This document discusses the genus Clostridium, including C. novyi which causes several diseases in livestock. C. novyi type A causes swollen head syndrome in sheep and goats, characterized by edema around the eyes, face and neck. Left untreated it is lethal. C. novyi type B causes black disease or necrotic hepatitis in sheep, which progresses rapidly and can kill animals within 4-6 hours. It causes necrosis in the liver. Vaccines include toxoids and cultures of C. chauvoei, C. perfringens types C and D, C. septicum, C. novyi, and C. sordelli to help prevent these diseases.