Acute hemorrhagic diarrhea syndrome (AHDS), formerly termed hemorrhagic gastroenteritis (HGE), is an acute condition of unknown cause characterized by severe hemorrhagic diarrhea and vomiting. AHDS typically affects young to middle-age, small-breed dogs¹ and can lead to cardiovascular collapse and death without early aggressive therapy. Recovery is often rapid and complete with appropriate symptomatic treatment.

Endoscopic evaluation of affected dogs reveals no macroscopic or histologic gastric pathology, despite a high incidence of vomiting and hematemesis in many patients.^1,2 Severe, coagulative necrosis of the small and large intestines² is present histologically, however, and HGE was renamed AHDS following these findings.²

Clinical Signs

AHDS is characterized by peracute onset of vomiting, followed by lethargy, anorexia, hematemesis, and large volumes of malodorous hemorrhagic diarrhea.¹ In a prospective study of 108 dogs with AHDS, diarrhea occurred a median of 10.5 hours after the onset of vomiting.¹

Dogs with AHDS have severe mucosal necrosis and minor neutrophilic infiltrate of the small and large intestines, resulting in secretory and malabsorptive diarrhea.² Transudation of water, electrolytes, and protein, and disrupted sodium transport mechanisms leads to significant fluid loss.³ Subsequent hypovolemia and dehydration occur early during the disease.