Megaesophagus, also known as esophageal dilatation, is a disorder of the

esophagus The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...

in humans and other

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s, whereby the esophagus becomes abnormally enlarged. Megaesophagus may be caused by any disease which causes the muscles of the

to fail to properly propel food and liquid from the mouth into the stomach (that is, a failure of

peristalsis Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...

). Food can become lodged in the flaccid esophagus, where it may decay, be regurgitated, or maybe inhaled into the lungs (leading to

aspiration pneumonia Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complications may incl ...

Humans

Megaesophagus may occur secondary to diseases such as

achalasia Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esopha ...

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the ...

. Achalasia is caused by a loss of ganglion cells in the myenteric plexus. There is a marked lack of contraction within the muscles involved in peristalsis with a constant contraction of the lower esophageal sphincter. Dilation of the esophagus results in difficulty swallowing. Retention of food bolus is also noted.

Other animals

Dogs

Megaesophagus can also be a symptom of the disease

myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, ...

. Myasthenia gravis is a neuromuscular disease where the primary symptom is weakness in various body parts of the dog. However, when myasthenia gravis occurs in older dogs it is thought of as an immune-mediated disease. Often when myasthenia gravis is diagnosed in older dogs the first symptom the dog may manifest is megaesophagus. Myasthenia gravis occurs when

acetylcholine receptor An acetylcholine receptor (abbreviated AChR) or a cholinergic receptor is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter. Classification Like other transmembrane receptors, acetylcholine receptor ...

s (nicotinic acetylcholine receptors) fail to function properly, so that the muscle is not stimulated to contract. There is an invention known as the "bailey chair" that uses the force of gravity to push down liquids and food into the dog's stomach. Usually dogs are known to understand when it is time to eat in their bailey chair, and this helps prevent issues. Bailey chairs can be made and are sold. Also, a simple chair turned upside down can be successfully used for this purpose. Apparatus for dog megaesophagus

In two unrelated incidents in

Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

megaesophagus developed in dogs that had eaten certain brands of dog food; however, no agent that could have caused the disorder has been found in lab tests of the food.

Diagnosis

An important distinction in recognizing megaesophagus is the difference between when a dog regurgitates or vomits. When a dog regurgitates there is usually not as much effort involved as when a dog vomits. Often when regurgitating, the dog will tip its head down and the liquid and/or food will almost appear to "spill out" of its throat. One of the primary dangers to a dog with megaesophagus is

. Because the food stays lodged in the throat, it can often be inhaled into the lungs causing aspiration pneumonia. One way to avoid this is to make sure that every time the dog eats or drinks anything, that the dog sits for at least 10 minutes afterward or is held in a sitting up or begging position. This disorder has a guarded prognosis, however, a successful management technique is vertical feeding in a Bailey chair.

Affected breeds

* Basset Fauve de Bretagne * Bernese Mountain Dog * Bichon Frise * Boston Terrier * Chihuahua * Cocker Spaniel *

Dachshund The dachshund ( or ; German: 'badger dog'), also known as the wiener dog or sausage dog, badger dog, doxen and doxie, is a short-legged, long-bodied, hound-type dog breed. The dog may be smooth-haired, wire-haired, or long-haired, with varie ...

English Springer Spaniel The English Springer Spaniel is a breed of gun dog in the Spaniel group traditionally used for flushing and retrieving game. They are descended from the Norfolk or Shropshire Spaniels of the mid-19th century; the breed has diverged into sepa ...

* French Bulldog *

German Shepherd The German Shepherd, also known in Britain as an Alsatian, is a German Dog breed, breed of working dog of medium to large size. The breed was developed by Max von Stephanitz using various Old German herding dogs, traditional German herding dog ...

* German Spitz * Golden Retriever *

Great Dane The Great Dane is a German list of dog breeds, breed of large mastiff-sighthound, which descends from hunting dogs of the Middle Ages used to hunt bears, wild boar, and deer. They were also used as guardian dogs of German nobility. It is one o ...

Greyhound The English Greyhound, or simply the Greyhound, is a dog breed, breed of dog, a sighthound which has been bred for coursing, greyhound racing and hunting. Some are kept as show dogs or pets. Greyhounds are defined as a tall, muscular, smooth-c ...

* Irish Setter * Irish Wolfhound * Italian Greyhound *

Labrador Retriever The Labrador Retriever or simply Labrador or Lab is a British list of dog breeds, breed of water dog retriever gun dog. It was developed in the United Kingdom from St. John's water dogs imported from the Newfoundland Colony, colony of Newfoun ...

Miniature Schnauzer The Miniature Schnauzer is a dog breed, breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers may have been developed from the smallest specimens of the Standard Schnauzer, or c ...

Newfoundland dog The Newfoundland is a large breed of working dog. They can be black, grey, brown, or black and white. However, in the Dominion of Newfoundland, before it became part of Canada, only black and Landseer (white-and-black) coloured dogs were cons ...

* Rottweiler *

Shar Pei The Shar Pei () is a dog breed from southern China. Traditionally kept as a property guardian, the shar pei was driven to the brink of extinction in the 20th century. The breed is known in the West for its deep wrinkles, while a traditional less ...

* Shih Tzu * Welsh Corgi * Welsh Terrier * Wire Fox Terrier * Yorkshire Terrier

Cats

Affected breeds: * American Shorthair *

Persian (cat) The Persian cat, also known as the Persian Longhair, is a long-haired breed of cat characterised by a round face and short muzzle. The first documented ancestors of Persian cats might have been imported into Italy from Khorasan as early as a ...

Siamese (cat) The Siamese cat (; แมวสยาม, Maeo Sayam; แมววิเชียรมาศ, Maeo Wichien Maat) is one of the first distinctly recognised List of cat breeds, breeds of Asian cat. It derives from the Wichianmat landrace. The ...

Horses

Megaesophagus is rare in horses. It is more frequently reported in Friesian horses than in other breeds.

Congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

megaesophagus is usually identified when a foal begins to eat solid food from the ground; prior to this, as the foal nurses milk from its mother, the milk passes easily down into the stomach. The most common signs are difficulty swallowing (

dysphagia Dysphagia is difficulty in swallowing. Although classified under " symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or l ...

) and inhalational pneumonia.

References

External links

Canine megaesophagus
{{Digestive system diseases Dog diseases Esophagus disorders