Clostridial Disease in Sheep

Clostridial diseases almost always result in death and may often involve a significant number of animals in a sheep flock.

The common diseases are:

• Pulpy Kidney (PK, enterotoxaemia): Classical signs are sudden death in young lambs that are well fed and growing quickly. Can affect animals at any age, especially when they are grazing high quality pastures (eg. flushing ewes, hoggets on spring pastures).
• Tetanus: Occurs when tetanus spores enter deep wounds where there is minimal aeration and dead & damaged tissue. Most common after docking. Risk is greater with rubber rings and when the searing iron is not hot enough causing excessive deep tissue damage to allow the tetanus spores to proliferate.

The next 3 diseases are similar in appearance and all fall into the blood poisoning category which is typified by sudden death followed by going off quickly, bloody discharge from nose, and bloating.

• Blackleg: Usually associated with dirty wounds, grazing muddy winter feed crops, after lambing, and using dirty vaccination needles.
• Malignant oedema: Lesions very similar to blackleg.
• Black disease: Usually associated with liver fluke infection.

Signs and Symptoms

Tetanus usually appears 10-14 days after the injury (e.g. docking wounds, shearing wounds). Animals are stiff and go into a rigid spasm if stimulated. They look as if they are smiling due to contraction of the facial muscles. Dead animals look normal.

Animals with PK are usually only found dead with no outward signs. Postmortem may help, but no vaccination, lambs doing very well, and very sudden death are classical.

Animals with blood poisoning are usually found dead. “Go off” very quickly. There may be gas under the skin.

The Impact.

All the common clostridial bacteria are almost endemic throughout NZ farms, the diseases are, however, relatively uncommon due to the widespread use of vaccination. Because vaccination is so effective and has been around for a long time many new generation farmers may never have seen the diseases.

Farmers need to be confident that the disease risk will always be present and that a sound vaccination programme will be stopping the disease from happening. Most of the disease outbreaks are now associated with farmers forgetting to vaccinate.

The cost of a clostridial vaccination will depend on the risks on your farm, your farming system, and the level of protection you require. Your local VetEnt vet will be able to work through the options with you and develop a plan to suit your needs.

Management and Control.

Infected animals usually die soon after infection so prevention is the only choice.

Prevention is by vaccination programme.

There is a wide range of vaccines available which are used in a variety of vaccination programmes:

• Lambs after weaning.
• Breeding ewes & lambing hoggets.
• Pre-lamb ewe vaccination.
• Lambs at docking.