Esophageal diseases (Proceedings)

Esophageal diseases cause disturbance of food flow through the esophagus due to obstructions from foreign bodies and tumors, inflammation, decreased motility, and compression of the esophagus from intramural or extra-luminal masses. Esophageal diseases in the dog and cat can be very debilitating and require emergency treatment in many cases. Complications of esophageal disease can be life-threatening due to aspiration pneumonia, necrosis of the esophagus, strictures of the esophagus and severe malnutrition. Most esophageal diseases are treatable if diagnosed early and immediate treatment administered. Diagnosis of esophageal disease is usually not difficult although some patients require more expensive diagnostic tools such as fluoroscopy or endoscopy to diagnose the problem. Treatment is specific for each condition with obstructions and esophagitis being most treatable. Primary motility disorders and neoplasia of the esophagus have a poorer prognosis. In general, dogs present more frequently for esophageal diseases than cats however, overlooking the clinical signs of esophageal disease in cats may prevent proper diagnosis with feline patients possibly being under-diagnosed.

Clinical Signs of Esophageal Disease

Regurgitation is the hallmark sign of esophageal disease. It is distinguished from vomiting as being a passive process that contains undigested food in a tubular shape containing mucus and having a neutral Ph. No bile is seen in regurgitation due to the ingesta not reaching the stomach or small intestine. Regurgitation is similar to vomiting in that it can occur immediately after the patient eats or hours later. There is usually no retching or hypersalivation prior to regurgitation as there is with vomiting. Owners are not very good at distinguishing the two so the clinician must be very specific in asking questions to distinguish or to observe the patient during the process. A patient that has had esophageal disease for a period of time will have weight loss, muscle wasting, weakness, dehydration, malnourished, ravenous appetite is not a painful disease and possibly trouble swallowing. Coughing, dyspnea and pyrexia may be present if aspiration pneumonia is present.

Esophagitis/Esophageal Foreign Bodies/Esophageal Strictures

Esophagitis is usually the outcome of a primary insult to the esophagus such as a foreign body, gastric reflux and ingestion of caustic substances. Clinical signs differ from other esophageal problems in that this is a very painful condition. The patient is quite bothered by the problem and usually refuses to eat and drink. The patient may have increased swallowing, hypersalivation, dysphagia and regurgitation. Usually this is an acute onset however post-surgical gastric reflux may take a few days to cause clinical signs. The complication of esophagitis is stricture. Some patients recover from esophagitis only to present with regurgitation due to stricture. Strictures are not painful. Foreign bodies are most commonly seen in toy and small breeds with bones being over-represented causing obstructions. Other foreign bodies commonly found are fishhooks, sticks, balls and treats. Diagnosis of esophagitis is by endoscopic visualization. Usually thoracic radiographs, esophagrams and fluoroscopy are normal unless there is secondary decreased motility present. Foreign bodies usually are found on thoracic radiographs as most are opaque. Strictures are hard to find on radiographs with endoscopic exam required for diagnosis. Foreign bodies of the esophagus are emergencies and should be sent to a referral center with endoscopic capabilities immediately. Endoscopic retrieval of foreign bodies offers the best chance for recovery. Foreign bodies obstructing the esophagus over 24 hours have a high risk of causing severe necrosis that may perforate and/or lead to stricture. Surgical repair is indicated in these patients which has a poor prognosis due to the fibrotic healing that occurs and the high potential for dehiscense and stricture post-operatively. Treatment of esophagitis due to any cause consists of NPO for 2-3 days depending on the severity, hydrogen pump inhibitor drugs such as omeprazole (Prilosec) to reduce gastric acid (H-2 blockers are not as good at reducing gastric Ph) and prevent acidic reflux, a motility drug to increase the tone of the lower esophageal sphincter such as metoclopramide (Reglan) or cisapride (Propulsid) to prevent gastric reflux, liquid sucralfate (Carafate) to protect the exposed sub-mucosa of the esophagus from further insult by gastric acid and analgesics for pain control. Anti-inflammatory doses of corticosteroids may also be given to reduce fibrotic healing in an attempt to prevent strictures. Foreign bodies that are retrieved without perforation are treated as severe esophagitis patients as above after the endoscopic procedure. Severe esophagitis patients may need gastrostomy tube placement if not able to eat after 3 days. Nutrition is very important in the healing process. Intravenous fluids and intravenous broad-spectrum antibiotics are needed for fluid and electrolyte support as well as prevention of wound infection. Strictures are treated by balloon catheter dilation via endoscopic placement. Usually 2 to 3 balloon catheter dilation procedures separated by 5 days are needed to widen the stricture without causing perforation and allowing the stricture to widen enough to allow food to pass easily. Prognosis of esphagitis, esophageal foreign body and esophageal stricture depends on how soon the patient is treated and how severe the insult is to the esophagus. Endoscopic removal of foreign bodies and treatment of strictures can be cost prohibitive for some owners.

