Disorders of the Esophagus in Dogs
Signs of problems with the esophagus include difficulty swallowing and regurgitation (return of food or liquid before it has reached the stomach). Regurgitation is effortless and has few warning signs, in contrast to vomiting which is an active process preceded by signs of nausea.
Congenital abnormalities of the esophagus (those present at birth) are discussed earlier in this chapter (see Congenital and Inherited Disorders of the Digestive System of Dogs : Esophagus).
The cricopharyngeal muscle opens and closes to allow food and liquids from the mouth into the esophagus. Cricopharyngeal achalasia is a condition in which this muscle does not adequately relax. This can lead to an inability to swallow foods or liquids. Though it is usually an inherited defect, adult dogs can also develop the condition. A dog will try to swallow and end up gagging and vomiting. A common complication of this disorder is aspiration pneumonia: liquids that a dog tries to swallow can end up going down the trachea and to the lungs. The cause is usually unknown, but it may be associated with neuromuscular disorders in adult dogs.
Treatment of this condition usually involves surgery to cut the abnormal muscle. Normal swallowing is usually possible immediately after the surgery. About 70% of the surgeries are successful. Dogs that have other neuromuscular disorders are less responsive to surgery, but may respond to treatment with successful management of the neuromuscular disorder. If the dog develops aspiration pneumonia, it must be treated immediately and aggressively.
Abnormal dilation or stretching of the esophagus (also called megaesophagus) can be caused by a congenital defect (see Congenital and Inherited Disorders of the Digestive System of Dogs : Esophagus), or it can occur in an adult dog, either alone or together with other diseases. Congenital megaesophagus (generally diagnosed in dogs soon after weaning) is a hereditary defect that occurs in Wire-haired Fox Terriers and Miniature Schnauzers. A tendency to occur in families has been reported in German Shepherds, Newfoundlands, Great Danes, Irish Setters, Chinese Shar-Peis, Greyhounds, and cats. Some causes of megaesophagus include myasthenia gravis, systemic lupus erythematosus, polymyositis, hypoadrenocorticism, lead poisoning, dysautonomia, nervous system disorders including cancer, and possibly hypothyroidism. Megaesophagus can also occur as a result of injury of the esophagus, the presence of a foreign object in the esophagus, or compression of the esophagus.
The primary sign of megaesophagus is regurgitation. Dogs with megaesophagus will suddenly start regurgitating undigested food soon after eating and will lose weight. Respiratory signs such as coughing and difficulty breathing may occur. A chest x-ray will show air, fluid, or food in the distended esophagus. Other tests may also be performed to view the esophagus and determine the cause and extent of the enlargement.
If an associated disease is causing megaesophagus, it must be treated. Surgery is often needed to correct blood vessel abnormalities. There is no specific medical treatment for megaesophagus with no known cause, but it may be managed by feeding the dog with the upper body in an elevated position of at least 45 degrees. Allowing the dog to eat in this position—by having the dog stand on a ramp or with its front legs on a platform with the food bowl higher—has been found to help. Keeping the dog in this position for at least 15 minutes after eating allows gravity to help the food move down the esophagus.
Changing the texture of the dog’s diet is usually necessary. The type of food that will best prevent vomiting varies from dog to dog. Soft gruel might work for some dogs, and others might do best with dry or canned foods. Feeding the dog in frequent small meals is usually helpful. The food should be high in calories to help the dog maintain its weight.
The overall outlook for dogs with this condition is guarded. Sixty per cent of dogs with megaesophagus tend to develop aspiration pneumonia or fibrosis of the lungs due to recurrent pneumonia, which may shorten their lifespan.
Esophageal stricture is a narrowing of the esophagus. It may develop after trauma (for example, ingestion of a foreign object or caustic substance), inflammation of the esophagus, gastroesophageal reflux (gastric acid flowing back into the esophagus), or tumor invasion. Signs include regurgitation, excessive drooling, difficulty swallowing, and pain. Examining the esophagus using fluoroscopy or endoscopy are the preferred methods for diagnosis. These tests enable your veterinarian to actually see the number, location, and types of strictures.
Treatment of the stricture by stretching it with a balloon catheter has been successful. The catheter is a tube that is placed in the esophagus and then advanced to where the stricture occurs. The tip of the catheter is then inflated like a balloon, which stretches the esophagus and relieves the stricture. Other methods, including surgery, have been less successful.
Inflammation of the esophagus is usually caused by foreign objects or acid reflux from the stomach into the esophagus. Occasionally certain drugs, cancer, or caustic substances will cause this condition. In many cases, a veterinarian will use an endoscope (a flexible tube with a tiny camera at one end) to explore the esophagus, search for foreign objects, and assess the extent of tissue damage.
Mild inflammation may produce no visible signs and often requires no treatment. If signs are present, drugs may be prescribed. For example, if the problem is caused by acid reflux (a cause of heartburn in people), drugs that reduce stomach acid can provide relief for your pet. Other prescription medications increase muscle tone in the lower esophagus, reducing the amount of acid that escapes upward. Your veterinarian may recommend feeding your pet a diet of soft food, low in fat and fiber, in small, frequent meals. If inflammation is severe, a feeding tube placed through the body wall into the stomach, bypassing the esophagus, may need to be inserted to allow the esophagus to rest. Antibiotics are sometimes prescribed to prevent bacterial infection.
Because of their eating habits, foreign objects in the esophagus are more common in dogs than in cats. Bones are the most common, but needles, fishhooks, wood, rawhide pieces, and other objects may also become lodged in the esophagus. Sudden and excessive drooling, gagging, regurgitation, and repeated attempts to swallow are signs of an esophageal foreign object. A partial obstruction may allow fluids but not food to pass. If an obstruction is not treated, loss of appetite, weight loss, and lethargy may occur. In addition, the foreign object can perforate the esophagus, which may require surgery. An esophageal stricture, which is a narrowing of the width of the esophagus (see Disorders of the Esophagus in Dogs : Esophageal Strictures), is the most common complication of an esophageal foreign object. Aspiration pneumonia may also be seen if regurgitated material is inhaled into the lungs.
Many foreign objects can be seen on x‑rays. In some cases, a contrast esophagram (a specialized test in which a dye that shows up on x-rays is swallowed) or esophagoscopy (examination of the esophagus with an endoscope) is needed. If a foreign object is detected in the esophagus, it should be removed immediately. Removal will depend on the object and on its current location. In many cases, your veterinarian will be able to remove the foreign object through the dog’s mouth, using a flexible endoscope and forceps (large tweezers) or other instrument. If the object cannot be removed by mouth, sometimes it can be pushed into the stomach where it can be digested and passed in the feces, or removed via surgery. Surgery is necessary if the esophagus has been perforated or the foreign object cannot be removed using endoscopy; in these cases, the overall recovery rate has been reported to be greater than 90%.
Diverticula are pouch-like expansions (dilations) of the esophageal wall. They can be inherited or acquired. They are rare in dogs. Small diverticula may cause no signs. Large diverticula can trap food in the pouch, causing the dog to have trouble breathing after eating, vomit, or stop eating. Contrast x-rays can be used to diagnose the disorder. Endoscopy (using a tiny video camera in a flexible fiber optic tube) can allow the veterinarian to see the actual pouch and any ulceration or scarring that may be present.
Small diverticula can usually be treated with a bland, soft food diet. The animal should also eat in an upright position (having the forelegs raised higher than the hindlegs, such as on a ramp or platform, and holding this position for a short period of time after eating). Large diverticula require surgery involving removal of the pouch and rebuilding of the esophageal wall. The outlook for recovery after surgery is guarded to fair.