Wet weather can increase the incidence of blackleg in cattle, says Dr. Daniel Cummings with Boehringer Ingelheim. Blackleg is caused by a bacterium in the Clostridium family. All of the bacteria in this species can cause serious illness in many different animals, and blackleg is no exception.
Blackleg is almost always a deadly disease that can increase after flooding or if dirt work or excavating has been done on the farm. This allows the clostridial spores to rise to the top of the ground and be ingested by cattle. Outbreaks can also occur after long dry periods followed by heavy rainfall. Many times clinical signs are not noted and the cattle are simply found dead, but sometimes you will notice a lethargic and limping calf. The disease usually occurs in cattle 6-18 months of age but I have seen calves as young as 4 months and adults also affected, especially in outbreak situations. Because the disease causes such rapid death, treatment is unlikely to be effective but large doses of penicillin have been effective in rare cases. Any calf that dies unexpectedly should be examined by your vet to determine the cause of death. Calves with blackleg will sometimes have gas under their skin and a crackling feel can be noted as you rub your hands along the calf’s skin immediately after death. However, many dead calves can have this feel several hours after death.
The most important thing to do is prevent the disease as a very effective vaccine is available. All calves in Texas should be vaccinated when they are over 3 months old. If you have a history of blackleg on your ranch, then it’s a good idea to vaccinate prior to 3 months and then vaccinate again after 3 months.