Other foals develop extensive diffuse thickening of the duodenum and proximal jejunum. Foals with interference of pyloric outflow or duodenal flow exhibit signs of active ulceration except that gastro-esophageal reflux is more consistent and pronounced. All the classic signs of ulceration are present. Aspiration pneumonia may occur in these foals because of the volume of gastric reflux. Foals with ulcer-associated obstruction are usually three to five months old, and may present with dehydration, hypochloremia and moderate acidosis.
Prognosis is grave without surgical intervention.
Detection of a pyloric stricture via gastroscopy is highly subjective, and since it is near impossible to pass an endoscope into the duodenum, duodenal strictures are almost impossible to see. Contrast radiography demonstrates a flaccid esophagus filled with fluid that does not reach the stomach. If no contrast material fills the small intestine within 90 minutes of administration and there is an absense of distension of the small intestine, then duodenal stricture is likely. Differentiating a pyloric from a duodenal stricture based on pH of refluxed fluid is not reliable.