What is esophageal diverticula:
It is important to remember that “megaesophagus” really is a “catch-all” – “umbrella” type of classification for esophageal disorder(s)/disease for many.

Esophageal Diverticula, definition as per Merck (human med):
http://www.merck.com/mmpe/sec02/ch012/ch012f.html
An esophageal diverticulum is an outpouching of mucosa through the muscular layer of the esophagus. It can be asymptomatic or cause dysphagia and regurgitation. Diagnosis is made by barium swallow; surgical repair is rarely required.

Esophageal Diverticula, definition as per Merck (veterinary med):
http://www.vetmanual.org/mvm/index.jsp?cfile=htm/bc/23208.htm
Diverticula are pouch-like dilatations of the esophageal wall and may be congenital or acquired. They are rare in dogs and cats. Acquired diverticula are of 2 types: pulsion or traction. Pulsion diverticula are caused by increased intraluminal pressure or deep esophageal inflammation, which can lead to mucosal herniation. Predisposing diseases include esophagitis, esophageal stricture, foreign bodies, vascular ring anomalies, megaesophagus, and hiatal hernia. This type of diverticulum consists of esophageal epithelium and connective tissue. Traction diverticula result from inflammation in the chest cavity in close proximity to the esophagus. Fibrous tissue is produced, which then contracts, pulling the esophageal wall outwards. This diverticulum consists of all 4 layers of the esophagus.

Small diverticula may be subclinical. Large diverticula allow food to become trapped in the pouch leading to postprandial dyspnea, regurgitation, and anorexia. Survey radiographs may show the diverticulum if it is full of ingesta or air, but contrast radiographs are best to demonstrate the pouch. Endoscopy will also allow visualization and can identify ulceration and scarring.

Small diverticula may be treated with a bland, soft diet fed with the animal in an upright position. Large diverticula require surgical excision and reconstruction of the esophageal wall. The prognosis after surgery is fair to good.

Example of a case I am next offering as an “aside” scenario, xxxxx with xxxxx came to this group after his boy was diagnosed as having megaesophagus. He (like many are) was a bit frustrated that they weren’t making enough progress (symptom reduction), and intuitively kept digging for more/better/different answers for his boy. He went to the GSD Genetics Forum, telling xxxxx’s story (diagnosis, symptoms, response or lack thereof to current therapy/daily protocols). A couple of members there put 2+2 together a bit differently and sent xxxxx some info. xxxxx took that info back to his DVM Specialists. It would be good for xxxxx to be sharing this in more detail (and eventually he will), but one thing was added to xxxxx’s treatment plan based on the info given (it was a can’t hurt to try type of thing & validity in the info was found interesting by the DVM/Specialists). Results? Astonishing (knock on wood – thus far, still astonishing @ the last update I had from xxxxx). xxxxx is no longer symptomatic. Diagnosis was changed to esophageal spasms, a topic which I have tried to share about here before. Here is a search query via Merck Veterinary for those who wish to learn more — but please note (!) Merck Veterinary http://www.merckvetmanual.com/mvm/index.jsp does not offer info on either esophageal spasms or diffuse esophageal spasms, so back to human med. we go:

http://www.merck.com/mmpe/search.html?qt=esophageal+spasms&qp=%2Bsite%3Awww%2Emerck%2Ecom+%2Burl%3A%2Fmmpe+%2Durl%3Aprint%2F+%2Durl%3Aindex%2F+%2Durl%3Aresources%2Fpronunciations+%2Durl%3Amultimedia%2F+%2Durl%3A%2Fmmpe%2Fau+%2Durl%3A%2Fmmpe%2Fag+%2Durl%3Alexicomp%2F&charset=utf8&la=en&start=0