A recent outbreak of blackleg disease among cattle has caused concern among farmers and veterinarians around the country.

Blackleg is an infectious clostridial disease that is caused by organisms in soil spores and is common in cattle, sheep and goats.

Farmers are recommended to contact their vet for treatment advice and to vaccinate consistently.

The Department of Agriculture responded to questions from the Irish Farmers Journal about the recent outbreak of blackleg.

Q. What counties have the increased levels of blackleg been identified in?

A. Most of the current reports are from the southern half of the country, but that is likely to merely reflect livestock density patterns rather than any geographical pattern or regional risk factor.

Q. How many animals or carcases have been diagnosed with the disease to date this year?

A. If we define an outbreak as ‘at least one death’, there have been 29 outbreaks between 1 April and 8 August 2024.

There are further unconfirmed cases under test submitted in early August.

The Department of Agriculture does not have a record of the number of animals that die from blackleg, this information is based on voluntary submissions by farmers to Department regional veterinary laboratories.

Feedback from farmers, and their veterinary practitioners, at the time of carcase submission was that these animals were one of a number of animals lost. This is significantly different to the usual pattern where outbreaks consist of a single animal death.

Q. How does this compare with last year?

A. There were 32 cases confirmed between April and August in 2023. However, July 2024 this year had four more cases than last year and if the high amount in the first eight days of August continues, this month would greatly surpass last year’s August figure.

Q. What factors do the Department think are at play for the increase in cases?

A. While the factors causing these outbreaks are unclear, anything that brings soil to the surface or increases contact with soil on pasture is a potential risk factor, such as excavation, drain clearing, etc.

There is a recognised association between blackleg outbreaks and heavy rainfall, but the mechanism is unclear. One hypothesis is that the buoyant clostridial spores are brought up to the surface in saturated or flooded pasture.

Another possibility is that there is greater soil exposure through vehicles or animals disrupting the pasture surface (‘poaching’), exposing bare soil and increasing the animals’ skin contact with soil.

Grazing animals will also take in more soil in their diet at pasture when the ground is saturated.