Blackleg, black quarter, quarter evil, or quarter ill (Latin: gangraena emphysematosa) is an infectious bacterial disease most commonly caused by Clostridium chauvoei, a Gram-positive bacterial species.
It is seen in livestock all over the world, usually affecting cattle, sheep, and goats. It has been seen occasionally in farmed bison and deer.
The acute nature of the disease makes successful treatment difficult, and the efficacy of the commonly used vaccine is disputed.
Most losses due to blackleg occur when the cattle are between the ages of six months and two years, although it can occur when they are as young as two months.
Typically, cattle that have a high feed intake and are well-conditioned tend to be the most susceptible to blackleg.
Blackleg is caused by infection with Clostridium bacteria.
The most common causative agent is
▪C.chauvoei, but the disease can also be caused by
▪C. sordelli, and
When infection begins, the animal may develop a fever, and the affected limb can feel hot to the touch. The limb usually swells significantly, and the animal can develop lameness on the affected leg.
Crepitation (the sensation of air under the skin) can be noticed in many infections, as the area seems to crackle under pressure.
During a necropsy, a diagnosis is usually made very quickly, as the affected muscle is usually mottled with black patches, which are dead tissue killed by the toxins the bacteria release when they infect live tissue.
Vaccination and prevention:
The use of a seven-way clostridial vaccination is the most common and cost effective preventative measure taken against blackleg, but its efficacy is disputed.
Burning the upper layer of soil to eradicate left-over spores is the best way to stop the spread of blackleg from diseased cattle.
Diseased cattle should be isolated. Treatment is generally unrewarding due to the rapid progression of the disease, but penicillin is the drug of choice for treatment. Treatment is only effective in the early stages and as a control measure.