushed from the pharynx into the back of the nose. If large amounts of material are aspirated and reach the lungs, the dog can develop sudden, sever pneumonia and they can even die from asphyxiation. Such a sudden death may occur any time, even if the dog has not been regurgitating for several weeks or months. Megaesophagus is diagnosed by taking radiographs (x-rays) of the chest, often after feeding a contrast agent (material visible on an x-ray) such as barium. It is important to obtain these radiographs because there are other problems that cause clinical signs resembling those of megaesophagus but require very different therapy (in some cases surgery). Because of the potentially devastating side effects of megaesophagus, it is wise to look for an underlying cause. Underlying causes are found only 15 to 25 percent of the time; however, finding such a cause may allow the veterinarian to treat the cause of the megaesophagus (which tends to be more successful) instead of the signs (which often fails to prevent aspiration). If an underlying cause cannot be found (termed "idiopathic" megaesophagus), then symptomatic therapy is provided. This consists of trying to help food traverse the diseases esophagus and reach the stomach. If food does not remain in the esophagus, it cannot be regurgitated and aspirated. Although there is substantial dog-to-dog variation, one generally makes the dog stand on its hind legs when it eats, so that is as nearly vertical to the ground (and like a person) as possible. The dog should remain in this position for 5 to10 minutes after eating. In doing this, we hope that gravity will help pull the food down into the stomach. Gruels are often fed in the hope that they will "slide" down the esophagus more easily than dry foods; however, some patients tolerate dry food or canned foods better than gruels. Feeding several small meals a day is usually preferred to feeding one or two large meals. Sometimes, drugs suck as cisapride help diminish regurgitation. Rarely, a tube can be placed through the skin and wall of the abdomen directly into the stomach (i.e., gastrostomy tube) so that the dog may be fed and watered without anything having go through the esophagus. This feeding technique does not eliminate all aspiration (the dog is still swallowing saliva), but it can help diminish aspiration. Gastrostomy tubes may allow dogs with idiopathic megaesophagus to live a nearly normal life, except for their manner of being fed and watered. The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.