Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

258 •DOG OWNER’S HOME VETERINARY HANDBOOK
DYSPHAGIA (DIFFICULT, PAINFUL SWALLOWING)
A dog with a painful esophagus eats slowly, stretches his neck, and makes
repeated efforts to swallow the same mouthful. As the condition becomes
more painful, the dog stops eating and begins to lose weight.
Difficult, painful swallowing indicates a partial blockage caused by an
esophageal foreign body, stricture, or tumor. Pain on swallowing also occurs
with mouth infections, sore throat, and tonsillitis.
MEGAESOPHAGUS (ENLARGED ESOPHAGUS)
Megaesophagus means enlarged esophagus. When the esophagus is partially
obstructed over a period of time, it gradually enlarges like a balloon and
becomes a storage organ. This process, called megaesophagus, is accompanied
by regurgitation, loss of weight, and recurrent episodes of aspiration pneumonia.
There are two causes of megaesophagus. The first is a failure of the esophagus
to contract and propel food into the stomach. This impaired motility
occurs as a hereditary disorder in puppies and as an acquired disease in adults.
The second cause of megaesophagus is a physical blockage, such as a foreign
body or a developmental problem with abnormal blood vessels that encircle
the esophagus.
Congenital megaesophagus is a hereditary form of the disease that occurs
in puppies. It is caused by a developmental disorder involving the nerve
plexus in the lower esophagus. Peristaltic activity stops at the level where the
esophagus is paralyzed, and food can go no further. In time, the esophagus
above the inert segment enlarges and balloons out. This can be seen by lifting
the puppy by his back legs and looking for a bulging out of the esophagus at
the side of the neck.
Congenital megaesophagus has been described in German Shepherd Dogs,
Golden Retrievers, Great Danes, Irish Setters, Greyhounds, Labrador
Retrievers, Newfoundlands, Miniature Schnauzers, Chinese Shar-Pei, and
Wire Fox Terriers. Hereditary myopathies (see page 363) are other causes of
congenital megaesophagus.
Puppies with congenital megaesophagus show signs at weaning, when they
begin to eat solid foods. Characteristically, they approach the food dish with
enthusiasm but back away after a few bites. They often regurgitate small
amounts of food, which they eat again. After repeatedly eating the food, it
becomes quite liquid and passes into the stomach. Repeated inhalation of
food causes bouts of aspiration pneumonia.
Another type of congenital megaesophagus is caused by retained fetal
arteries in the chest. The arteries produce a constriction around the esophagus
(known as vascular ring anomaly) that prevents swallowing. The most
common anomaly is a persistent right aortic arch. Regurgitation and difficulty