Megaesophagus is a condition characterized by an enlarged and
malfunctioning esophagus, which is the tube that carries food
and liquids from the mouth to the stomach. When the esophagus
is functioning properly, a reflex causes contractions that
propel food and water into the stomach. Another reflex prevents
breathing during swallowing so that a cat will not inhale food
or liquids into the lungs.
In cases of megaesophagus, a disease, physical blockage, or
congenital defect will cause these reflexes to fail, and the
esophagus will lose muscle tone and remain enlarged rather than
contracting. Because foods and liquids cannot make their way
into the stomach, a cat may regurgitate and begin to lose weight. In addition, foods or
liquids that are inhaled into the lungs can cause aspiration
pneumonia, which can be fatal if not treated promptly.
Here we will review the causes, symptoms, and treatments of
megaesophagus in cats so that you will know what to look out
for and when to seek help.
Causes of Megaesophagus in Cats
Megaesophagus in cats is either congenital (present since
birth) or acquired.
In congenital cases, the cause may be unknown, or it may be the
result of a genetic developmental abnormality that causes
inadequate nerve function.
Siamese cats seem to be at particular risk for congenital
megaesophagus.
In acquired cases, the condition is either primary or
secondary. In primary cases, the cause is commonly idiopathic,
or not traceable. In secondary cases, megaesophagus is the
result of another medical issue, such as a foreign object
blockage, esophageal tumor, heavy metal poisoning, parasitic
infection, or a neuromuscular disease. Neuromuscular diseases
are those in which muscle function is impaired because muscles
are not receiving signals from the nervous system. In the case
of megaesophagus, the impairment would be seen in the
esophageal muscle that is failing to contract.
Symptoms of Megaesophagus in Cats
The most common symptoms of megaesophagus in cats include:
- Regurgitation (this is different than vomiting; vomiting is when contents are
actively pushed out of the stomach; regurgitation is when
contents fall out of the mouth or throat)
-
Weight loss
- Symptoms associated with aspiration pneumonia: coughing,
nasal discharge, difficulty breathing, difficulty swallowing,
lethargy, weakness, fever,
blue-tinted skin.
Treatment for Megaesophagus in Cats
To diagnose megaesophagus, your veterinarian will perform a
physical examination on your
cat, ask you about their symptoms, and use certain tests.
X-rays and ultrasounds are commonly used because they can
reveal an enlarged esophagus, material in the esophagus, and
abnormalities associated with aspiration pneumonia.
There is no cure for megaesophagus. In some cases, surgery may
be attempted to correct a congenital defect, but it can be
risky.
In most cases -- whether congenital or acquired -- treatment
will be purely supportive, and the goal of treatment is to
improve swallowing and digestion.
If your cat is suffering from aspiration pneumonia, they may
require immediate hospitalization and antibiotics. Once the aspiration
pneumonia is resolved, supportive treatments may include:
- Many cats with megaesophagus are switched to a liquid diet
because it is easier to swallow. The food is typically placed
at an elevated position so that the cat is standing on their
hind legs while eating. This allows gravity to work in pushing
the food into the stomach. A cat who is unable to eat may
require a feeding tube.
- Medications such as Metoclopramide may be prescribed to
improve gastrointestinal movement. Antacids and anti-nausea
medications may also be used to prevent damage to the esophagus
and improve the catโs overall comfort level.
The prognosis for cats with megaesophagus can vary. Cats with
congenital forms tend to fare worse, and many cats will succumb
to aspiration pneumonia. Other cats, however, will do well with
modifications to their diet and feeding routine.
Why Megaesophagus In Dogs Is Difficult To Treat
The esophagus -- the tube that connects the mouth to the
stomach -- plays an important role in digestion. When
functioning normally, a reflex causes contractions in the
esophagus that move ingested food into the stomach. Other
reflexes prevent breathing during swallowing so that food and
liquids cannot be inhaled into the lungs.
