“There will probably be an increase of blackleg this year because pastures are being grazed tighter this year, thus there is more exposure to soil where these bacteria may exist,” said Dr. Jeremy Powell, animal science associate professor and veterinarian at the University of Arkansas.
“Classic blackleg” is caused by an infectious bacteria Clostridium chauvoei. “This particular bacterium has a predilection or preference for muscle tissue,” said Dr. Doug Step, veterinary clinical sciences professor, and food and animal extension specialist at Oklahoma State University. “The bacteria will cause the release of toxins that result in destruction of muscle tissue. The toxins create pockets of gas within the muscle and under the skin.”
“This usually happens to calves that are 4 to 6 months old,” Powell said. “And it is usually seen in a calf that you think is a healthier calf. This can happen to older and younger calves, but usually happens to calves that are a few months old.”
For an individual animal, the usual sign that they have classic blackleg is immediate death. “Early recognition of affected cattle may include depression, lameness, decreased appetite, off by themselves, and fever,” Step said. “This may be treated if the producer notices the signs soon enough and they work with their veterinarian to administer proper antibiotics. Affected cattle may also require surgical intervention to remove the affected muscle tissues.”
According to Powell a common vaccination to prevent blackleg is a 7-way blackleg this vaccine creates antibodies for blackleg and other diseases that calves may be exposed to. This should be given to calves at 60 to 80 days of age, and again at weaning.
“We also give the cows in our university heard a vaccination of the 7-way before we turn them out for breeding every year. Cows will build immunity to provide colostrum which protects the calf from day one,” Powell said.
“Producers need to follow basic good husbandry practices, making sure their overall herd health is good and immunity is strong,” Step said. “Producers can do this by preventing over-crowding in facilities and when hauling livestock in trailers, and when working calves by making sure pathways and alley ways are clear of objects that may injure the animal; such as a broken board or panel along a fence line.”
It is important that producers work with their veterinarian to make sure a good health management plan is practiced so cattle immune systems are strong enough to withstand adverse environmental conditions, Step added. A veterinarian can also make sure calves are protected against the bacterial types for their specific location because the particular bacterial species and environments can vary across the state.
“Producers need to realize that the bacteria that can cause blackleg is everywhere in the environment,” Step said. “However, this summer there are additional conditions that lead to more possible cases of the bacteria infecting the calves. Drought causes animals to graze closer and since livestock are probably eating supplements as well, this provides an additional confined eating space. Confinement of the animal’s space can lead to more chances of bumps and bruises from other animals. The additional heat and dry weather also causes stress on the animals, environmental stress.”
