Australian Shepherd Health & Genetics Institute

Australian Shepherd Health & Genetics Institute

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What is megaesophagus?

Megaesophagus is an abnormally enlarged esophagus which prevents the dog from swallowing normally and passing food into the stomach.  It can also be secondary to persistent right aortic arch (PRAA), a congenital blood vessel abnormality, or myasthenia gravis, an autoimmune disease.  In dogs with PRAA, the abnormal vessels encircle and constrict the puppy’s esophagus.  The stricture causes food to back up and stretching of the esophageal issue.  Whatever the primary cause, affected dogs tend to regurgitate their food and are at risk of developing aspiration pneumonia.  The condition has a very poor long-term prognosis.

What is the most likely cause of megaesophagus in an Aussie?

All cases reported to ASHGI have been in puppies with persistent right aortic arch but there have also been cases of myasthenia gravis so it is possible that a dog could have it due to that disease..

Is megaesophagus inherited?

The primary form of this disease is inherited, but it is not kown to occur in Aussies.  However, even secondary megaesophagus also has genetic roots because the diseases that can cause it are also hereditary.

How can I control megaesophagus in my breeding program?

No dog with megaesophagus should be bred.    Don’t repeat the cross that produced it or breed the parents and healthy siblings close on their own pedigree or to anything with a family history of megaesophagus, PRAA or myasthenia gravis.  If any breeding dog produces it with more than one mate serious consideration should be given to removing that dog from further breeding.