The esophagus is a small hose-like tube which connects the mouth to the stomach. As it leaves the mouth, it follows a straight path through the neck and chest, passing near the heart through the diaphragm muscle and finally entering the stomach. The esophagus walls are composed of muscles which move in wave-like contractions to push food into the stomach. In the dog, it takes about five seconds for food to move from the mouth to the stomach. Surgery on the esophagus is always difficult because of its location within the chest and its slow rate of healing.
Megaesophagus describes a situation in which the esophagus has lost muscle tone. Rather than appearing like a muscular hose, it dilates into a thin 'bag-like' tube. Most cases are congenital and probably caused by a faulty nerve supply.
What are the symptoms?
Shortly after eating, the dog tends to regurgitate its food. The diseased esophagus lacks the muscle tone to move food to the stomach. Food is swallowed, but sits in the esophagus until regurgitated. Some food, particularly liquids, may pass into the stomach.
What are the risks?
Megaesophagus is usually a permanent situation. An infection or irritation of the nerve supply may only cause temporary symptoms, but this is rare. Megaesophagus is generally a permanent condition that must be managed.
What is the management?
Congenital megaesophagus has no known cure. Dogs affected with megaesophagus must be fed liquid diets. The food is usually placed in an elevated position so dogs eat while standing on their hind limbs. This elevated eating stance allows liquid food to travel to the stomach via gravity. With these precautions, many dogs can survive and do well.