Megaesophagus

Megaesophagus (congenital and acquired)

Congenital

Esophageal hypomotility is suspected as the cause of congenital megaesophagus. Dogs by far present with this syndrome more commonly than cats. Some patients have hypomotility due to delayed maturation of esophageal function that may or may not improve with age. Congenital myasthenia gravis may cause congenital megaesophagus however congenital myasthenia gravis does not usually respond to treatment. Breeds predisposed to congenital megaesophagus are Newfoundlands, Jack Russell terriers, Samoyeds, Springer spaniels, smooth fox terrier and the Shar pei. Most puppies and kittens begin to show signs of regurgitation at weaning when they are started on solid food about 4 weeks of age. Diagnosis is by thoracic radiography and/or an esophagram (barium study) showing a diffusely dilated esophagus throughout the cervical and thoracic esophagus. Other congenital conditions such as vascular anomalies (persistant right aortic arch) can also cause megesophagus and diagnosis is made by visualizing a dilated esophagus cranial to the heart with thoracic radiographs, esophagram and sometimes thoracic ultrasound with arterial contrast can be helpful. Surgical correction of this condition can be successful if done early enough to prevent permanent megaesophagus from the esophagus being compromised for a long period of time.

Acquired

Most patients with acquired megaesophagus are idiopathic with no underlying cause identified. Mostly this disease is seen in the dog although the cat with dysautonomia syndrome can present with megaesophagus. Although the exact etiology of acquired megaesophagus is unknown it is suspected that there is a defect in the afferent neural pathway causing reduced responsiveness of the esophagus to distention thereby limiting peristaltic contraction. Most patients present as adults although acquired forms can occur in the young. Acquired megaesophagus with primary causes include acquired myasthenia gravis, hypothyroidism, hypoadrenocorticism, neuromuscular disorders such as botulism, polymyositis, polyradiculoneuritis, dysautonomia, bilateral vagal nerve damage, brainstem disease, lead toxicity and organophosphate toxicity. The most common and most treatable primary causes of acquired megaesophagus are acquired myasthenia gravis, hypoadrenocorticism and hypothyroidism. In all cases of acquired megaesophagus these diseases should be investigated with proper diagnostics to rule out a treatable condition. Diagnosis of acquired megaesophagus is thoracic radiograph and/or esophagram showing a diffusely dilated esophagus throughout the cervical and thoracic esophagus. Further diagnostic tests should include basic bloodwork (CBC, chemistry panel) and testing for myasthenia gravis (acetylcholinesterase receptor antibodies), hypoadrenocorticism (ACTH stimulation test) and hypothyroidism (TSH, TT4, FT4).

Treatment of Congenital and Acquired Megaesophagus

A common complication of megaesophagus is aspiration pneumonia due to frequent regurgitation of food and water. Aspiration pneumonia should be treated aggressively with intravenous broad-spectrum antibiotics, intravenous fluid therapy, nebulization and coupage. Megaesophagus without a primary cause is treated with elevated feedings of either gruel or meatball consistency of canned food giving small amounts frequently depending on the individual patient response and holding the dog in an upright position for 15 minutes after each feeding. Severe cases that regurgitate in spite of these feedings can have a permanent low profile gastrotomy tube placed and used for the rest of the dogs life. The most common cause of death in these patients is repeated aspiration pneumonia and owner request for euthanasia.

Esophageal Neoplasia

Although very rare, esophageal neoplasia occurs occasionally in dogs and cats. Squamous cell carcinoma, leiomyoma/leiomyosarcoma, metastatic thyroid carcinoma and fibrosarcoma secondary to Spirocerca lupi have been reported. Clinical signs of esophageal obstruction are present and may occur progressively with the patient presenting with severe weight loss and malnutrition. Diagnosis is by thoracic radiographs, esophagram and endoscopic biopsy. Surgical resection of the tumor and radiation therapy can be considered but overall the prognosis is very poor for long term.

Esophageal Abscess or Granuloma

Esophageal abscess or granulomas have been reported secondary to Spirocerca lupi and are treated with antibiotics, drainage by surgery and anthelmintics.

Peri-esophageal Mass

Extraluminal compression of the esophagus can occur due to an anterior mediastinal lymphosarcoma, thymoma, heart base tumor and thyroid carcinoma. Diagnosis is made by thoracic radiographs, thoracic ultrasound, CT scan and potentially a fine needle aspirate or tissue biopsy. Treatment with chemotherapy, surgery or radiation therapy may be indicated.

Esophageal Motility Dysfunction (without obvious megaesophagus)

Esophageal motility dysfunction can be present without an obvious air or food-filled, dilated esophagus on a thoracic radiograph. The esophagus can be normal in shape and size and empty. Fluoroscopy is best in identifying these mild cases. Usual cause of transient motility dysfunction is usually due to esophagitis secondary to vomiting or gastric acid reflux. Treatment for the underlying cause and megaesophagus until the problem resolves is indicated.