Megaesophagus in Horses: Causes, Symptoms, Diagnosis, and Management

Megaesophagus is a rare but serious condition in horses where the oesophagus (the muscular tube connecting the mouth to the stomach) becomes abnormally enlarged and loses its ability to move food effectively. This condition can lead to chronic choke, weight loss, malnutrition, and aspiration pneumonia if not properly managed.

Although more common in dogs, megaesophagus in horses is increasingly recognised thanks to advances in diagnostic imaging and veterinary awareness. Understanding its causes, signs, and management strategies is crucial for horse owners, particularly those whose animals suffer from repeated episodes of choke or unexplained weight loss.

What Is Megaesophagus?

Under normal circumstances, the oesophagus uses rhythmic muscular contractions (called peristalsis) to push food and water from the mouth to the stomach. In horses with megaesophagus, these contractions are weakened or lost altogether. The oesophagus stretches and dilates, causing food and saliva to accumulate instead of moving smoothly into the stomach.

As a result, affected horses often regurgitate feed and saliva, struggle to swallow properly, and are at risk of developing choke and aspiration pneumonia (when food or fluid enters the lungs).

Causes of Megaesophagus in Horses

Megaesophagus can be either congenital (present at birth) or acquired later in life due to another underlying problem.

1. Congenital Megaesophagus

This form is very rare in foals and is thought to result from abnormal development of the oesophageal muscles or nerves. Affected foals may show difficulty swallowing from birth, often regurgitating milk through the nose or failing to thrive.

2. Acquired Megaesophagus

In adult horses, megaesophagus usually develops secondary to another issue that damages or interferes with oesophageal function. Common causes include:

• Chronic or severe choke – Prolonged blockage can stretch or injure the oesophagus.
• Oesophageal strictures or scarring – Following injury, ulceration, or surgery.
• Neuromuscular disorders – Conditions affecting the nerves or muscles controlling peristalsis.
• Trauma – Damage to the neck or chest can disrupt nerve signals to the oesophagus.
• Inflammatory or infectious disease – Certain systemic infections or inflammatory conditions may impair oesophageal motility.
• Toxins or metabolic diseases – Though rare, some toxins can affect muscle function.

In some cases, no obvious cause is found, and the condition is considered idiopathic.

Signs and Symptoms

The clinical signs of megaesophagus vary depending on severity but often overlap with symptoms of choke or other swallowing disorders. Common signs include:

• Repeated episodes of choke, often after eating dry or coarse feed
• Nasal discharge containing saliva or feed material
• Difficulty swallowing (dysphagia)
• Coughing, especially after eating or drinking
• Weight loss despite a good appetite
• Poor body condition or muscle wasting
• Signs of aspiration pneumonia (fever, nasal discharge, coughing, laboured breathing)
• Regurgitation of food or fluid soon after swallowing

Foals may show poor growth, frequent milk regurgitation, or respiratory infections early in life.

Diagnosis

Diagnosing megaesophagus requires veterinary examination and specialised imaging. Because symptoms resemble choke or dental problems, thorough diagnostics are essential.

1. Clinical Examination

Your vet will begin by reviewing the horse’s history, including any past choke episodes, changes in eating habits, or weight loss. They’ll also inspect the mouth and throat to rule out dental or structural problems.

2. Endoscopy

Endoscopy involves inserting a flexible camera through the nostril into the oesophagus. This allows the vet to directly view the lining of the oesophagus and identify dilation, inflammation, scarring, or food accumulation.

3. Radiography (X-rays)

Contrast radiographs using barium or other safe contrast fluids can outline the oesophagus and reveal areas of dilation or poor motility. This is especially useful for confirming the diagnosis.

4. Ultrasound or Fluoroscopy

In some cases, ultrasound or fluoroscopy (real-time X-ray imaging) is used to assess how the oesophagus functions as the horse swallows.

5. Additional Tests

Blood tests may be performed to rule out neuromuscular or metabolic disorders that could contribute to the condition.

Treatment Options

There is no cure for megaesophagus, but careful management can improve the horse’s quality of life and reduce the risk of complications. Treatment focuses on supportive care, dietary adjustments, and managing secondary problems.

1. Feeding Management

Dietary modification is the cornerstone of managing megaesophagus:

• Feed sloppy mashes or soaked pelleted feeds to reduce the risk of choke.
• Avoid dry hay or large fibrous feeds that are difficult to swallow.
• Feed smaller, more frequent meals throughout the day.
• Offer food at chest height or slightly elevated, depending on veterinary advice, to help gravity assist swallowing.
• Ensure access to fresh water at all times.

Some horses benefit from grazing on lush pasture, where soft grass is easier to swallow and digest.

2. Preventing Choke

Because choke is a frequent complication, prevention is vital. All feed should be thoroughly soaked, and the horse should be fed in a calm environment without competition from others.

3. Treating Aspiration Pneumonia

If the horse inhales feed or saliva into the lungs, antibiotics, anti-inflammatories, and sometimes bronchodilators are necessary. Horses showing fever, coughing, or nasal discharge should be evaluated immediately.

4. Managing Oesophageal Injury

In cases where scarring or inflammation has contributed to the problem, your vet may recommend medications to reduce inflammation or promote healing, such as corticosteroids or sucralfate.

5. Addressing Underlying Causes

If an underlying disorder (for example, a neuromuscular disease or toxin exposure) is identified, treating that condition may help improve oesophageal function.

Prognosis

The prognosis for horses with megaesophagus depends on the underlying cause and the severity of oesophageal dysfunction.

• Foals with congenital megaesophagus often have a poor prognosis and may not survive long-term due to persistent regurgitation and pneumonia.
• Adult horses with acquired megaesophagus may live comfortably with proper management, especially if the condition is mild or secondary to an issue that can be corrected.

However, chronic cases can be challenging, and many horses require lifelong dietary adjustments. Recurrent aspiration pneumonia is a common cause of decline in affected horses.

Prevention

Because megaesophagus is often secondary to other conditions, prevention focuses on avoiding those risk factors:

• Treat choke promptly and avoid dry, coarse feeds.
• Maintain good dental care to ensure proper chewing.
• Provide adequate water at all times.
• Feed soaked or pelleted diets to older horses or those with dental issues.
• Monitor eating behaviour for early signs of difficulty swallowing or regurgitation.

Early detection and management of oesophageal problems greatly reduce the likelihood of long-term complications.

When to Call the Vet

You should contact your veterinarian if your horse shows:

• Repeated choke episodes
• Difficulty swallowing or frequent coughing after eating
• Nasal discharge containing feed material
• Unexplained weight loss despite a good appetite
• Signs of respiratory infection

Prompt veterinary attention can help diagnose the issue before permanent oesophageal damage occurs.

Conclusion

Megaesophagus in horses is an uncommon but serious disorder that affects the normal movement of food through the oesophagus. It can arise from congenital abnormalities, chronic choke, nerve damage, or scarring. Horses with this condition often experience repeated choke episodes, regurgitation, and weight loss, and are at constant risk of aspiration pneumonia.

While there is no cure, dedicated management, focused on soft feeds, frequent small meals, and careful monitoring, can allow some horses to live comfortably for many years. Understanding the condition, recognising early warning signs, and working closely with your veterinarian are the best ways to ensure your horse receives the care and support it needs.