Megaesophagus in Canines & Felines – What Is It & How It Affects Your Pet’s Health

October 12, 2017 /

There are many things that can emerge from your pet’s mouth, but what is actually seen coming out of the mouth and the underlying causes can be quite variable.

From saliva (“drool” or ptyalism) to food to color-tinged fluid to the unrecognizable, what your dog orally evacuates can take on many different appearances and create varying levels of concern. One relatively-uncommon health concern leading to ingesta (food, liquid, etc.) erupting from a pet’s mouth is Megaesophagus.

What is Canine or Feline Megaesophagus?

Megaesophagus is a condition affecting pets where the esophagus (“food tube”) stretches beyond its normal capacity and limits the ability of food, liquids, and other substances to properly enter the stomach. Normally, ingesta enters the mouth, is swallowed via the complex mechanism of the larynx (“voice box”), then travels through the esophagus to reach the stomach. Swallowing is a voluntary action, but once ingesta moves beyond the mouth and into the esophagus, involuntary muscular control takes over to push ingesta in a head-to-tail direction towards the stomach. A ring of muscle (esophageal sphincter) at the end of the esophagus controls the flow of contents into the stomach. The involuntary nature of this process takes the thinking out of eating for our companion canines and felines, who simply bite, chew, and swallow as part of their day-to-day survival activities. With Megaesophagus, ingesta collects in the stretched-out esophagus instead of properly moving into the stomach. Once enough ingesta accumulates it finds the point of least resistance and erupts back out through the mouth.

What Are the Causes of Megaesophagus in Canines and Felines?

There are many potential causes of Megaesophagus, which can be can be congenital (inherited) or acquired. Congenital Megaesophagus commonly occurs around the time of weaning (transitioning off of drinking mother’s milk and onto eating solid food) and is suspected to occur as a result of improper esophageal nerve development. As the pet matures, improved nervous system development and esophageal function can occur. Some cases of Congenital Megaesophagus are due to a vascular ring anomaly called a Persistent Right Aortic Arch (PRAA), where a remnant of fetal blood vessels remains and constricts the esophagus. Certain breeds of dog are more prone to Congenital Megaesophagus, including German Shepherds, Great Danes, Irish Setters, Labrador Retrievers, Newfoundlands and Shar-Peis. Irrespective of breed, large dogs are more commonly affected than small dogs. Megaesophagus is diagnosed in both dogs and cats, but dogs are more-commonly affected. Congenital Megaesophagus is generally diagnosed in dogs around 12 weeks of age, which is around the time that puppies are eating solid food after being weaned from a diet of predominantly mother’s milk. Acquired Megaesophagus develops over years of life, generally affects adult and senior dogs ranging in age from five to twelve years, and can have many causes. Idiopathic Megaesophagus occurs when the cause is unknown and is the most-common variety affecting dogs. Generally, Acquired Megaesophagus is considered idiopathic. Acquired Megaesophagus can be caused by ailments that affect esophageal function including:

Dysautonomia—a nervous system abnormality affecting contraction of involuntary muscles, which fortunately is uncommon.
Hypoadrenocorticism (Addison's disease)—an adrenal gland abnormality where improper production of corticosteroids (hormones that manage inflammation and immune system function) and mineralocorticoids (water-regulating hormones) negatively affects the ability of esophageal muscles to contract.
Obstruction—When foreign material or a mass-like lesion (cancer, granuloma, other) takes up space in the esophagus it can prevent proper movement of fluid and food.
Stricture—The esophagus is prone to scarring from consumption of caustic chemicals, foreign material, gastric acid, and process of resolving obstruction (surgical, endoscopic, etc.). Stricture causes reduced esophageal diameter and function, so ingesta builds up in the esophagus and is ultimately regurgitated.

What are the Clinical Signs of Megaesophagus in Dogs and Cats?

When food or liquid erupts from a pet’s mouth it can happen during an active or passive process. Differentiating between vomiting and regurgitation is an important part of diagnosing Megaesophagus. Vomiting is an active process where muscular contraction occurs in the stomach and abdominal wall musculature forces stomach contents up the esophagus and out through the mouth. Regurgitation is a passive process lacking muscular contraction where the contents of the esophagus and stomach seemingly pour out of the mouth. Regurgitation is generally gravity-dependent and will occur when a pet is standing or when the head drops below the level of the body (thereby creating an easy path through which ingesta flows). Patients having Megaesophagus generally exhibit regurgitation instead of vomiting. Megaesophagus causes many secondary health problems, including:

