Megaesophagus in dogs is a condition that leads to the inability of food and liquid to pass into the stomach. It occurs when there is an abnormal enlargement of the esophagus, which interrupts the normal flow of food and liquid. Symptoms involve difficulty swallowing, hypersalivation, coughing, regurgitation, and weight loss. Treatment includes dietary changes and medications to help control symptoms. Primary (idiopathic) and secondary (acquired) megaesophagus are two types of esophageal motility disorders. Primary megaesophagus occurs in both congenital and adult-onset forms, whereas secondary megaesophagus is only seen in adults. While it is typically seen in older dogs (and occasionally cats), it can occur in any dog at any age. This article will explore everything you need to know about megaesophagus in dogs.
What are the causes of megaesophagus in dogs?
Primary causes
Primary megaesophagus occurs as both congenital and adult-onset forms and affects the esophagus directly. The development of megaesophagus results from either a defect in the nerves that supply the esophagus or an abnormality in the development of the esophageal neuromuscular system.
Secondary causes
Megaesophagus may develop secondary to a number of disorders. Obstructive conditions, muscular and neurological disorders, and certain toxins can cause megaesophagus in dogs. Some of the more common causes include:
- Esophagitis
- Botulism and tetanus
- Lead poisoning
- Addison's disease
- Hypothyroidism
- Cancer of the esophagus
- Myasthenia gravis
What are the symptoms of megaesophagus in dogs?
The primary symptom of megaesophagus is regurgitation. Regurgitation is the effortless spitting up of food or water that occurs soon after eating or drinking. Vomiting, on the other hand, is the forceful expulsion of its contents from the stomach through the mouth. Your veterinarian needs to distinguish between regurgitation and vomiting. Common clinical symptoms of megaesophagus in dogs are:
- regurgitation
- hypersalivation
- dysphagia
- weakness
- weight loss
- failure to gain weight
- poor body condition
How is megaesophagus diagnosed in dogs?
A presumptive diagnosis of megaesophagus can be made based on clinical signs. The definitive diagnosis then requires an X-ray to show the enlarged esophagus and barium contrast studies that demonstrate problems with movement through the esophagus.
How is megaesophagus treated in dogs?
If possible, the causes of the secondary megaesophagus must be identified and resolved. Treatment of megaesophagus and other symptoms is possible with successful treatment of the underlying conditions, such as esophagitis, myasthenia gravis, hypothyroidism, certain toxicities, etc.
One study showed that sildenafil reduced the number of regurgitation episodes; was associated with increased weight gain, and helped to improve clinical signs and radiographic abnormalities in dogs with congenital megaesophagus.
In primary megaesophagus, treatment consists of supportive therapy. Patients with secondary megaesophagus also require supportive therapy to aid the movement and passage of food or liquid through the esophagus because gravity plays a large factor in aiding this process.
In order to get around this, patients with secondary megaesophagus should have their bowls elevated at head height because that allows them more room (i.e., space) so they can easily maneuver themselves into position on their own accord when eating or drinking is necessary.
Bailey Chairs are available commercially which help keep pets upright while they eat by providing cushioning support while seated in a chair designed specifically for dogs who cause back issues due to overfeeding-even if these cannot be addressed as part of medical treatment options. The form of food fed may vary based on an animal's ability/capacity, but gruel and soft foods offer ample calories without additional hassle from chewing.
What is the best food to feed dogs with megaesophagus?
Most owners and veterinarians are concerned with how underweight these dogs can be and want to add calories for quick weight gain. Most dogs with megaesophagus cannot tolerate kibble diets and therefore pet owners need to feed a gruel or canned food to prevent regurgitation. The concern with these diets is the lack of calories they provide.
Some tips on how to increase the caloric amount of these diets are to supplement with coconut milk or even honey. Coconut milk contains 34 kcal/tsp and honey contains 21 kcal/tsp. It is very important however that no more than 10% of the daily calories come from these supplements.
What is the life expectancy of dogs with megaesophagus?
The improvement rate for dogs with congenital megaesophagus ranges from 20 to 46%. Congenital megaesophagus is when the puppy is born with it.
With successful management of the underlying disorder, clinical signs and esophageal abnormalities can resolve in some dogs with secondary megaesophagus.
There have been some studies that have revealed a less-than-optimistic prognosis for certain types/causes of megaesophagus. The overall median survival time in one study of 71 dogs with generalized, secondary megaesophagus was 90 days. The presence of aspiration pneumonia on radiographs and the age at which clinical symptoms first appeared were found to reduce survival time.
With that being said, patients with megaesophagus at our practice, Kingsdale Animal Hospital, tend to do well because they are managed properly and have very dedicated owners. We have patients that have had megaesophagus for years and the owners are managing them amazingly well and know what to look for when problems arise.
What are the potential complications with megaesophagus?
Aspiration pneumonia is a frequent complication of megaesophagus. In one research study of 89 dogs with megaesophagus, 38% had aspiration pneumonia at the time of diagnosis.
Typical symptoms of aspiration pneumonia include coughing, difficulty breathing, nasal discharge, and lack of appetite. Aspiration pneumonia has the potential to become a fatal complication and therefore if you notice any of the above symptoms, contact your veterinarian immediately.
How does megaesophagus progress to aspiration pneumonia?
Dogs with megaesophagus often have an abnormal swallowing reflex which can result in food material and water entering the lungs and causing pneumonia. In addition, food can accumulate in the esophagus which can lead to aspiration when the dog is lying on its side.
Megaesophagus is a condition that affects a dog’s esophagus, the muscular tube that carries food from the mouth to the stomach. Megaesophagus can make it difficult for a dog to swallow and can be life-threatening if not treated. We hope you find this article helpful in learning more about megaesophagus in dogs and how to manage it. If you have any questions or concerns about your dog’s condition, please contact your veterinarian for individualized care! Thanks for reading.