The recent outbreaks of the clostridial disease, blackleg, in cattle is generating more discussions in the industry as to the possible risks of other clostridial diseases.

The fact that many of the outbreaks have not been typical of a sporadic case or two of mortality and have manifested in significant outbreaks is fuelling greater concern.

Blackleg can occur in sheep and has been identified on occasion in veterinary laboratories.

The recent outbreaks have been confined to cattle with no spike seen in sheep. There have, however, been significant cases of other clostridial diseases causing mortality in sheep.

The clostridial disease strain possibly presenting the greatest challenge at present and also in recent months is pulpy kidney.

The bacterium that causes the disease, C. perfringens, is normally present in the intestinal tract of animals with the disease typically manifesting due to environmental conditions.

Greatest risk

For example, it is most commonly seen in young rapidly growing lambs and lambs that are consuming starchy diets/on an intensive diet.

The other timeframe often triggering a spike in cases is a marked dietary change, such as concentrate supplementation commencing or lambs housed for finishing.

There are few warning signals with sudden death the most common clinical sign.

Where animals are found alive, the expression of neurological issues and depression are common clinical symptoms. As such, it is important that any sudden or unexplained deaths are investigated.

There is often a spike at this stage of the year as maternally derived antibodies are absent and animals transfer on to finishing diets.

Farm specific

While the bacteria linked to different strains of clostridial disease are found in most environments, the occurrence of disease varies greatly.

Some farmers have never knowingly experienced problems while others are exposed to high levels of mortality in the absence of vaccination programmes.

It is most commonly seen in young rapidly growing lambs.

Environmental changes are common stress factors while bringing naïve animals on to a farm where issues have traditionally been prevalent can also lead to significant mortality.

It is up to each farmer to weigh up the risks and cost-benefit analysis of vaccination.

Where there is any history of issues then vaccination is top of the list in flock health plans.

Vaccine efficacy

There are a number of practices that greatly influence the success of vaccination.

  • Administering the full primary course: two vaccinations are required to allow animals to develop full immunity. With most products, this is typically administered four to six weeks apart. One vaccination will provide limited treatment and may be useful where lambs are being transferred on to a short-term intensive finishing diet but for longer-term retention and replacements, two vaccinations are vital.
  • Correct volume: administering a lower volume than recommended is a false economy. While it may lower the cost per head, it prohibits animals from developing full protection. Ensure your injection gun is working adequately and is calibrated regularly.
  • Adequate storage: vaccines are sensitive to temperature changes and must be stored and handled as per the manufacturer’s instructions.
  • Product selection: products on the market typically cover eight to 10 strains of clostridial disease with some products also offering protection for pasteurella. Select a product that best addresses the risk factors for your farm.
  • Administration techniques: adequate time should be taken to ensure the vaccine is delivered hygienically as per the manufacturer’s guidelines.

    • Scheme delivery

    Clostridial disease vaccination was included as an action in the 2024 Sheep Welfare Scheme.

    Where the required number of ewes were vaccinated in 2024 (booster or full course) then the action is deemed to be completed.

    Where ewes were not vaccinated and, as such, the action is being carried out on lambs then take note that lambs must receive a full course consisting of two vaccinations.

  • The recent outbreaks of blackleg have been confined to cattle.
  • Sheep remain at risk to clostridial diseases with current variable weather and changing practices possible stressors.
  • Numerous factors can influence the success of vaccination programmes.