Hemorrhagic fibrinonecrotic duodenitis-proximal jejunitis in horses: 20 cases (1977-1984).

Records of 20 horses with small intestinal disease causing acute colic and affecting the proximal portion of the small intestine were examined retrospectively. The disease was characterized by severe to moderate pain, which was replaced by depression, fever, gastric reflux, slight distention of the affected small intestine, leukocytosis, and high concentrations of total protein in the peritoneal fluid. Grossly, the affected intestines were hemorrhagic and had yellow discoloration. Histopathologic findings included submucosal edema, neutrophilic infiltration of the submucosal and laminal propria, and mucosal slough at the villous tips. Advanced lesions were characterized by mucosal sloughing with transmural edema, hemorrhage, fibrin deposition, and necrosis. No cause was determined. In 6 horses, bypass of most of the affected small intestine was helpful by alleviating the severe gastric reflux.