Issue Description Megaesophagus is the most common cause for
regurgitation in the dog. Regurgitation results from the inability of
the esophagus to contract properly and propagate the food down to the
Causes Most cases involve young puppies (Great Danes,
Irish Setters, German Shepherds are genetically predisposed). In these
cases the condition is believed congenital though it often does not
show up until the pup begins to try solid food. Congenital
megaesophagus is believed to occur due to incomplete nerve development
in the esophagus. The good news is that nerve development may improve
as the pet matures. Prognosis is thus better for congenital
megaesophagus than it is for megaesophagus acquired during adulthood.
Another congenital problem is the "Vascular Ring Anomaly." This is a
band of tissue constricting the esophagus. Such tissue bands are
remnants of fetal blood vessels which are supposed to disappear before
birth. They do not always do so. Improvement is obtained when the band
is surgically cut but in 60% of cases some residual regurgitation
In adult dogs, diseases that cause nerve damage
can lead to Megaesophagus. Myasthenia gravis would be a common cause
and very important to rule in or out. Myasthenia gravis is a condition
whereby the nerve/muscle junction is destroyed. Signals from the
nervous system sent to coordinate esophageal muscle contractions
simply cannot be received by the muscle. Megaesophagus is one of its
classical signs though general skeletal muscle weakness is frequently
associated. This condition is treatable but special testing is needed
to confirm it. Scarring in the esophagus (as would occur after a
foreign body episode or with damage to the esophagus from protracted
vomiting) may be sufficient to interrupt neurologic transmissions or
even narrow the esophagus so that food cannot pass through it.
Technically, this is not a true megaesophagus as the muscles are
working normally; there is simply an obstruction present. Special
balloons can be inserted in the esophagus to dilate the narrowed area
but some residual regurgitation is likely to persist. Tumors of the
esophagus may have similar effects in that they, too, can cause
Hypothyroidism may be associated with
megaesophagus. It is easy to rule thyroid disease in or out with blood
testing and it is important to treat a thyroid hormone deficiency;
however, megaesophagus usually does not correct with thyroid
replacement therapy. Whether or not hypothyroidism can truly cause
megaesophagus is still being debated.
Addison's disease (hypoadrenocorticism) has also been associated with
megaesophagus though this would be a rare cause. This condition
represents a deficiency of cortisone production by the adrenal gland.
This deficiency alters the metabolism of esophageal muscle. Diagnosis
and treatment are not difficult.
External obstruction of the esophagus could cause a similar syndrome
by creating a blockage. A mass in the chest could pinch the esophagus
Many of the above conditions are treatable and it is important to find
a cause for megaesophagus if it is at all possible to do so.
Unfortunately, most cases do not have a clear cause and must be
managed as they are.
Diagnosis First, the megaesophagus must be diagnosed.
This is done radiographically. If megaesophagus is not obvious on
plain films, it is better not to use contrast (Barium) studies if
possible. This is because megaesophagus patients have the tendency to
inhale or "aspirate" food contents that back up in their throats. This
is dangerous enough when the material is simply food but if barium is
present and becomes inhaled, the body has great difficulty removing it
from the lungs. Still, sometimes this is the only way to see the
The next step is to determine whether or not
the animal has "aspiration pneumonia" from inhaling regurgitated food
material. Chest radiographs in combination with a history of cough,
nasal discharge, and the presence of fever indicate pneumonia. Usually
the chest radiographs will show disease in the areas of the chest
which are lowest in the standing animal as this is where gravity draws
inhaled material. The presence of aspiration pneumonia makes the case
much more serious as pneumonia can be a life-threatening condition.
Endoscopy is an important diagnostic test for the megaesophagus
patient and, if possible, should be done in all cases. In endoscopy a
long skinny tube with a special camera on the end is passed down the
esophagus to the stomach. Ulcers on the esophageal walls will be seen
and any narrowings will be obvious. Biopsies can be taken if any
suspicious lesions are present.
Blood testing to rule in or
out treatable causes of megaesophagus should be performed.
Treatment The first step is to determine if the dog does
better with a liquid or solid diet. Every individual is different. One
must train the dog to eat in an elevated position. Ideally, the pet
should be kept in this position for 10-15 minutes after the meal.
Feeding tubes can be placed directly in the stomach for more
convenient feeding. If the "cardiac sphincter" which separates the
stomach from the esophagus is weak, though, regurgitation may still
occur. A medication called Metoclopramide (trade name: Reglan) may
help increase the tone of this sphincter.
nausea may be helpful for patient comfort and strong antacids will
help minimize acid related damage to the esophagus when food is
regurgitated from the stomach.
There is a motility modifier
called "Cisapride" which is helpful to many cases. Theoretically this
should not be so as the type of muscle in the dog's esophagus is not
of a type that should be affected by this medication. Nonetheless,
many individuals experience fewer episodes of regurgitation while on
cisapride. Given the difficulty in managing this condition, we
recommend at least a one week trial for any megaesophagus patient.
Cisapride also is able to increase cardiac sphincter tone. Cisapride
is no longer commercially available in the U.S., but it can be made up
by most "compounding pharmacies."
Aspiration pneumonia is
treated with fluids and antibiotics as is any other bacterial
pneumonia, though these individuals may re-aspirate at any time and
require treatment all over again. Hospitalization may be required.