Figure 4

Pathological findings in brown bear 40 showing clostridial gangrenous myositis due to Clostridium novyi. A Humerus. Fractures of the head of the left humerus are shown. B Skeletal muscle. Serohemorrhagic edema, emphysema and hemorrhages are observed in skeletal muscles, mainly affecting the longissimus dorsi and iliocostalis lumborum. C Adipose tissue. Vascular damage with loss of endothelial cells and thrombus formed by clostridial-like bacilli are observed in the lumen of the vessels. Hematoxylin and eosin stain. D Adipose tissue. Thrombi formed by Gram positive clostridial-like bacilli are observed in the lumen of the vessels. Note that bacteria are invading the endothelium. Gram stain. E) Iliocostalis lumborum skeletal muscle. Hyperacute myodegeneration consisted of myonecrosis (arrowhead), edema, gas (asterisk), extravasation of fibrin into the interstitial spaces and lacunar dissolution of myofibers can be observed. Hematoxylin and eosin stain. F) Iliocostalis lumborum skeletal muscle. Numerous Gram positive clostridial-like bacilli are present, mainly located in the interstitial space. Gram stain.