By Dr. Becker
Today I'd like to discuss megaesophagus, which means "big esophagus." It's a condition in which the esophagus, a muscular tube from the mouth to the stomach, is enlarged and malfunctioning. Both dogs and cats can develop the disorder, but it's much more common in dogs.
What Megaesophagus Is
When food or liquid is swallowed, it travels through the esophagus, which is designed to expand and contract rhythmically to move foods and liquids to the stomach. When the esophagus is functioning as it should, food moves from the mouth to the stomach within seconds.
In megaesophagus, there are issues with nerve and muscle functioning that cause a motility problem. The esophagus stretches out and muscular contractions aren't efficient. As a result, food doesn't always reach the stomach. It can build up in the esophagus, which eventually will cause the dog to regurgitate.
Regurgitation can occur within minutes of swallowing food, in which case the food looks exactly as it did going in. If regurgitation occurs hours after eating, the food reappears in a tubular or sausage shape.
Constant regurgitation predisposes animals to aspiration pneumonia, which occurs when a dog inhales during an episode of regurgitation, bringing food into the lungs. This can cause a terrible, potentially life-threatening infection.
Causes of Megaesophagus
Megaesophagus varies in terms of severity. There can be a mild motility problem in just one area, or the entire tube can be enlarged and functioning poorly. Megaesophagus can be congenital, which means present from birth, or acquired.
Congenital megaesophagus is more common than the acquired form, and certain breeds of dogs are predisposed including the Fox Terrier, German Shepherd, Great Dane, Irish Setter, Labrador Retriever, Miniature Schnauzer, the Newfoundland, and the Shar-pei.
Megaesophagus in cats is uncommon, but when it does occur, Siamese and related breeds seem to be predisposed.
The acquired form of this condition usually occurs in older pets and is almost always secondary to certain other conditions including autoimmune neuromuscular disease, Addison's disease, and hypothyroidism. It can also be caused by a problem in the esophagus like a foreign body, inflammation, or a tumor, as well as by exposure to toxins including organophosphates.
In acquired megaesophagus, it's crucial that an underlying cause be identified and treated, if possible, in order to cure or control the condition.
In some cases, no cause for the disorder can be found and it is determined to be idiopathic, meaning we don't know why it's happening.
Symptoms and Diagnosis
Symptoms of megaesophagus include regurgitation of food and water. Remember, regurgitation is different from vomiting. Vomiting is an active process where your dog's sides start to heave and most or all of her stomach contents are purged. Often with vomiting, there's a short window of time during which you can get your dog outside before she throws up.
Regurgitation is very different. It's a passive and unexpected act. Your dog's just kind of hanging out and in a split second, up comes food.
Other symptoms of megaesophagus related to the loss of calories from regurgitation or secondary pneumonia include difficulty swallowing, excessive salivation, coughing, a change in vocal tone, nasal discharge, bad breath, fever, weight loss, extreme hunger, poor body condition, and respiratory distress.
Puppies with congenital megaesophagus typically begin regurgitating as soon as they begin to eat solid food.
A dog with suspected megaesophagus should be seen promptly by a veterinarian for a thorough examination. Megaesophagus can be fatal, especially if aspiration pneumonia develops secondarily to the condition.
Your vet will take a thorough history and pay particular attention to the symptoms your dog has displayed. Blood work will be performed, and x-rays of the chest and abdomen will also be necessary to check for an enlarged esophagus that may contain air, fluid, or food.
A definitive diagnosis is usually made with either a barium study of the esophagus or fluoroscopy. A more advanced technique called esophagoscopy can sometimes be used. This is a procedure that allows visualization of the interior of the esophagus and can also be used to remove a foreign body if found or to evaluate any obstructions or tumors that are discovered.
Depending on your pet's age and symptoms, other blood tests might include an acetylcholine receptor antibody test, antinuclear antibody test, which is called an ANA titer for immune-mediated diseases, and hormonal testing such as an adrenal stimulation test and thyroid function testing.
Treatment and Supportive Care
If the megaesophagus is acquired and secondary to an underlying disease, that problem must be identified and resolved if at all possible.
In cases of congenital or acquired idiopathic megaesophagus, treatment is focused on symptom management and supportive care. There are a few drugs that are sometimes used in pets with megaesophagus, but they aren't routinely effective and have significant side effects, as a lot of medications do.
Eating and drinking obviously pose the biggest threat to pets with megaesophagus, because these are the activities that prompt episodes of regurgitation, which is what leads to lack of nutrients and aspiration pneumonia.
Pets with megaesophagus tend to do better with small, frequent meals fed out of elevated food bowls or by hand, with the head in an elevated position. With the body elevated, which means in a vertical position, gravity can do some of what the esophagus isn't doing.
Many owners of dogs with megaesophagus encourage their dogs to hold a sit position for 10 minutes after eating or drinking anything, to allow the food and water to eventually reach the stomach with the effect of gravity.
Some pet owners use a "Bailey Chair," which is a piece of equipment that functions like a high chair for dogs, keeping them in an upright position during meals. You can maintain a dog in the Bailey chair for 10 to 30 minutes after a meal, allowing gravity to move the food down the esophagus and into the stomach.
Many veterinarians also recommend thickening agents be added to water to reduce the likelihood of recurrent aspiration episodes. Finding the best form of food to feed and method for feeding it is usually mastered through trial and error.
Acupuncture can sometimes be used to stimulate esophageal motility, and chiropractic care may help remove disruptions to the nerves in the esophagus. There are some traditional Chinese medicinals and also homeopathics that have been used to stimulate esophageal tone, as well as nutraceuticals such as choline and whole food organic minerals that have proved to be somewhat beneficial for the megaesophagus patient.
Managing a dog with megaesophagus is obviously time-consuming. But with the proper care, many pets live relatively normal lives with a disorder that used to be fatal in most cases.