Megaesophagus Associated with Addison's Disease in a Dog

In the adult dog, most cases of megaesophagus are classified as idiopathic. acquired megaesophagus may be due to 1) neuromuscular disorders such as myasthenia gravis, SLE, and polymyositis/polymyopathy, 2) esophageal obstruction, 3) toxins such as lead and organophosphates, and 4) miscellaneous causes such as hypoadrenocorticism, hypothyroidism, esophagitis and thymoma.

This report describes a 5-year-old, neutered female Basset hound, presented with a 4 weeks’ history of lethargy, decreased appetite, weight loss and polyuria/polydipsia. a few days ago she vomited once. treatment with broad spectrum antibiotics had had no effect. routine laboratory examination revealed mild non-regenerative anemia, leuco- cytosis, hypoproteinemia and hypoalbuminemia. a thoracic radiograph, performed in the non-anesthetized dog, showed a megaesophagus.

Based on history, findings at physical exam, blood work and diagnostic imaging many causes of megaesophagus could be excluded or were considered less likely. additional diagnostics revealed no adrenocortical stimulation after aCtH administration and high basal plasma aCtH concentration, indicating addison’s disease. Within a few days after start of the treatment for addison’s disease the dog showed full clinical recovery; hematological and biochemical abnormalities were normal at 5 weeks after start of the therapy.

For the idiopathic form and some acquired forms of megaesophagus, treatment is only supportive and symptomatic. a risk factor is development of aspiration pneumonia, and this is the reason for the guarded to poor prognosis (1). although rare, addison’s disease has been reported as an underlying cause for megaesophagus (2-4). treatment of addi- son’s disease often results in disappearance of megaesophagus (2). therefore, dogs with megaesophagus should be screened for addison’s disease.