19th Dec, 2022

Written by Dr Mirjam van der Wel, Veterinarian, Port Elizabeth

The oesophagus is a muscular tube that runs from the back of your dog’s throat to its stomach. Once swallowed, food should go one way: to the stomach.

Megaoesophagus is a condition where the oesophagus is abnormally enlarged. Food and liquid accumulates in the oesophagus, never quite making it to the stomach. Your dog will have difficulty swallowing and experience hyper salivation, coughing, regurgitation and weight loss.

Vomiting vs regurgitation

Vomiting is when the stomach actively expels its contents back out through the oesophagus. It’s accompanied by muscular contractions from the stomach, the diaphragm and the abdominal muscles. Your pet will heave, gag and retch as the stomach contents are actively brought back up. It causes salivation and nausea.

Regurgitation, on the other hand, is a passive action. Food and water in the oesophagus that haven’t made it to the stomach, just fall back out. This can happen immediately after eating/drinking or several hours later (the food/water has just been sitting in the oesophagus and never made it to the stomach). When an animal regurgitates, there’s no heaving, gagging or retching. The food/water just “falls out” through its mouth and nose. When this happens, your pet runs the risk of “inhaling” the food into the lungs, thus causing an aspiration pneumonia.

What causes Megaoesophagus

Megaoesophagus can occur for a number of reasons:

Primary (congenital) megaoesophagus

In the case of primary (congenital) megaoesophagus, the dog is born with the condition (manufacturing or genetic mistake) or it can develop later in life. Either the nerves that run to the oesophagus are defective or the oesophageal neuromuscular system hasn’t developed properly. Certain breeds are more prone to developing megaoesophagus.

In wire-haired Fox Terriers and Miniature Schnauzers the condition may be hereditary; other breeds, such as German Shepherds, Newfoundlanders, Great Danes, Irish Setters, Sharpeis, Greyhounds and Labrador Retrievers, appear to be more prone to developing the condition than other dogs. The condition is seen more frequently in Siamese cats than in other felines.

Secondary megaoesophagus

Secondary megaoesophagus can be caused by a number of disorders, including toxins, oesophagitis (inflammation of the oesophagus), foreign bodies, scar tissue, cancer of the oesophagus, endocrine conditions like Addison’s disease and hypothyroidism and Myasthenia gravis (this is a condition where there’s a malfunction in the transmission of signals between the nerves and muscles).

What are the symptoms?

The main symptom to look out for with megaoesophagus is regurgitation. Your dog may become reluctant to eat because, although it’s hungry, swallowing is uncomfortable.

Your adult dog will lose weight (not enough food actually makes it to the stomach to be digested) or your pup will fail to thrive. Their swallowing can sound “gurgly” and they may cough/be sick due to aspiration pneumonia.

The frequent regurgitation should be a red flag for your veterinarian.

There’s no “test” for megaoesophagus, but the dilated oesophagus can usually be seen on plain chest x-rays. Sometimes your vet will need to use a contrast medium to better visualise the oesophagus.

Further testing may be required to find the underlying cause of the problem (if there is one) and to decide on the best treatment/management protocol.

Can it be treated?

In most cases, the megaoesophagus cannot be treated but only managed. The aim of management is to ensure that enough food does get into the stomach and the rest of the digestive tract (thus preventing your pet from literally starving to death) and to prevent aspiration pneumonia (a common complication).

Your pet will likely need a high-calorie food. The presentation of the food (blenderised gruel or “meatballs” of food) depends on the patient. In some patients, a stomach feeding tube is the only way the megaoesophagus can be “treated”.

The pet should be fed in an upright position, 45-90 degrees to the floor. This position should be maintained for 10-15 minutes after feeding. A Bailey chair (Google has a host of information on how these work and even how to build your own) is designed to keep your pet in that position. You can already imagine how “involved” the simple action of your dog eating its food has suddenly become.

Unfortunately, the outlook for a dog with megaoesophagus isn’t great. The underlying neurological conditions may not be treatable at all and the real risk of aspiration pneumonia is always there.

For those of you who are dealing with a megaoesophagus pet, I hope things are under control and manageable. For all the other fortunate readers, megaoesophagus is a trying condition, and now you’ll know what to expect if it does come your way.



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