Introduction

• Cause: developmental abnormality of vessels.
• Esophageal dilation cranial to base of heart in puppies and kittens.
• Most common (95%) - persistent right aortic arch (PRAA).
• Less common - double aortic arches, anomalous subclavian arteries.
• Signs: regurgitation on weaning, voracious appetite, aspiration pneumonia, smaller than litter mates.
• Diagnosis: signs, radiography, endoscopy.
• Treatment: aggressive supportive therapy and surgical correction of anomaly.
• Prognosis: depends on degree of megaesophagus.
• Usually no cardiovascular signs.

Pathogenesis

Etiology

• Congenital: persistent right aortic arch (stricture caused by ligamentum or ductus arteriosus, pulmonary artery and dextraposed aorta), double aortic arches, anomalous subclavian arteries.

Predisposing factors

• Breed, ?inherited congenital defect.

Specific

• Clinical signs exacerbated by feeding solid or semi-solid foods.

Pathophysiology

• Aberrant embryological development of great vessels at the heart base → esophagus encircled at the heart base by a right aortic arch, a ligamentum arteriosum (or patent ductus arteriosus) and the pulmonary trunk → accumulating food boluses proximal to vascular ring → esophageal dilation and eventual loss of function (megaesophagus) → typical signs of megaesophagus Megaesophagus.
• Frequent regurgitation attempts may cause gastric acid reflux and esophagitis distal to the vascular ring.
• Fibrosis may occur affecting adventitia around esophagus at site of vascular ring → esophageal stenosis.
• Aspiration pneumonia is a common complication.

Timecourse

• From weaning until successful correction.
• Life-long management may be necessary if megaesophagus occurs before surgery Megaesophagus.

Diagnosis

Treatment

Prevention

Outcomes