Pneumonia—Regurgitation caused by Megaesophagus leads to food and liquid being inhaled (aspirated) into the respiratory tract as it exits the body, which in turn causes aspiration pneumonia.
Lethargy—Many patients having Megaesophagus chronically don’t feel their best, in part due to nutrients and liquid being improperly absorbed from the digestive tract and secondary health problems like pneumonia.
Increased respiratory rate/effort—Pets will breathe faster when ingesta collects in the esophagus and takes up space in the thoracic (chest) cavity that's otherwise occupied by the lungs. If the lungs are kept from properly expanding or if pneumonia occurs then increased respiratory rate and effort occur. Besides seeing your pet’s chest move in and out at a faster pace there can be an abdominal component to breathing due to the diaphragm’s increased effort to get oxygen-rich air into the body.
Cough—In attempt to clear regurgitated ingesta from the respiratory tract and throat, Megaesophagus patients will cough. The cough typically sounds moist and can be productive, where food, fluid, mucus, or other substances are evacuated with each forceful ejection of air.
Weight loss—If food and liquid don’t properly move from the esophagus into the stomach then the small intestines won’t receive crucial nutrients and body mass cannot be sustained.

How is Megaesophagus Diagnosed in Canines and Felines?

Besides the clinical signs of regurgitation, diagnostic testing is important in diagnosing Megaesophagus. Radiographs (x-rays)—The esophagus courses through the thoracic cavity to reach the stomach, so chest radiographs can reveal accumulation of ingesta in the esophagus in front of the diaphragm (thin band muscle that separates the chest cavity from the abdominal cavity). Sometimes contrast radiograph with water-soluble contrast agents is needed to delineate the distended esophagus. Barium should not be used as contrast agent with suspected cases of Megaesophagus as it can cause deadlier aspiration pneumonia as compared to that associated with inhaling water, food, or water-soluble contrast agents. Changes in lung pattern consistent with pneumonia may also be seen with Megaesophagus patients. Aspiration pneumonia has a distinct appearance on radiographs where gravity causes ingesta to accumulate in lungs at bottom and middle lobes. Radiographic examples of the normal canine chest vs. one having Megaesophagus can be seen via Veterinary Partner. Blood and Urine Testing—Baseline organ function must be evaluated to look for abnormalities in the kidneys, liver, pancreas, electrolytes, blood proteins, red and white blood cells, platelets, thyroid glands, and more. Conditions like Hypoadrenocorticism can be revealed through blood testing. Although Megaesophagus does not directly affect kidney health, urine testing is another crucial part of measuring hydration and the ability for organs to tolerate certain medications. Endoscopy—Visualizing the inside of the esophagus is an essential part of determining potential underlying causes for Megaesophagus. Endoscopy involves the use of a fiberoptic scope placed into an anesthetized patient’s esophagus to attain a through visual assessment, take tissue samples for biopsy, or relieve/remove obstructions. Endoscopy also permits assessment of the larynx, which is a complicated series of parts functioning to protect the airway when food and liquid are swallowed. Laryngeal paralysis can cause signs similar to and occur in association with Megaesophagus.

How is Megaesophagus Treated in Dogs and Cats?

