Abstract
Fibrinopurulent peritonitis and abdominal abscesses associated with Streptococcus (S.) equi subsp. zooepidemicus is reported in a 1-year-old female thoroughbred horse. The horse died after showing 5-day history of the cold, severe abdominal distention, abdominal breathing, hyperthermia, anorexia, and loss of intestinal sound. At necropsy, several liters of turbid yellowish green fluid were seen in the abdominal cavity. Yellowish creamy and fibrinous or bloody materials were presented on the serosa of various abdominal organs that were intensively adhered with each other. Spleen and mesenteric lymph node were remarkably enlarged. Affected lobes of the lung showed severe congestion, hemorrhage and doughy consistency. Histologically, the lung showed hemorrhagic pneumonia with diffuse congestion and edema. Severe diffuse fibrinopurulent peritonitis with Gram-positive bacterial cocci and adjacent fibrosis were showed in the serosa of various abdominal organs such as liver, spleen, stomach, and intestine. And multifocal abscess pouches were presented in the granulation tissue of abdominal viscera. S. equi subsp. zooepidemicus was isolated from the peritoneal swab, abdominal organs, and lung. Hematogenous dissemination of bacteria from hemorrhagic pneumonia is proposed as the route of infection in this case.
