Megaesophagus is a disorder that commonly causes regurgitation in dogs. Cats are rarely affected. Characteristics include esophageal dilation and ineffective esophageal peristalsis. Normal esophageal peristalsis involves the sequential contraction of circular muscle required to push ingested food to the stomach. Megaesophagus shows reduced or absent motility as in movement or muscle contractions of the esophagus. This disorder causes symptoms to occur several minutes to hours after eating and results in regurgitation of food and water. Canines can suffer from malnutrition and aspiration pneumonia.
Several forms of Megaesophagus exist: congenital idiopathic, acquired idiopathic and acquired secondary Megaesophagus. Congenital idiopathic Megaesophagus involves generalized dilation of the esophagus. Hypomotility results in regurgitation. Afflicted puppies may not survive after weaning. Susceptible breeds include Irish Setter, Greyhound, Great Dane, German Shepherd, Labrador Retriever, Pug, Chinese Shar-Pei and Newfoundland breeds. This disorder is hereditary in Wirehaired Fox Terrier and Miniature Schnauzer.
Acquired idiopathic Megaesophagus affects adult dogs between seven and fifteen years old. Acquired secondary Megaesophagus may be associated with other conditions that cause neuromuscular dysfunction.
Symptoms and Diagnosis
Symptoms of Megaesophagus include regurgitation of food and water. Following feeding, regurgitation may occur several minutes to several hours later. Episodes may vary from every few days to many per day. Note that regurgitation is different from vomiting. Other signs include fever, cough, nasal discharge, mucus, salivation, difficulty swallowing, weight loss, poor physical condition. Dogs suffering from Megaesophagus can experience malnutrition and aspiration pneumonia.
Diagnosis should rule out other illnesses. Observations include excessive salivation, and mild to moderate cachexia (physical wasting from loss of weight, muscle atrophy, loss of appetite, etc.), coughing and wheezing.
The veterinarian may order routine hematology, serum biochemistry and urinalysis. Consideration of secondary causes such as hypothyroidism and hypoadrenocorticism should be taken into account. Survey radiographs, thoracic x-rays can help diagnose. Hormonal testing, an adrenal stimulation test and a thyroid function test may also help determine.
With each case of Megaesophagus being different, treatment follows specific recommendations. A high calorie diet may involve small feedings frequently per day. Dogs may be in an elevated or upright position to allow gravity drainage. Medium and large canines can place their front legs on a table for this position. Diet consistency is key. While some dogs adapt to a liquid diet, others improve more with a solid diet.
A feeding tube can benefit the patient that cannot take in an adequate nutritional balance orally. A gastrostomy tube may be temporary or permanent. A veterinarian can place the tube surgically or with the help of an endoscope.
Pulmonary infections can receive antibiotic treatment. The veterinarian may apply a transtracheal wash or bronchoalveolar lavage.
Congenital idiopathic Megaesophagus has a fair prognosis. Attention must be directed to diet management and prevention of aspiration pneumonia. Over several months esophageal motility can improve. Canines may undergo months of physiotherapy.
Acquired idiopathic Megaesophagus can result in a high morbidity and mortality. Chronic malnutrition and recurring aspiration pneumonia can claim the dog’s life.