Is blanket vaccination of the sow herd 4 times a year the best for controlling PRRS? If so, do I need to vaccinate the progeny?

Is blanket vaccination of the sow herd 4 times a year the best for controlling PRRS? If so, do I need to vaccinate the progeny?

Sow blanket vaccination 3-4 times a year is the best strategy to control PRRS, but we must remember that vaccine protection is not 100% as it varies depending on the strain present on the farm.

What can we expect from a PRRS live vaccine?

It is also important to keep in mind that vaccination will help reduce clinical signs among sows and will also reduce virus shedding, helping prevent viremia in newborn pigs.

Something else important to mention apart from vaccination?

But despite vaccination, the virus can continue to circulate if gilt management is not adequate or if management in farrowing rooms does not follow a strict “all in all out”.

• Replacement animals:

Gilt management has to achieve the target of introducing gilts into the herd that are already immune to PRRS but not shedding the virus.

• Management:

When talking about farrowing room management, moving piglets or sows backwards must be avoided as it could be the reason for the virus persisting there.

If sows have to be moved backwards (as is the case when they are used as nurse sows) we have to ensure that the sow’s udder lines are cleaned and disinfected before receiving a new litter as they can transmit the virus if the previous litter was viremic (Garrido‐Mantilla, et al. 2020).

And what about PRRS piglet vaccination?

Piglet vaccination is an option when problems are present in the post-weaning phase.

But for the vaccine administered to the offspring to be effective it is better to have a stabilized herd (producing non-viremic piglets or very few quantity) otherwise vaccine efficacy will be reduced.

Therefore very often we’ll find both strategies used together: sow and piglet vaccination.

Analyzing processing fluids (aggregate samples from groups of pigs) using PCR (polymerase chain reaction) technology to get a cycle threshold (Ct) value, can help us to know if virus is present among piglets.

The Ct value reflects the level of viremia. High numbers indicate less virus circulation. Ct values > 34 indicate very low virus presence, and we can expect a better response to piglet vaccination.

If you want to know more about the different vaccination programs for PRRSv and the best way to use them, visit our video blog: Controlling PRRS

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