Megaesophagus in Dogs: What Owners Need To Know

Vomiting and regurgitation are often signs that your pup needs to see a veterinarian. However, regurgitation and vomiting are different from one another. Vomiting involves the active expulsion of stomach contents. In other words, there is retching, gagging, and abdominal heaving associated with vomiting. Regurgitation involves the passive expulsion of stomach contents, meaning that there is no abdominal effort or retching.

Regurgitation is usually caused by a problem with the esophagus, the tube-like structure that connects the mouth to the stomach. Certain stomach disorders can lead to regurgitation, but the most common cause of regurgitation is megaesophagus.

Megaesophagus is the term applied when a dog has an enlarged esophagus. This is usually due to factors that affect nerves and muscles, but structural problems can also contribute to megaesophagus such as strictures or physical blockages.

The esophagus is composed of striated muscles which help to actively move food down from the mouth to the stomach. Nerves will send the signal to start the swallow reflex once food enters the dog’s mouth. When the muscles are diseased or nerve signals are blocked, the esophagus cannot move food down to the stomach. Instead, it may remain within the esophagus and dilate or stretch it out. Frequent food regurgitation is a sign that your dog may have megaesophagus.

Dogs with megaesophagus may also have an increased risk of aspiration pneumonia. This is when food or liquid enters the airways and gets into the lower respiratory tract. Aspiration pneumonia is a serious complication, often resulting in pulmonary edema and severe airway inflammation, leading to difficulty breathing. These patients require hospitalization and oxygen therapy.

Regurgitation is the most common sign of megaesophagus. These pups may try to eat very small amounts of food at a time because they know that eating a lot in one sitting will cause regurgitation. They may always be hungry, but these dogs may also appear thin as a result of not being able to eat enough food. Frequent regurgitation will also cause bad breath, and dogs with megaesophagus may make “gurgling” sounds when they swallow.

If a megaesophagus patient has developed aspiration pneumonia, you may notice difficulty breathing and coughing. Nasal discharge, abnormal lung sounds, and fever are also common signs. In cases with severe megaesophagus, you may see a bulge over the neck that is painful when touched.

For young puppies with megaesophagus, the condition is inherited. They will start to show signs by the time they start to eat solid foods. Miniature Schnauzers and Wire-Haired Fox Terriers are most likely to develop megaesophagus, and other breeds like German Shepherds, Labrador Retrievers, Great Danes, and Newfoundlands may be predisposed to it.

For young adults to middle-aged dogs, megaesophagus is acquired which means that there is some underlying cause besides genetics. Severe inflammation of the esophagus or esophagitis can also cause megaesophagus, and esophagitis itself can be caused by any number of diseases. Scarring or damage from a foreign body can cause a narrowing of the esophagus called a stricture which can obstruct it.

Any condition that causes nerve damage such as trauma, neurotoxin exposure, or myasthenia gravis can result in megaesophagus. Myasthenia gravis is thought to be the most common acquired cause of megaesophagus in dogs. It is an immune-mediated problem that attacks the junction between the nerves and muscles. Because of this, the swallow reflex signal is not conducted and megaesophagus results. Blood testing can help confirm a diagnosis, and dogs with myasthenia gravis are treated with a medication called pyridostigmine that is taken every day for the rest of their life.  

Addison’s disease is a condition where the adrenal glands do not produce enough cortisol. Cortisol is necessary for many functions in the body, especially for the cellular metabolism of the esophageal muscles. When there isn’t enough cortisol, esophageal muscle function diminishes. Lifelong use of steroid injections and tablets are necessary for the treatment of Addison’s disease.

Structural defects and physical obstructions can also result in megaesophagus. Esophageal tumors can obstruct the esophagus so that food becomes stuck behind it and dilates the esophagus. Tumors can also invade the esophageal walls and muscles, resulting in problems with motility down to the stomach.

Certain parasites like Spirocerca lupi can cause granulomas, which are raised areas that can develop inside of the esophagus. And in a condition known as persistent right aortic arch (PRAA), a small vessel that failed to disappear after a puppy’s birth traps the esophagus and becomes worse as the puppy grows. Surgery is necessary to ligate the vessel and free the esophagus.

Megaesophagus can be diagnosed via x-rays, and it is sometimes an incidental finding when a veterinarian starts off performing x-rays to look for aspiration pneumonia. The esophagus is normally invisible on x-rays, but megaesophagus is suspected when the borders of the esophagus are visible and wide or dilated. Since aspiration pneumonia can be more immediately life-threatening than megaesophagus, the former is treated first.

For conditions like myasthenia gravis, it may take many months of treatment before the esophagus is back to normal. Conditions like this and Addison’s disease will need to be treated for the life of the dog. If there is a PRAA, surgery is performed to remove the vessel that has trapped the esophagus, and for strictures, a balloon-like device may be placed into the esophagus to help open it up. However, depending on the severity of the stricture, it may reoccur even with the balloon technique.

For dogs with congenital megaesophagus, a high calorie diet is necessary because they can only consume small volumes of food at a time before regurgitating. Blenderized slurries of food or food meatballs may help to minimize the risk of regurgitation.

Feeding dogs upright with a Bailey chair is a great way to manage things long term. A Bailey chair can be purchased or built. It is a special box or highchair that allows dogs to be fed in a vertical position. Gravity helps to move the food down the esophagus. When using the chair, dogs should remain in a vertical position for at least ten to fifteen minutes after eating.

Megaesophagus can affect very young puppies or young to middle-aged adult dogs. Puppies with congenital megaesophagus may show signs right at weaning while acquired megaesophagus will cause gradual weight loss and muscle-wasting in adult dogs. Regurgitation is the most obvious symptom, and x-rays are the easiest way to diagnose it. Treatment will be based on the underlying cause, and long-term management like using a Bailey chair at feeding times can minimize regurgitation.