The esophagus is a muscular tube that connects the back of the throat to the stomach for the passage of food.
The esophagus is designed to milk food down toward the direction of the stomach.
In megaesophagus, though, the tube develops a pouch in which food can sit and be delayed on the downward journey. If the dog puts his head down, then, the food is likely to be regurgitated under the influence of gravity.
- Dogs may be born with megaesophagus, in which case they show signs at a very young age.
- Alternatively, the problem may be acquired later in life as a result of a physical blockage or because of certain diseases.
Signs directly related to having a megaesophagus include difficulty swallowing and food regurgitation.
The regurgitated food often comes back up in a sausage shape (matching the esophageal pouch), and because it has not been in contact with stomach acids, it is undigested. This also means that affected dogs may not benefit from any calorie intake and are often skinny or in poor body condition.
Another set of symptoms of megaesophagus in dogs relates to the knock-on effect of regurgitation, and this is an increased risk of aspiration pneumonia. Because food “falls” back into the mouth under gravity, if the dog breathes in at the wrong moment, he may inhale food into his windpipe and down into his lungs. This material irritates the lung tissue and is likely to set up pneumonia with symptoms of coughing, fever, lethargy and loss of appetite.
Don’t Miss: Caring for a Dog With Megaesophagus
Some puppies are born with a pouch in their esophagus — these dogs may have difficulty feeding right from the start.
More common are dogs with an anatomical defect that narrows the exit of the esophagus and makes it difficult to pass. This causes a logjam of food upstream, and in time, the muscles of the esophagus weaken and become baggy, and then a pouch forms.
Of these anatomical problems a persistent right aortic arch (especially in German Shepherds) is one of those more frequently found. In this case, a vascular band encloses the esophagus, a bit like putting a tight rubber band around a tube, and stops food from entering the stomach.
There are unfortunate examples of dogs eating things like hot potatoes that burn the esophagus on the way down and the resulting scar tissues causes a stricture, which then causes a pouch.
The final group of dogs that can acquire megaesophagus is that suffering from diseases such as botulism, myasthenia gravis or Addison’s disease, where neurological messages to the esophagus are lacking and the muscles fail to milk food down into the stomach.
The veterinarian will have a strong suspicion of megaesophagus from a history of regular regurgitation of undigested food.
To confirm the diagnosis is a relatively simple matter of giving the dog a small volume of barium to drink and then taking a radiograph to see where the barium ends up. If a dilated esophagus is present, the barium nicely outlines the distended esophageal walls.
The next step is to look for underlying factors, such as a persistent right aortic arch, or health issues, such as Addison’s disease. This may require targeted blood tests, an ultrasound scan or MRI imaging.
Unless there is a physical factor that can be surgically corrected, such as ligating the persistent right aortic arch, it is not possible to correct the physical abnormality of a dilated esophagus. If, however, the problem is caused by a medical condition, such as Addison’s disease, treating that problem usually helps.
A big part of helping dogs with megaesophagus is to feed them from a raised bowl to get gravity to work with, rather than against, the body. Some people report that feeding their dogs by hand also helps, presumably because it takes longer for the pet to eat, which gives the food longer to go down between swallows.
Another factor to consider is being vigilant for aspiration pneumonia and giving courses of antibiotics to settle the infection.
Except for dogs who eat hot potatoes, it is impossible to prevent the causes of megaesophagus.
- “Management of megaesophagus in the dog.” Simpson. In Practice, 16: 14–16.
- “Risk factors for acquired megaesophagus in dogs.” Gaynor, Shofer & Washabau. JAVMA, 211: 1406–1412.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 13, 2018.