Megaesophagus
What is Megaesophagus (ME) ?
Megaesophagus is a condition in which the tube carrying food from mouth to stomach is too big and doesn't work properly. A normal esophagus has muscles that move the food into the stomach and help keep it there. The esophagus in an ME dog does not have these reflexes to push the food down into the stomach. The food will “pool” in the esophagus and stretch it. The stretching leads to damage to the nerves.
Other reflexes of a normal esophagus prevent breathing during swallowing so that food and liquids cannot be inhaled into the lungs. The other danger with ME is that food moving in the wrong direction during regurgitation can enter the trachea and lungs. This results in aspiration pneumonia, which is the most common reason dogs die from this disease.
Symptoms of ME:
What causes ME?
How is ME diagnosed?
The typically diagnostic work-up for megaesphagus begins with chest x-rays. X-rays may show the esophagus dilated with food and will determine whether or not there is secondary aspiration pnuemonia. In some cases, the nature of the ingested material does not allow for visualization of a dilated esophagus. If the history fits mega-esophagus, but a dilated esophagus is not seen on routine x-rays, then a contrast study can be performed, where prior to the x-ray, a radio-opaque liquid is swallowed. Since the liquid will show brightly on the x-ray, the integrity and shape of the esophagus will be clearly visualized.
A routine blood panel should also be run, consisting of a CBC, chemistry, and a thyroid profile (TSH, T4, free T4). A test for myesthenia gravis (acetyl choline receptor antibody test) should also be run.
The majority of cases of canine megaesophagus have no apparent cause. A minority of cases are caused secondary to underlying disease, typically hypothyroidism or mysthenia gravis.
Megaesophagus is a condition in which the tube carrying food from mouth to stomach is too big and doesn't work properly. A normal esophagus has muscles that move the food into the stomach and help keep it there. The esophagus in an ME dog does not have these reflexes to push the food down into the stomach. The food will “pool” in the esophagus and stretch it. The stretching leads to damage to the nerves.
Other reflexes of a normal esophagus prevent breathing during swallowing so that food and liquids cannot be inhaled into the lungs. The other danger with ME is that food moving in the wrong direction during regurgitation can enter the trachea and lungs. This results in aspiration pneumonia, which is the most common reason dogs die from this disease.
Symptoms of ME:
- Regurgitation
- Regurgitation is different than vomiting. Vomiting is when the body actively pushes contents out of the stomach. Regurgitation is when food or liquid falls out of the mouth or throat.
- Weight Loss
- Because food does not reach the stomach, the dog is not getting adequate nutrition.
- Extreme hunger or lack of appetite
- Halitosis (Bad Breath)
- Aspiration Pneumonia
- Aspiration pneumonia can occur when food sitting in the esophagus is inhaled into the lungs. The symptoms of aspiration pneumonia include difficulty breathing, difficulty swallowing, coughing, nasal discharge, fever, increased heart rate, weakness, lethargy, and a bluish tint to the skin.
What causes ME?
- Congenital
- Initial symptoms may be seen while nursing, but sometimes they are not seen until a puppy is transitioned from maternal milk to dog food. Then symptoms of regurgitation and secondary pneumonia are noted
- There is no surgical treatment for this type of megaesophagus; it can be managed with a variety of life-style changes. These include feeding and watering in an upright position (using a Bailey chair) with small, frequent, calorically dense meals. Some dogs do better with slurry/gruel while others thrive on meatballs. It will depend on each dog’s ability to swallow.
- Initial symptoms may be seen while nursing, but sometimes they are not seen until a puppy is transitioned from maternal milk to dog food. Then symptoms of regurgitation and secondary pneumonia are noted
- Secondary
- The list of underlying causes for acquired megaesophagus is extremely long and includes muscle diseases like polymyositis, infectious disease such as tetanus, Addison’s disease, cancer, myasthenia gravis, toxins including lead and thallium, and trauma.
- myasthenia gravis
- One of the most common causes of ME in older dogs. This is a systemic, autoimmune illness in which the body’s immune system destroys important receptors in nerve endings. It results in generalized weakness, particularly worse after exercise. There is a medication to treat MG, and it can improve the motility of the esophagus.
