Megaoesophagus

The oesophagus is the muscular tube that takes food from the mouth to the stomach.  This is done by waves of muscular contractions, called peristalsis, which push the food along the tube.

Megaoesophagus (MO) refers to a large, flabby oesophagus which makes it difficult or impossible for food to reach the stomach because the peristaltic action does not happen as it should, probably because the nerves are not functioning properly.  Food cannot enter the stomach normally, but instead simply sits in the enlarged oesophagus and is eventually regurgitated.

Some cases of MO in Irish Setters are congenital, i.e. present at birth, but it may not be noticed that the pup has any problem until it is weaned when he will regurgitate food through the mouth and maybe fluids through the nose.  It may cough and make gurgling, rattling sounds. An affected pup generally will not thrive and will probably be smaller than his littermates.

MO can also be acquired later in life (about 4 years of age onwards) with similar clinical signs and poor prognosis.

The signs of MO are as follows:

Regurgitation may be considered the most typical sign of MO.  Weight loss with possible muscle wasting and a failure to thrive with a general weakness are common.  Increased swallowing motions with excessive drooling and dehydration are possible.  A ravenous appetite but with stunted growth or weight loss are usual, as is coughing, difficulty in breathing and pneumonia.

Regurgitation is different from vomiting:  Vomiting occurs when the contents of the stomach are expelled by muscular contractions of the abdomen.  Regurgitation is purely the return of food that has not reached the stomach and, as such, retching does not happen.  As it happens very quickly and with little effort littermates or mum may clean up the results before the breeder realizes it has happened.

Dogs with MO may not exhibit all of these signs, or even any of them to a significant degree.  Sometimes the only signs may be repeated bouts of aspiration pneumonia, or a wet cough that fails to clear up.  Some pups with congenital MO can grow out of the disorder and go on to enjoy a normal quality of life but others will be significantly affected and need careful food management for the rest of their lives.  If the problem is severe, however, the pup will not be able to get enough food and will have to be euthanased. Acquired disease in adult dogs never resolves.

A definitive diagnosis can be obtained by giving a barium meal.  In a normal pup, the barium will move into and through the stomach, but in the dog with MO, most of it will be seen collected in the oesophageal pouch in front of the stomach.

Another congenital reason for regurgitation is a vascular ring anomaly such as persistent right aortic arch.  Foetal blood vessels that should have disappeared at birth create a fibrous band that constricts the oesophagus.  This causes the oesophagus above the constriction to expand as the food cannot pass through the constricted area.  If caught in time, the vascular ring can be cut and the oesophagus often returns to normal.  Delaying surgery may cause irreparable oesophageal damage.

Oesophageal dilation and vascular ring anomalies are both believed to have a hereditary component because there is a breed disposition and a probable family predisposition.

If you believe your pet has MO then you will need veterinary advice.  If confirmed it is important to let your breeder know as well as the secretary of one of the breed clubs as information is being collected on the problem.

Megaoesophagus is one of the twenty inheritable gastro-intestinal diseases listed in the Merck Veterinary Manual and is listed as a severe trait in the “Hierarchy of Disagreeableness of a Genetic Trait”.

 www.merckvetmanual.org/mvm/htm/bc/100419.htm

 Follow the next link to an excellent article on MO with clear X rays of a dog without MO and one with MO. There is also a very clear visual of a dog with MO trying to eat

 http://www.marvistavet.com/html/body megaesphagus.html/

Sometimes MO doesn’t happen until later in life, maybe through trauma or being associated with other health problems but this form is not generally a problem with Irish Setters.

Can you help?

If you breed a litter with MO or your puppy is diagnosed with MO please let the Breed Health Committee know so we can monitor the prevalence in the breed.

 

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