Megaesophagus in Dogs

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Overview of Canine Megaesophagus

Megaesophagus is a condition where there is decreased or absent motility (movement, muscular contractions) of the esophagus in dogs. The esophagus is the tube that carries food and water from the throat to the dog’s stomach. With megaesophagus, passing food all the way to the stomach becomes difficult, and the food may be regurgitated back up into the throat. This reduced motility usually results in dilation of the esophagus.

Megaesophagus may be present at birth and become apparent shortly after weaning, or it can be acquired later in life. It can be secondary to a variety of diseases that cause neuromuscular dysfunction, or it can occur as a primary disorder for which the cause is unknown (idiopathic). It may be associated with esophageal obstruction due to a foreign object, stricture or narrowing, neoplasia (cancer), compression from adjacent masses in the chest, or compression from a vascular ring anomaly (a congenital defect of the blood vessels in front of the heart).

Affected animals may have difficulty maintaining adequate nutrition due to their inability to move food into the gastrointestinal tract. They may also develop pneumonia secondary to regurgitation and aspiration of foodstuffs into the lungs.

Megaesophagus is seen in both dogs and cats; however, it is much more common in dogs. It is hereditary in the wirehaired fox terrier and miniature schnauzer. Other breeds commonly affected include the German shepherd dog, Newfoundland, Great Dane, Irish setter, Chinese shar-pei, pug, and greyhound.

What to Watch For

  • Regurgitation of food and water
  • Fever
  • Cough
  • Nasal discharge
  • Salivation
  • Sometimes difficulty swallowing
  • Foul odor to the breath
  • Weight loss
  • Poor body condition
  • Respiratory distress with severe aspiration pneumonia
  • Diagnosis of Megaesophagus in Dogs

    A thorough description of the clinical signs is very important and can often be the key to the diagnosis. It is most important that your veterinarian understands exactly what signs your pet is exhibiting at home. Diagnostic tests are necessary to confirm a diagnosis of megaesophagus. They may include:

  • Complete blood count (CBC)
  • Biochemical profile
  • Urinalysis
  • Thoracic X-rays
  • Acetylcholine receptor antibody titer
  • Antinuclear antibody (ANA) titer for immune-mediated diseases
  • Hormonal testing, such a an adrenal stimulation test and thyroid function tests
  • Blood lead level
  • Treatment for Megaesophagus in Dogs

    Treatment for megaesophagus is directed at the underlying disease or associated conditions. In the event no underlying cause is identified, symptomatic and supportive measures are recommended:

  • Drugs that help increase gastrointestinal motility or movement
  • Antibiotic and fluid therapy in cases of pneumonia secondary to megaesophagus
  • Home Care and Prevention for Megaesophagus in Dogs

    Administer any prescribed medications and feed your dog according to the instructions given to you by your veterinarian. It is critical that you follow any special feeding instructions to reduce the risk of aspiration of food or vomitus into the lungs. It is important to maintain adequate nutrition if at all possible.

    Most causes of megaesophagus cannot be prevented. However, megaesophagus associated with ingestion of certain types of foreign bodies or toxins may be prevented by closely monitoring your dog’s environment.

    Information In-depth for Megaesophagus in Dogs

    Because the history, physical examination findings and overall presentation of animals with megaesophagus are variable, there are other illnesses that must be ruled out when establishing a definitive diagnosis. It is important to note that regurgitation, which is the effortless evacuation of fluid, mucus, and undigested food from the esophagus, is the most common clinical sign associated with megaesophagus. Regurgitation must be differentiated from vomiting, which is the forceful evacuation of digested food from the stomach.

    The following are often associated with regurgitation:

  • Esophagitis – an inflammation of the esophagus
  • Foreign bodies that obstruct or block the esophagus
  • Esophageal neoplasia (cancer)
  • Hiatal hernia – an abnormality of the diaphragm that allows part of the stomach to be displaced into the thoracic (chest) cavity
  • Esophageal diverticula – a pouch-like dilatation or ballooning of the esophageal wall that can be present from birth or acquired secondary to esophageal weakness

    Megaesophagus may occur as a component of several systemic diseases, such as:

  • Myasthenia gravis – an immune disorder that causes fatigue of the muscular system and weakness
  • Polymyositis – an inflammation of many different muscles in the body
  • Systemic lupus erythematosus – an immune disorder that affects multiple body systems
  • Botulism – a type of food poisoning
  • Tetanus – a bacterial infection causing severe muscle spasms
  • Dysautonomia – an inflammation and degeneration of certain components of the autonomic nervous system
  • Endocrine diseases, including hypothyroidism and hypoadrenocorticism
  • Toxicity caused by exposure to lead, thallium, and organophosphate insecticides
  • Thymoma – a tumor arising from the thymus organ in the chest
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