Megaesophagus in Dogs

The phrase ‘bigger is better’ doesn’t apply to everything in life, especially when it comes to the body.

The medical term “mega’ comes from the Greek word megas, which means great or big. When “mega’ is applied as a prefix it means abnormally large.

In simple terms, megaesophagus means an abnormally large (dilated) esophagus. Understanding what megaesophagus is will help you improve your dog’s life and decrease potential complications of this condition.

What Is Megaesophagus?

The esophagus is the tube through which food passes from the mouth to the stomach. The passage of food through the esophagus is not a passive process. Rather, it is the result of a neurologic reflex that causes sequential muscle contraction and relaxation that push the food into the stomach once it is identified in the esophagus. This highly active process also includes other reflexes, such as the swallow reflex and the closing off of the airways to prevent food from being inhaled into the lungs.

These reflexes can be disrupted when there is disease of the esophageal tissue or disease of the nerves. When the reflexes are disrupted, the ability to actively move food down the esophagus is lost. Then the esophagus loses tone and dilates (widens).

When the motility is decreased or lost in the esophagus there is an accumulation of food and liquid within it. Following this, there is a disruption in the reflexes that close off the airways, which can result in aspiration pneumonia. Megaesophagus is the term used to describe the soft, lax, and air-filled esophagus that results.

Causes of Megaesophagus

Megaesophagus can be congenital or acquired. Dogs with congenital megaesophagus are born with it whereas those with acquired develop it during adulthood.

Congenital Megaesophagus

Breeds predisposed to congenital megaesophagus include:

• Chinese Shar Peis
• German Shepherds
• Great Danes
• Irish Setters
• Labrador Retrievers
• Miniature Schnauzers (inheritied)
• Newfoundlands
• Wire-haired Fox Terriers (inherited)
  
  

Incomplete nerve development

Incomplete nerve development in the esophagus is believed to be the cause of congenital megaesophagus.

This condition generally involves pups. Though they are believed to be born with it, it isn’t observed until the puppy starts consuming solid food. Typically, the condition is diagnosed around 12 weeks of age but can be later, up to a year of age, for mild cases.

In some cases, as a puppy matures, the nerve development may improve. Some studies indicated a 20–40% recovery rate.

Vascular ring anomaly

A vascular ring anomaly is a band of tissues that are remnants of fetal blood that are supposed to disappear prior to birth. When it doesn’t, it can impact the esophagus. The esophagus is encircled and constricted by the vascular ring anomaly. Solid food is unable to pass through the esophagus resulting in megaesophagus.

Diagnosis for this congenital condition is generally between 2–6 months of age.

The good news is improvement can occur when the band is surgically cut. However, complete resolution of clinical signs only occurs in about 30% of cases.

Dermatomyositis

Dermatomyositis is a disease that causes severe inflammation of the skin, muscles, and blood vessels in the body. 

Since this condition can decrease the muscle tone and function of the esophagus, it can cause megaesophagus.

It is an inherited disease that affects the following breeds or mixes:

• Collies
• Shetland Sheepdogs

Similar signs that are associated with dermatomyositis have also been noted in the following breeds: 

• Chow Chow
• German Shepherd
• Kuvasz
• Lakeland Terrier
• Welsh Corgi

Symptoms of dermatomyositis typically develop before 6 months of age and adult onset is rare.

Skin lesions are generally noted initially. Muscle involvement is variable with some dogs being unaffected versus some suffering generalized muscle atrophy (wasting) and weakness. If facial and chewing muscles are affected, megaesophagus can result.

Acquired Megaesophagus

In adult dogs, there are several potential causes of megaesophagus. In cases where megaesophagus is caused by a disease that can be treated, there can be a significant improvement and potential resolution of the megaesophagus.

Myasthenia gravis

This condition occurs when the immune system destroys the nerve/muscle junctions. It prevents the muscles of the esophagus from receiving signals from the nervous system that coordinate the muscular contractions.

It is the most common cause of megaesophagus and accounts for about 30% of the cases.

Specialized testing is necessary for diagnosis.

The good news is it is a treatable condition.

Stricture

If scarring of the esophagus occurs as a result of a foreign body or prolonged vomiting, there can potentially be a disruption in the neurologic transmission to the esophagus or a narrowing of the esophagus that prevents the passage of food.

Since the muscle of the esophagus is working normally, a stricture (a small area of narrowing) doesn’t cause a ‘true’ megaesophagus despite the fact the esophagus dilates, either prior to or after, depending on the location of the stricture. 

If the stricture remains for an extended period of time, it can result in muscle function damage.

The esophagus can be dilated at the stricture site by a specialized balloon. Despite this, residual regurgitation generally persists and the prognosis is fair to not ideal.

Esophageal obstruction

Like a stricture, an esophageal obstruction can result in megaesophagus. The esophagus can become dilated due to a mass in the chest.

