Fatal Peritonitis associated with Pasteurella multocida in an Asian Small-Clawed Otter (Aonyx cinereus)

A 12-year-old female small-clawed Asian otter (Anoyx cinereus) with a one-week history of anorexia, chills, and abdominal distension was found dead.Grossly, yellowish-brown turbid fluids accumulated in abdominal cavity of the otter, and yellowish thread-like fibrinous materials were found on the surface of abdominal organs.Several variable sized yellowish-white crystalloids were scattered on the medullary space of kidneys.Histologically, diffuse serositis (peritonitis) characterized by the fibrinous exudates, thickened serosal capsule and the swelling of mesothelial cells were observed in the serosa of liver, spleen, stomach, and intestine.Multifocal necrosis, hemorrhage, infiltration of macrophage, and brown pigments were presented in the liver.Isolated bacteria from ascites and fibrinous materials in abdominal visceral surface were white, smooth and convex with characteristic mousy odor on blood agar plate.These bacteria were confirmed as Pasteurella (P.) multocida type A by polymerase chain reaction analysis.Based on the gross examination, histopathologic findings and bacterial experiments, this otter was diagnosed as severe peritonitis associated with P. multocida and necrotic hepatitis.