- persistent right aortic arch (PRAA)
- When a dog is born, that extra blood vessel causes constriction as the esophagus passes through the chest. In front of the vessel, the esophagus is dilated. As a puppy starts to eat dog food, it becomes trapped in the area, dilating the esophagus.
- This IS a fixable condition with surgery. However, after surgical repair, hypomotility may persist due to esophageal damage. Rapid diagnosis and treatment are essential to a good outcome. Any puppy that develops regurgitation at weaning should be immediately evaluated. X-rays with and without contrast can be done to diagnose this condition. If a persistent vascular ring anomaly is diagnosed, surgery can be done to snip the extra vessel. This is generally conducted by a board-certified surgeon, but there are general practitioners who have performed this surgery as well
- When a dog is born, that extra blood vessel causes constriction as the esophagus passes through the chest. In front of the vessel, the esophagus is dilated. As a puppy starts to eat dog food, it becomes trapped in the area, dilating the esophagus.
- myasthenia gravis
- The list of underlying causes for acquired megaesophagus is extremely long and includes muscle diseases like polymyositis, infectious disease such as tetanus, Addison’s disease, cancer, myasthenia gravis, toxins including lead and thallium, and trauma.
How is ME diagnosed?
The typically diagnostic work-up for megaesphagus begins with chest x-rays. X-rays may show the esophagus dilated with food and will determine whether or not there is secondary aspiration pnuemonia. In some cases, the nature of the ingested material does not allow for visualization of a dilated esophagus. If the history fits mega-esophagus, but a dilated esophagus is not seen on routine x-rays, then a contrast study can be performed, where prior to the x-ray, a radio-opaque liquid is swallowed. Since the liquid will show brightly on the x-ray, the integrity and shape of the esophagus will be clearly visualized.
A routine blood panel should also be run, consisting of a CBC, chemistry, and a thyroid profile (TSH, T4, free T4). A test for myesthenia gravis (acetyl choline receptor antibody test) should also be run.
The majority of cases of canine megaesophagus have no apparent cause. A minority of cases are caused secondary to underlying disease, typically hypothyroidism or mysthenia gravis.
What is the treatment for ME?
Megaesophagus can be difficult to treat, and the general approach is to manage the condition through lifestyle changes. Some puppies with congenital megaesophagus may outgrow the condition, and surgery may be possible for certain development abnormalities.
However acquired cases of megaesophagus, cannot be reversed. For these dogs, treatment is essentially supportive, and may include:
- Treating respiratory infections with antibiotics as soon as they occur.
- Managing your dog’s eating and assuring that nutritional needs are met.
Several strategies to control the regurgitation of food are typically employed:
- Feeding from an elevated position to facilitate downward movement of food. Many pet parents use a Bailey chair or a padded laundry hamper to keep the dog upright. For larger breed dogs, such as Danes, using a staircase or ladder to elevate the dog’s bowl can be helpful.
- Diet consistency:
- Some dogs do well on slurry consistency food, such as The Honest Kitchen.
- I've found most success with meatballs. We use Steve's, Tucker's, Kure, or Answers Fermented Raw Pet Food rolled into meatballs.
- Maintaining elevation of the body after eating- the time can vary but usually 15-20 min is sufficient.
- Esophageal tube feeding or surgical stomach tube placement for dogs is an option for dogs who are are critical and unable to eat on their own.
- Medications:
- A study in 2017 showed some improvement in dogs with idiopathic/congenital megaesophagus when treated with sildenafil (Viagra). There is currently more research going on now for this drug. Two of our three ME dogs use Sildanfil with great success.
- Metoclopramide can help to increase muscle tone around the esophagus and stimulate contractions.
- Antacids are typically prescribed by traditionally trained vets as they can help to reduce esophageal damage. We saw an increase in regurgitation in all three dogs while on antacids. We generally discourage their use in dogs, as there are more holistic options available with fewer side effects (such as Bao He Wan)
- Bao He Wan is a Chinese herb that helps with food stagnation.
Preventing megaesophagus comes down to removing affected individuals from breeding programs, regardless of the cause of the disease. Their siblings and parents should also be tested for the disease underlying the megaesophagus before they are allowed to continue or enter breeding programs.