Blackleg is an acute febrile noncontagious infection of deer, cattle, sheep and pigs, characterized by sudden onset, fever and emphysematous serohemorrhagic swellings in the subcutaneous tissues and heavy musculature. Death usually occurs within 24 hours.
Animals of all ages in all parts of the world may be affected by the disease but young animals between the ages of 6 months and 2 years are particularly susceptible. The blackleg bacillus is one of the anaerobic bacteria which only grow in the absence of oxygen. It forms spores which are highly resistant to soil and which lodge in the intestinal tracts of animals. Infection may occur through contaminated wounds, particularly small punctures made by thorns or barbed wire.