Blackleg

Blackleg (blackquarter, clostridial myositis) is an infectious disease of cattle and rarely of other ruminants, caused by Clostridium chauvoei and characterized mainly by necrotizing myositis. This chapter discusses the etiology, epidemiology, pathogenesis, clinical signs, diagnosis, prevention and treatment, of blackleg. Blackleg mainly affects cattle between 6 months and 2 years of age that are in good nutritional condition. Occasionally, cases in animals outside this age range may occur. The classical model states that the pathogenesis of this disease starts with ingestion of spores of C. chauvoei, which sometimes may undergo one or more replication cycles in the intestine before being absorbed into the bloodstream. Most cases of blackleg are acute or sub-acute, although chronic cases may occasionally occur. Carcasses of animals dying of blackleg are usually in very good nutritional condition. Vaccination is the most important method currently available to prevent blackleg and pseudoblackleg.