New Help for Dogs With Megaesophagus
There’s some exciting, hot-off-the-press news for dogs with megaesophagus. Researchers at the University of Missouri’s College of Veterinary Medicine have new insights about this frustrating and often devastating disease.
What is megaesophagus?
The term megaesophagus refers to weakness, dilation, and decreased motility of the esophagus, the muscular tube that normally propels food, water, and saliva efficiently from the throat down into the stomach. For dogs with megaesophagus, these swallowed materials either remain within the dilated esophagus or are regurgitated back up. Regurgitation resembles vomiting, but unlike vomiting, regurgitation tends to occur without warning. There’s no retching, grazing on grass, or assuming a particular body posture. Regurgitation takes everyone by surprise, including the dog.
As a result of this “surprise factor” the major life-threatening complication for dogs with megaesophagus is aspiration pneumonia. Food material can be readily and inadvertently inhaled into the lungs during a bout of regurgitation. Malnutrition can also be a significant issue for dogs with megaesophagus.
Causes of Megaesophagus
Megaesophagus tends to affect middle aged and older dogs, and there is no breed predilection. Most of the time, an underlying cause can’t be found, and the disease is referred to as, “idiopathic megaesophagus.” Diseases that can cause megaesophagus include:
- Myasthenia gravis: a neuromuscular disease
- Addison’s Disease: a hormonal disorder
- Esophagitis: inflammation of the lining of the esophagus
- Esophageal tumors
- Esophageal foreign bodies
- Esophageal trauma
Treatment of idiopathic megaesophagus revolves around maintaining the dog in an upright position following mealtime so as to allow gravity to help move swallowed food, water, and saliva down into the stomach. The usual recommendation is to maintain the dog in an upright position for approximately 20 minutes following meals. Bailey Chairs (see photo) have been specifically designed for dogs with megaesophagus. They comfortably keep the dog upright and eliminate the need for direct human supervision throughout the process.
A new diagnostic test
New diagnostic testing and treatment described by folks at the University of Missouri College of Veterinary Medicine focus on an anatomical structure called the lower esophageal sphincter (LES). This sphincter acts like a valve between the end of the esophagus and the stomach, opening when food and water are swallowed and then closing so that food is not refluxed from the stomach back into the esophagus.
It turns out that some dogs with megaesophagus have LES dysfunction- their sphincters remain closed, even during the swallowing process. The researchers have been very clever in figuring this out. Using fluoroscopy (a type of video x-ray) they observe the “flight pattern” of swallowed food material as it travels down the esophagus. Such fluoroscopic swallowing studies have been around for a long time, but what’s new about the Missouri technique is how the dogs are restrained. Traditionally, dogs are held on their sides for these swallowing studies, a far cry from how dogs normally position themselves for swallowing. This new research has employed a nifty holding chamber developed to allow the dogs to eat and be restrained for the fluoroscopy in a normal upright position. This technique is providing much more accurate information about esophageal and LES function.
A new treatment
The Mizzou team has fashioned their treatment protocol for dogs with LES dysfunction after what is being done in human medicine. Using endoscopy, in which a long video telescope device is inserted into the esophagus, the LES is manually expanded via a technique called balloon dilation. Next, Botox is injected into the LES. This chemical paralyzes the sphincter muscles, allowing the LES to remain open. Thus far, some of the treated dogs have shown marked improvement. As Dr. James Schachtel, a member of the research team has stated,
This approach gives these dogs a chance, whereas a lot of them didn’t have much of one. At this time, it is early in the evaluation process, but it’s a novel approach that shows promise. This subpopulation can receive a really significant benefit from our direct ability to detect their malady. It can give them a really good quality of life. This is a revolutionary diagnostic technique for a disorder identified with a pathological outcome. It offers us the opportunity to use therapies that have been successful in people, so we’re optimistic we can experience similar success with canines.
While not all dogs with megaesophagus are candidates for this therapy, it is wonderfully refreshing to finally have a new strategy to treat this frustrating disease.
Do you have a dog with megaesophagus? If so, what has your experience been like? The University of Missouri team encourages veterinarians, pet owners and breeders to contact them about their megaesophagus testing and treatment protocol. You can do so by calling the Small Animal Hospital at 573-882-7821.
Nancy Kay, DVM
Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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