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Prepare for Pasteurellosis

Sylvaine Lacrosse BVetMed MRCVS, Molecare Veterinary Services

Whilst it was a fantastic summer for holiday makers, it wasn’t so great for growing grass and lamb growth. This unfortunately means that a lot of lambs are not reaching target weights, are needed to be kept longer and housed in the winter when this may have previously not been needed. This will undoubtedly lead to overstocking this winter and stress for lambs and ewes, stimulating the spread of Pasteurellosis and other diseases.

What is Pasteurellosis?

Pasteurellosis is caused by a combination of infectious agents, the most important bacteria being Mannheimia haemolytica, Bibersteinia trehalosi and Pasteurella multocida. These can all routinely be found in the tonsils and throats of healthy sheep, however in times of stress, such as overstocking at housing, immunosuppression results in rapid bacterial multiplication invading the lungs and bloodstream.

Signs of Pasteurellosis:

-Fever (up to 42°C)


-Respiratory signs: nasal discharge, cough, increased respiratory rate and effort

-Congested mucous membranes

-Sudden death

-Multiple sheep affected

How do I prevent the disease?

Prevent stress! Agreed, it is much easier said than done, but here are some tips to prevent stress at housing:

-Minimise draughts

-Minimise stocking density

-Optimise feed and water trough space

-Appropriate worm/fluke/fly/lice control

-Minimise unnecessary/ineffective handling

Unfortunately, we all know what sheep are like and even in the most ideal conditions, they will find a way to get stressed! Which is why we think vaccination should be implemented properly.


There are very good Pasteurellosis vaccines available, usually combined with Clostridial protection. Some examples below:

Vaccine Clostridial Pasteurellosis Primary course Pasteurellosis Booster
Heptavac P Plus Yes: 7 in 1

Protection up to 12m

Yes 2 doses 4-6 weeks apart 2-3 weeks prior to expected seasonal oubreaks.
Ovivac P Plus Yes: 4 in 1

Protection up to 12m

Ovipast Plus No Yes

Administer boosters in ewes 4-6 weeks pre-lambing to ensure protective antibodies in the colostrum for protection of new born lambs.

The biggest mistake made is the assumption that the Pasteurellosis protection lasts the same amount of time as the Clostridial Protection!

Clostridial protection lasts up to 12 months whereas Pasteurellosis protection lasts only up to three months. We therefore encourage boosting for Pasteurellosis prior to expected times of stress.

If you are expecting to be overstocked with lambs this winter, boost lambs with a straight Pasteurellosis vaccine such as Ovipast P 3 weeks pre-housing.

I haven’t vaccinated and my sheep are dying! What do I do?

Investigate. Speak to your Vet! Whilst Pasteurellosis is one of the most common causes of sudden death in sheep, unless the sheep have been clinically examined, been post-mortemed and/or laboratory tested, the cause of death cannot be confirmed.

Treat. If Pasteurellosis is suspected, your vet will most likely implement either a targeted or blanket treatment of the group with antibiotics and anti-inflammatories.

Isolate sick sheep to prevent spread of infection.

Monitor for any of the aforementioned signs of the disease.

Pasteurellosis is a debilitating disease and an outbreak can cause multiple losses for a farmer including dead stock, poor growth rates and treatment costs. We therefore strongly encourage these two points regarding Pasteurellosis prevention are undertaken; reduce stress and manage vaccinations appropriately.

For more information, please phone 01392 872934.

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