Ask the Vet - Vaccination timing reminder

I am sometimes confused by how many times I should be vaccinating my ewes against pasteurella and clostridial diseases. Can you suggest how often to vaccinate and when best to do so?

In short you must ensure two things:

• For previously unvaccinated sheep or those with an unknown vaccination history, give two doses of a combined pasteurella/clostridial disease vaccine, such as Heptavac-P Plus, with an interval of 4-6 weeks between injections.

• To maintain adequate immunity, ewes will require an annual booster of the same vaccine. This is best done 4-6 weeks before lambing.

The vaccination process simulates a natural challenge in sheep without the risk associated with exposure to the actual disease-causing organisms. For previously non-vaccinated ewes to develop an active immunity two doses are normally required. The first “primes” or stimulates the immune system to respond to the disease challenge. However, it is the second dose which raises the immunity to a protective level.

The immunity provided by these two doses does not last for ever. It declines slowly with time and has to be boosted at regular intervals. With pasteurella and clostridial diseases, ewes require an annual booster of the same vaccine used initially.

The correct approach to adopt is two doses of Heptavac-P Plus 4-6 weeks apart in previously unvaccinated ewes or those with an unknown vaccination history, followed by an annual booster to maintain adequate immunity levels. Using the correct dose rate of 2ml per injection is important too.

Planning the timing of the annual booster so that it takes place 4-6 weeks before lambing can provide additional benefits to newborn lambs. Antibodies produced in response to the booster pass from ewe to newborn lamb in the colostrum, thereby transferring sufficient immunity for the first few weeks of life before they too can be vaccinated.