In some dogs, a congenital defect, disease, or physical
blockage can cause these reflexes to fail, resulting in an
esophagus that loses all muscle tone and instead of
contracting, remains enlarged. This is what is referred to as
megaesophagus.
When megaesophagus occurs, ingested food remains in the
esophagus, often leading to regurgitation and weight loss. Food that is lingering in
the esophagus can also make its way into the lungs, resulting
in sometimes fatal episodes of aspiration pneumonia.
Read on to learn all about megaesophagus in dogs.
Causes of Megaesophagus in Dogs
Megaesophagus can either be a congenital defect (one present
since birth) or acquired later in life.
In congenital cases, the defect is either idiopathic (meaning
the cause is not known) or it is the result of an inherited
developmental abnormality, such as a persistent right aortic
arch. Aortic arches are blood vessels that serve a function in
fetuses, but disappear when the animal is born because they are
no longer needed. In some animals however, these blood vessels
fail to disappear, and because the right aortic arch is near
the esophagus, it creates a situation in which the esophagus is
essentially squeezed between the heart and the blood vessel.
This causes compression of the esophagus as well as dilation of
the esophagus in front of the compressed section.
While congenital megaesophagus can occur in any dog, there
seems to be a hereditary predisposition in certain breeds,
including the Labrador
Retriever, Golden
Retriever, Great
Dane, German
Shepherd, Irish
Setter, Newfoundland, Miniature
Schnauzer, and Chinese
Shar-Pei.
In acquired cases, megaesophagus is either primary or
secondary. In primary cases, the cause is idiopathic. In
secondary cases, the condition is a result of another issue,
such as a blockage in the esophagus or a disease. Diseases that
can result in megaesophagus include hypothyroidism, esophagitis,
hypoadrenocorticism, heavy metal poisoning, autoimmune
diseases, and myasthenia gravis. Myasthenia gravis is a
neuromuscular disease and the most common cause of secondary
megaesophagus in dogs; it interrupts communication between the
nervous system and esophageal muscle so the esophageal muscle
does not receive signals that tell it to contract.
Symptoms of Megaesophagus in Dogs
The most common symptoms of megaesophagus in dogs include:
Regurgitation is different than vomiting. Vomiting is when the
body actively pushes contents out of the stomach. Regurgitation
is when food or liquid falls out of the mouth or throat.
A dog with megaesophagus will often lose weight because food is
not making its way to the stomach.
Aspiration pneumonia can occur when food
sitting in the esophagus is inhaled into the lungs. The
symptoms of aspiration pneumonia include difficulty breathing,
difficulty swallowing, coughing, nasal discharge, fever,
increased heart rate, weakness, lethargy, and a bluish tint to
the skin.
Treatment for Megaesophagus in Dogs
Megaesophagus is typically diagnosed with a chest x-ray or
ultrasound that shows an enlarged esophagus, aspiration
pneumonia, or material in the esophagus.
Megaesophagus can be difficult to treat. Some puppies with
congenital megaesophagus may outgrow the condition, and surgery
may be possible for certain development abnormalities. Dogs
with congenital forms of the condition should not be bred as it
may be passed to their offspring.
Acquired cases of megaesophagus cannot be reversed. For these
dogs, treatment is essentially supportive, and may include:
- Treating respiratory infections with antibiotics as soon as
they occur.
- Managing your dogโs eating.
Ask your
veterinarian to recommend a food that will be good for
your dog, and adjust your dogโs feeding schedule so that they
have small meals frequently instead of large meals once or
twice a day.
Elevating your dogโs food bowl so that their head is up while
eating can help to move food into the stomach by way of
gravity. Many pet parents use a step ladder or Bailey chair to
elevate their dogโs bowl.
If the dog is unable to eat on their own, a veterinarian may
recommend a feeding tube.
- Medications may be useful in some cases. Metoclopramide can help to
increase muscle tone around the esophagus and stimulate
contractions. Antacids can help to reduce esophageal damage,
and nausea medications can reduce stomach upset.
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