Caudal esophageal achalasia in a Quarter Horse colt.

Achalasia is the most common motility disorder of the esophagus in humans and has been diagnosed in cats and dogs. We describe a 4-month-old Quarter Horse colt with failure to thrive, recurrent colic episodes, and aspiration pneumonia, in which fluoroscopic evaluation identified a caudal esophageal motility disorder consistent with achalasia. Necropsy examination confirmed achalasia.