AFBI’s animal disease surveillance service has detected a number of cases of blackleg in post-mortem submissions over recent weeks and we wish to advise farmers of the need to vaccinate against what is a preventable disease.
Blackleg is an important disease of cattle, particularly between the ages of 6 months to 2 years. The disease is caused by the bacterium Clostridium chauveoi.
The bug is a rod shaped organism that is present in the soil and is highly resistant.
Blackleg is most common in animals when they are outdoors however there have been cases diagnosed in housed animals.
The condition is nearly always fatal. It is caused by the activation of dormant Clostridium chauveoi spores which have been ingested by cattle and sheep previously and remain within the muscles. When conditions are ideal for the organism, for example when muscle is damaged the spores undergo activation, the bacteria multiply and produce a potent substance known as a toxin that results in the characteristic muscle lesions and typical carcase changes before death.
Due to the severe nature of the disease there is often no opportunity for treatment with the affected animal dying within 24 hours of the onset and often submitted to the post mortem room with a history of sudden death. Diagnosis involves culture of the bacterium and fluorescent antibody testing and muscle tissue can be examined for typical lesions under the microscope. Lesions are typically found in the large muscles of the legs, muscles over chest or pelvic muscles as well as the diaphragm, tongue, or heart.
Clostridial vaccines are relatively inexpensive and highly effective in preventing occurrence of the disease and we advise all cattle farmers to discuss vaccination regimes with their private veterinary practitioner. Farmers should also consult their vet immediately in cases when Blackleg is suspected and advice sought on both on diagnosis of the suspected case and possible preventive actions.