I heard it once said by an old vet long before me that “blackleg was a decent disease. It killed its patient before time and money was wasted on it”. Though this may be the case, blackleg remains an important differential in the cause of sudden death in cattle in Ireland.
Causes of Blackleg
Blackleg is caused by Clostridium Chauvoei a Gram positive spore forming anaerobic bacteria. They are found in the environment and are widely dispersed in soil and vegetative matter, whilst also serving as a commensal within the intestines of many ruminant species, and as such, spores can lay dormant for many years. It is worth noting that Chauvoei belongs to the same family of bacteria that cause, tetanus, blacks disease, malignant oedema and botulism to name a few. Not a nice bunch!
For an animal to get blackleg, there must be ingestion of spores that allows bacteria spread to the organs and muscle tissue. Here, they may lie dormant for a prolonged period of time, before a trigger factor initiates the onset of clinical disease. This trigger may be a bruise from a kick or bang going up a crush. It often strikes the best animal in the herd, because the more muscle dense the animal, the more favourable conditions arise for the bacteria following an injury.
Long before veterinary was on my mind, an uncle went from dairy to suckling. Black leg hadn’t been a thought on the farm for decades, but within two years of changing, and the increased musculature of the young stock, blackleg wiped three weanlings overnight.
Prevention of Blackleg
This year both vets in practice and the regional labs, both north and south, have noticed an increased incidence in blackleg, even in herds where historically it wasn’t thought to be an issue. Luckily there is a vaccine that cover others of the aforementioned members of the clostridial family. Vaccination should be started in young stock and a booster shot is essential, otherwise you’re relying on luck. Plan vaccination in advance for when to do and get the vaccine, as nowadays the modern supply chain has meant vaccine shortages are unfortunately more commonplace. Think of it as good earthing rod; it may never do anything or it could be doing a lot, but without it, it could be a disaster.
About the Author
Tadhg Gavin MVB DHH, Killaloe Veterinary
Tadhg qualified from UCD in 2010. Upon graduation, he worked in dairy practice in Kanturk before returning home to Co. Clare in 2015, to Killaloe Veterinary Clinic, where he runs the mixed practice. The practice joined XLVets Ireland in October 2019. Tadhg is the current chair of the XLVets Farm Animal Committee.
