With this condition, there is dilation of the esophagus due to a loss of normal peristaltic function. Peristalsis is the process by which waves of muscular contraction move along the contents (food in this case) of tubular organs. Animals with megaesophagus regurgitate undigested food shortly after eating.
This is an autosomal recessive trait in the wire-haired fox terrier, and autosomal dominant in the miniature schnauzer. The mode of inheritance has not been determined for other breeds that are predisposed to this condition.
Although it may not be noticed until young adulthood, this disorder is usually first recognized in puppies around the time of weaning. Affected pups regurgitate food, fail to thrive, and may develop respiratory difficulties associated with aspiration pneumonia due to inhalation of food particles. Signs include laboured breathing, fever and lethargy, and nasal discharge.
Some dogs appear to gradually outgrow this condition (by a year or so), while in others there is no improvement.
Regurgitation of undigested food shortly after eating is the main sign with this disorder. Your veterinarian will take chest x-rays to determine if your dog has megaesophagus, and perform other laboratory tests since there are several conditions that may be associated with this disorder.
If an underlying cause can be identified, treatment may improve esophageal function. There is no specific treatment for the megaesophagus itself, but it can usually be managed by feeding small, frequent, high-caloric meals from an elevated location so that gravity assists the passage of food. Different consistencies of foods can be tried to determine which causes the least regurgitation.
Some dogs appear to outgrow the problem, while in others there is no improvement and feeding management is required for life. Your veterinarian will discuss with you possible complications that you must watch out for, the most serious of which is aspiration pneumonia.
Since megaesophagus may be associated with many different conditions, the diagnostic work-up should include CBC, biochemical profile, urinalysis and survey thoracic radiographs in all cases.
Affected wire-haired fox terriers, their parents (carriers of the trait) and siblings (suspect carriers) should not be bred. Affected miniature schnauzers should not be bred.
In other breeds in which inheritance is unknown, it is safest to avoid breeding affected dogs, their parents and siblings.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Twedt, D.C. 1995. Diseases of the esophagus. In E.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, pp.1124-1142. W.B. Saunders Co., Toronto.
Jenkins, C.C. and Mears, E.A. 1996. What's new in the diagnosis and management of megaesophagus. ACVIM-Proceedings of the 14th Annual Vet. Med. Forum, p. 585-586.
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