If the obstruction can be relieved, symptoms can be improved.

Hypoadrenocorticism (Addison’s disease)

This condition results when the adrenal glands don’t produce enough cortisol and aldosterone hormones. The carbohydrate metabolism of the esophageal muscle is altered due to the deficiency and in rare cases, megaesophagus can result.

Addison’s disease can easily be diagnosed and is treatable.

Dysautonomia

The condition results when there is total disruption of the entire autonomic nervous system, which controls involuntary bodily functions (heart rate, breathing, digestion).

This condition is found more commonly in these areas:

• Kansas (highest number of cases)
• Missouri
• Eastern Nebraska (Lincoln)
• The eastern half of Wyoming
• Southern Illinois
• Western Kentucky
• Europe

The factors believed to contribute to these areas having a higher incident include:

• They are rural
• Dogs spend more than 50% of their time outdoors
• Dogs have more access to wildlife
• These areas have more pasture land and cattle

Megaesophagus occurs in 60% of dysautonomia dogs. In addition to megaesophagus, dogs with this condition also have megacolon, poor anal tone, poor tear production, difficulty urinating, and dilated pupils.

Diagnosis is done by giving medications that stimulate the autonomic nervous system and observing if there is a response or not. For example, medication can be given that increases the heart rate or causes the pupils to dilate. If these medications do not cause a response, there is dysautonomia.

Recognizing symptoms early is important as the likelihood of successful treatment is poor, and euthanasia is often recommended to avoid suffering.

Some other potential causes of megaesophagus include:

• Laryngeal paralysis

• Systemic lupus erythematosus

• Coonhound paralysis (polyradiculoneuritis)

• Severe esophagitis (inflammation of the esophagus) caused by gastroesophageal reflux, hiatal hernia, or ulcerations caused by tumors or foreign bodies

• Chronic or recurrent gastric dilatation with or without twisting of the intestines (volvulus)

• Degeneration, trauma, or neoplasia of the brain, spinal cord or vagal nerve
  
  

Signs and Symptoms of Megaesophagus

The most common sign of megaesophagus is regurgitation.

Regurgitation is not the same as vomiting. Vomiting is an active process that is associated with heaving, gagging, and retching. Dogs also experience nausea prior to vomiting. Signs of nausea include drooling or licking their lips.

Regurgitation is a passive process. When dogs have megaesophagus, their food and water move through the esophagus as gravity sees fit since there are no coordinated muscular contractions to move it down to the stomach. When your dog lowers their head, the pooled food and water are expelled from the esophagus. Unlike vomiting, there is no heaving, gagging, or retching.

In addition to regurgitation, some other clinical signs include:

• Bad breath

• Signs of aspiration pneumonia (an ongoing issue with megaesophagus)

  • Fever

  • Rapid breathing

  • Abnormal ling sounds

  • Coughing

  • Appetite loss

  • Nasal discharge

  • Lethargy

• Muscle weakness

• Weight loss

• Muscle wasting
  
  

How Is Megaesophagus Diagnosed?

Your veterinarian will obtain a complete medical history about your dog. Be as detailed as possible and provide your veterinarian a video of your dog regurgitating.

After your veterinarian has performed a physical examination, they will recommend chest X-rays. If your dog has megaesophagus, their trachea will be displaced upward in the X-ray and the esophagus will have an accumulation of food, liquid, and gas. Additionally, the X-ray will show any evidence of aspiration pneumonia or masses.

Your veterinarian may recommend other specialized tests, in addition to complete blood count, blood chemistry, and urinalysis, to be sure to rule out all possible causes.

Despite thorough testing, a cause may not be identified. A study found that 76% of cases were idiopathic (unknown cause).

Treatment and Management of Megaesophagus

Dedication and commitment are essential in the treatment and management of megaesophagus.

Congenital megaesophagus can’t be cured but there are ways to manage the condition.

Identifying and treating the cause of acquired megaesophagus can improve or resolve megaesophagus. Some of the causes will require long-term treatment with medications and some, such as obstructions and strictures, require surgery. However, despite treatment, some dogs will still have swallowing issues and regurgitation, so additional management techniques will still be necessary.

Since aspiration pneumonia is often associated with megaesophagus, treatment of it is essential as well. Treatment for aspiration pneumonia involves bronchodilators, expectorants, anti-inflammatory meds, and antibiotics. In some cases, hospitalization for supportive care (oxygen therapy, IV fluids, IV antibiotics, nebulization treatments, coupage, etc.) is necessary.

Management of megaesophagus includes medications, diet alterations, and feeding adjustments.

Medications

For dogs with megaesophagus, the sphincter, between the esophagus and the stomach, which is under control of the autonomic nervous system, is tightly closed. This prevents food from entering the stomach. Therefore, food and liquid remain pooled in the esophagus which results in regurgitation. There is a medication, called Sildenafil, that helps open this sphincter and helps get food out of the esophagus and into the stomach.

