In a person, the esophagus is vertical. That means that in addition to muscle contractions in that organ propelling food from the back of the mouth to the stomach, gravity helps the food slide down. A dog’s esophagus, on the other hand, is horizontal. So if it doesn’t work right, food doesn’t make its way through the digestive tract. A dog will end up regurgitating much of his meals. Often, aspiration pneumonia sets in when the food erroneously ends up in the dog’s lungs or airway. There can also be severe malnourishment that leads to an inability to thrive and, all too often, death.
The malfunctioning of a dog’s esophagus is frequently due to a condition called megaesophagus. It’s a dilation of the esophagus resulting from faulty wiring, so to speak. Something goes wrong in the nerve impulses that instruct the muscles to contract, and the esophagus loses its tone and literally enlarges. (Thus, the term “mega.”)
In some dogs, megaesophagus is a congenital disease. Among the breeds predisposed to being born with it: Great Danes, Irish setters, Newfoundlands, German shepherds, shar peis, and Labrador retrievers. Others develop it in adulthood.
In most cases, the disease is either present at birth or comes on idiopathically, meaning no cause can be found. But about 25 percent of the time, megaesophagus develops as a result of another condition, says Michael Stone, DVM, a veterinary internist at Tufts and a member of the Your Dog editorial board. One of those conditions is myasthenia gravis, which is a breakdown in the communication between the nerves and the muscles. Another is Addison’s disease, in which the metabolism of the esophageal muscle becomes altered in a way that doesn’t allow the muscle to function properly.
Diagnosis, treatment, and prognosis
“Many things look like megaesophagus but aren’t,” Dr. Stone says. For instance, a puppy may be born with a vascular ring that encircles the esophagus, not allowing food to move properly. Some obstructions can be removed surgically, and the esophageal dilation may improve. That’s important, the doctor says, because sometimes a breeder will euthanize a pup thinking he has megaesophagus, which can’t be cured, when it’s a different problem altogether. It’s critical to get a medical diagnosis rather than decide based entirely on symptoms. The workup will involve x-rays and perhaps other tests as well.
A diagnosis of megaesophagus that is found to result from another disease is a best-case scenario. Once that other disease is diagnosed and medically treated, the esophageal dilation may completely resolve.
Otherwise, “prognosis is very guarded,” says Dr. Stone. In some cases, a dog diagnosed with congenital megaesophagus simply grows out of the condition. “That’s rare, but I have seen it,” Dr. Stone says. In most others, and with adults diagnosed with idiopathic megaesophagus, there’s lifelong management. For whatever reason, there has been nerve degeneration from the brain down to the esophagus, and there’s no fixing it. There’s only trying to help the dog live with it.
Some people feed their dog sitting up in what is known as a Bailey chair, which looks something like a high chair. It forces the dog’s throat to tilt vertically, which allows more of a gravitational influence. The dog stays in the chair for 10 to 15 minutes after eating. Meals have to be mixed just so, too, with a food-to-water ratio that works best for that particular dog. These strategies might help, Dr. Stone emphasizes. They don’t always.
Sometimes a feeding tube is inserted directly into the stomach in order to bypass the esophagus completely. For people who want to be able to continue to feed their dogs by mouth, medication may be of use. There are essentially two kinds that have been tried. One is called metoclopramide, which helps close the sphincter muscle between the esophagus and the stomach so that any food that does make it to the stomach doesn’t come back up. The other is sildenafil, which is the generic name of Viagra. It can help food move from the esophagus into the stomach.
Neither is foolproof; “it’s all trial and error,” Dr. Stone comments. One drug might work for some dogs and not others. Some dogs might benefit from both. Others might benefit for a while and then not. And some dogs actually end up worse from the medications. Moreover, neither is completely effective. “Megaesophagus is not like an infection for which you give antibiotics and the dog is all better,” Dr. Stone says. “Regurgitations may go from six times a day to a day.” A dog can still end up with aspiration pneumonia, malnourishment, or some other complication.
You may be able to help a struggling dog manage to live at least a few years, Dr. Stone says, but it depends on the time commitment you can make along with your financial resources.
We get about a half dozen cases at Tufts each year, he notes. There are many more than that number would suggest, he says, but people will often euthanize a puppy with megaesophagus, so it’s difficult to pull together reliable statistics.