Part of the challenge of treating Megaesophagus is striving to resolve the issue when there may be no known cause (idiopathic). Congenital Megaesophagus caused by vascular ring anomaly (PRAA) can be surgically resolved. Congenital Megaesophagus generally holds a better prognosis than acquired Megaesophagus. Acquired Megaesophagus can potentially be cured if the underlying cause is identified and resolved. Hypoadrenocorticism and esophageal obstruction have a greater resolution rate as compared to Myasthenia gravis, obstruction, stricture, and dysautonomia. If Megaesophagus cannot be resolved then veterinarians and owners must come together to manage the condition and give the pet the best possible quality of life. Such is commonly the goal for many patients suffering from the condition. Management involves lifestyle changes like: Dietary modification—Feeding a moist diet having soft to liquid consistency is the general recommendation for dogs suffering from Megaesophagus. Solid foods like kibble or chunks of fresh foods are more likely to accumulate in the esophagus. Since Megaesophagus patients also have problems drinking, it’s best that food is moist to liquid in consistency to provide hydration. Foods from The Honest Kitchen are ideal for pets with Megaesophagus due to its soft consistency and its ability to hydrate. To see how other pets with Megaesophagus have benefited from a diet of Honest Kitchen, click here. Feeding from an elevation—As a means of reducing regurgitation, having the patient eat in a position where the mouth is elevated to a 45 to 90 degree angle above the hindquarters of the body is important. This way ingesta will move with gravity down the esophagus toward the stomach and not remain in a position where regurgitation can easily occur. Patients must eat slowly and be kept in this upright position for 15 minutes or more after each meal. Some dogs can be fitted to a home-prepared or commercially-available device called a Bailey chair. Bailey is the name of a dog who suffered from Megaesophagus and his owners created a chair-like device to help him comfortably eat from an elevated position. BaileyChairs4Dogs.com is a great resource for owners interested in learning about or purchasing a Bailey Chair. If feeding from an elevated height or Bailey Chair fails then the patient can be anesthetized and have a Percutaneous Endoscopic Gastrostomy (PEG) tube placed to allow the owner to bypass the esophagus and give feeding directly into the stomach. Medications—There’s no single medication that can help patients affected by Megaesophagus, so the treatment goal is to go manage associated clinical signs and enhance and protect the digestive tract. Motility modifiers like Metoclopramide (Reglan) and Cisapride (Propulsid) are drugs that enhance the movement of the stomach and intestinal contents by promoting smooth muscle contraction and can have an anti-nausea effect. Gastroprotectants do as their name describes and protect the digestive tract from inflammation and damage and include medication like Sucralfate (Carafate), which has an effect to soothe the irritated stomach and intestinal tissue. The use of antacids like Famotidine (Pepcid), Ranitidine (Zantac), Cimetidine (Tagamet), Omeprazole (Prilosec), and others is controversial, as reduced stomach acid can lead to less irritation of esophageal tissue upon vomiting (but not regurgitation). Yet, weaker stomach acid is less likely to kill bacteria and could encourage bacterial aspiration pneumonia. Novel treatments for Megaesophagus include plasmapheresis (plasma exchange), where blood is removed from the body and cleansed of toxins and immune system factors that can trigger an immune system response that negatively affects nervous systems functions like involuntary muscular contraction of the esophagus. The patient’s own plasma (a blood component lacking red blood cells) is then transfused. Supplements—Probiotics are beneficial bacteria that help to keep a balance between other beneficial bacteria that naturally exist in the small and large intestine and pathogenic (disease-causing) bacteria. Prebiotics provide the substances on which probiotics grow to aid in optimal digestion and can come from supplements containing Fructooligosaccharides (FOS), Inulin, and others and diets having whole grains, fruits, and vegetable fiber. Other fiber sources like pumpkin (canned or cooked fresh) and psyllium husk can help foster the presence of probiotic bacteria in the gut and enhance stool firmness. Aloe leaf extract, ginger, and licorice root have properties to soothe upset stomach and intestines. Glutamine, an amino acid that nourishes intestinal cells, and papain, a protein-digesting enzyme (from papaya), can promote better digestive tract function. Ginger and turmeric are roots that have natural anti-inflammatory effects on the gut and other body systems. The Honest Kitchen’s Instant Goat's Milk is shelf-stable goat’s milk that contains 5 billion active probiotics and digestive enzymes. The Honest Kitchen’s Perfect Form is a digestive supplement that’s ideal for cats and dogs with gastrointestinal upset and less-than-perfect digestion. As each case of Megaesophagus is different, the regimen of feeding, medications, and supplements must be individually tailored to the patient’s particular needs. On-line resources are available to owners of dogs with Megaesophagus, include:

Can Megaesophagus Be Prevented in Canines and Felines?

Dogs that have optimally functioning digestive tracts are generally less-prone to a variety of ailments as the immune system and digestion are highly correlated. When vomiting and diarrhea are frequent the associated inflammation can negatively impact normal function and overall health of digestion and other body systems. Of course, prevention is the best medicine and some forms of Megaesophagus can be prevented. When it comes to Congenital Megaesophagus, patients known to have the condition should not pass on their genetics to further generations and should be excluded from breeding stock and be spayed/neutered. Preventive measures for Acquired Megaesophagus are targeted at minimizing damage to the esophagus to reduce the likelihood of obstruction and stricture. When stomach acid enters the esophagus irritation occurs, which over time leads to scarring, reduced function, and potential development of Acquired Megaesophagus. Additionally, many cats and dogs are prone to dietary indiscretion where substances from their indoor or outdoor environments like fabrics, hair, rocks, plants, plastic, soil, and other materials are ingested. Pets having dietary indiscretion are more prone to vomiting and stool changes, which can play a part in Acquired Megaesophagus development. In my experience, patients eating diets and treats that are whole food-based are less prone to digestive tract upset and acquired Megaesophagus. Additionally, when the feeding style is similar from meal to meal (i.e. each meal contains similar protein sources and the format doesn’t vary from canned to dry to fresh to raw or other varying combination) digestion and bowel movements are more consistent and vomiting is minimized. Having your pet examined by a veterinarian at least every 12 months and performing recommended diagnostic testing can help detect Megaesophagus and associated ailments before the conditions become severe and potentially untreatable. Has your pet ever been diagnosed with Megaesophagus? Feel free to share your experiences in the below Comments section.

Interested in seeing the impact of diet on pets with Megaesophagus? Read through our True Stories here.

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