Megaesophagus is a serious problem in dogs that affects their ability to swallow and keep food down. Special measures need to be taken by a dog owner to ensure a dog with megaesophagus is still able to eat and retain its food or this issue can be fatal due to side effects of the disease process.
What Is Megaesophagus in Dogs?
Megaesophagus is also known as dilatation of the esophagus or "Mega E" and describes an enlarged or widened esophagus with decreased motility. Normally the esophagus is a smooth, thin muscle lined with mucosa that gently helps food slide down into the stomach from the mouth due to the normal nerve function that tells the brain to swallow. For a dog that has megaesophagus, the esophagus widens and the nerve function or normal motility diminishes or disappears. This which makes it difficult for a dog to swallow food and liquids because these items sit in the esophagus and accumulate there instead of in the stomach.
Signs of Megaesophagus in Dogs
Regardless of how megaesophagus occurs, the symptoms will be the same.
Signs of Megaesophagus in Dogs
- Muscle loss
- Difficulty swallowing
- Bad breath
- Rapid breathing
The most obvious sign of megaesophagus is regurgitation. This is different from vomiting because regurgitation is a passive occurrence meaning there is no active effort by the body to expel the contents from the esophagus or stomach. Regurgitated food and liquid seems to fall out of a dog's mouth whereas vomiting includes wretching and gagging. Dogs that try to eat or drink will regurgitate food almost immediately if gravity allows it. This of course causes great difficulty in keeping food or liquids down so swallowing can be impossible. Weight loss and muscle loss are a result of a dog with megaesophagus being unable to get necessary nutrients from food since most food is regurgitated and swallowing is difficult. Bad breath is also common because of the retained food in the esophagus and regular regurgitation.
Rapid breathing can occur if a dog aspirates its food. Aspiration is the result of food or liquid going down the airway instead of the esophagus. When a dog regurgitates, some food or water can go down the trachea instead of the esophagus and make it difficult to breathe and even cause aspiration pneumonia.
Causes of Megaesophagus in Dogs
There are two main types of megaesophagus - congenital and acquired. Dogs that are born with megaesophagus have the congenital form of the disease. It is usually noted by 12 weeks of age in puppies or as they are nursing or being bottle fed. Older dogs develop acquired megaesophagus which may be secondary to another disease or issue or it may have an unknown cause. Things that are known to cause acquired megaesophagus include:
- Myasthenia gravis: This is a disease that affects the nervous system, including the nerves that affect the esophagus.
- Trauma: Any type of injury to the esophagus or nerves that affect the normal function of the esophagus can result in megaesophagus. This includes an obstruction, foreign body, some toxin ingestions, inflammation, excessive vomiting, and other injuries to the esophageal muscle.
- Hypothyroidism: This disease affecting the thyroid gland can affect the esophagus muscle.
- Addison's disease: This disease affecting the adrenal gland of a dog can affect the muscle in the esophagus due to the lack of cortisol in the body.
- Dermatomyositis: Some dogs with this disease can have tissue damage and inflammation from a lack of oxygen in the blood vessels and megaesophagus can result.
Dog Breeds At Risk for Megaesophagus
Any breed of dog can be born with or develop megaesophagus but several breeds have been shown to be much more likely to be inflicted with this problem than others.
Diagnosing Megaesophagus in Dogs
Symptoms will be discussed with your veterinarian but X-rays will be obtained to look at the placement of the trachea and esophagus in your dog. Occasionally a contrast study using barium or endoscopy will also be used.
Treatment for Megaesophagus in Dogs
If a dog develops megaesophagus as a result of Addison's or hypothyroid disease, this problem often resolves once the disease is properly managed. Dogs with other types of acquired megaesophagus and congenital megaesophagus can only manage the symptoms of the disease since there is no cure. Medications to manage the symptoms and special feeding techniques must be used in these cases.
Feeding tubes or elevated feeding techniques are necessary to allow a dog with megaesophagus to eat and drink without regurgitating. Feeding tubes are surgically placed and require regular maintanence and replacement so elevated feeding techniques are more popular for owners with dogs with megaesophagus. Gravity is the enemy when it comes to feeding. Dogs usually eat standing on all four legs so their esophagus is not perpendicular to the ground. This allows the food to slide out of the mouth since it can't fight gravity. But if a dog is eating its food that is placed on a step stool or table, in raised food dishes, or out of a special chair called a Bailey Chair that makes a dog sit up while it eats, gravity is more likely to help the food slide down the esophagus and into the stomach. This along with experimenting between solid and liquified foods is necessary to provide a dog with megaesophagus proper nutrition.
How to Prevent Megaesophagus in Dogs
There is unfortunately no way to prevent megaesophagus in most dogs. With the exception of some forms of trauma, megaesophagus is not something that is preventable, but by knowing the warning signs, you'll be able to better help your dog get the care they need.