There are also medications that stimulate smooth muscle contractions of the gastrointestinal tract. They are referred to as motility modifiers (Metoclopramide and Cisapride). Their purpose isn’t to help move food down the flaccid esophagus but rather to help tighten the lower esophageal sphincter to help keep food in the stomach. For some dogs these medications work well. For others, the sphincter closes before the food gets into the stomach and you end up with the opposite of what you were trying to achieve.

Stomach acid, which can be damaging to the esophagus, is present in the food that moves out of the stomach into the esophagus. This can result in pain, scarring of the esophagus, and possibly causing dogs to be reluctant to swallow. To help minimize the effects of the stomach acid, your veterinarian may prescribe a gastroprotectant medication (Sucralfate).

Antacids are generally avoided because the stomach acid is beneficial if aspiration pneumonia occurs. The stomach acid helps the dog because when it is present in the aspirated material it is less inviting for bacteria.

Studies are looking at using Bethanechol, a promotility agent, to help promote the coordination and contraction strength of the muscles of the esophagus to help move food through the esophagus. It may also help improve the tone of the lower esophageal sphincter.

Diet Alterations

A high-calorie food is often needed for dogs with megaesophagus since they often regurgitate their food, and most are underweight. Discuss with your veterinarian what diet is best and if adding a protein powder, such as whey protein, to your dog’s food would be beneficial.

The consistency of the food is also an important part of managing megaesophagus. Some dogs do better with a solid diet while others a liquid one. Finding what consistency works best for your dog will require some trial and error.

For dogs that struggle with liquids, you will need to find ways to keep them hydrated since drinking water may increase the risk of aspiration pneumonia. You can try giving ice chips, mix a thickener, such as Thick-It Original Thickener, in the water, or give water in gelatin.

Feeding Adjustments

Feeding your dog in an upright or vertical position allows gravity to help move food down the esophagus and lessens regurgitation. They should remain upright following their meal as well. The amount of time they should remain upright after eating will depend on the extent of the megaesophagus and can range from 15 to 45 minutes.

Note: Start with having your dog remain upright for 15 minutes after eating. If they regurgitate, continue to add 5 minutes to the post-meal time until there is no to little regurgitation following a meal.

For smaller dogs, you have different options on how to do this. To keep them upright while feeding, you can place them in a clean, well-padded bucket (2 to 5 gallons), keep them upright on your lap, use a front carrier backpack, or use a specialized chair: You can buy or DIY a Bailey chair (this DIY is less than $20).

To feed medium and large dogs vertically as well as keep them upright after eating, a Bailey chair is the best and easiest option, but if possible you can hold them upright while eating and afterward.

Helping your dog adjust to a Bailey chair

Helping your dog get used to getting into and staying in their chair is very similar to go to place training.

Start by introducing the Bailey chair slowly. Place treats around or inside the chair to make it a positive space. Encourage your dog to investigate it freely, allowing them to sniff and explore the chair without any pressure or commands to do anything.

Once they are familiar, start gently guiding them with a food lure into the chair without securing them. Reward them with treats and lots of praise to reinforce that sitting in the chair is a positive experience. It’s essential to go at your dog’s pace — if they seem hesitant, give them time to build confidence and avoid forcing them in, as that can create negative associations.

Once your dog is comfortable sitting in the chair, gradually increase the time they spend there before releasing them. Begin feeding them in the chair, allowing them to enjoy their meal while seated upright. After each meal, secure them in the chair for about 15 to 20 minutes (severe cases can be up to 45 minutes) to allow gravity to aid in food passage. Stay nearby, offering reassurance, and use calming words to make them feel safe.

With consistency, most dogs will start associating the chair with their meals and positive experiences. It may take time, but with patience and encouragement, they will likely begin to sit comfortably in the chair without resistance. Regular routines, positive reinforcement, and plenty of rewards will ultimately make the Bailey chair a natural and easy part of their daily life.

Gastric feeding tube

Some dogs are unable to obtain enough nutrients even if they are fed a diet of an ideal consistency and are regularly fed in an upright position. In these cases, your veterinarian may recommend a gastric feeding tube.

A gastric feeding tube is a tube that is placed by your veterinarian into your dog’s stomach so food can bypass the esophagus and be delivered directly into the stomach. The tube will exit out the side of your dog’s body and be covered in a protective wrap. Your veterinarian will instruct you on how to blend the food so it can easily pass through the tube, maintain the tube to prevent it from getting clogged, and how to change the bandage.

Having a dog with megaesophagus can feel overwhelming at times. But with some patience, trial and error, as well as support from your vet and canine megaesophagus groups, you can both live a happy life.