A new strain of porcine reproductive and respiratory virus (PRRS) has emerged on hog farms in Iowa and Minnesota, spreading rapidly in herds when it strikes.
Veterinarian Paul Yeske said strain 1-4-4 is the most dramatic PRRS he has ever seen.
“I think this one's the most dramatic as far as the number of aborts and the number of sow mortalities,” Yeske said in a webinar hosted by the Swine Health Information Center (SHIC) .
“We've seen anywhere from four to five weeks of production essentially aborted out and sow mortality is anywhere from 10 to 20 per cent of the sows dying off and very rapidly within a two- to three-week period of time.”
Piglet mortality has been extremely high, too, with numbers as high as 80 per cent, a number Yeske said he didn’t think was possible. But this strain is different.
The clinical signs that present most often with this PRRS strain are pigs going off feed, abortions, increased sow mortality, increased piglet mortality and increased mummies. Yeske said this strain tends to have a pretty high post-weaning mortality and slow growth in the finishing phase.
Yeske said he’s not sure that previous immunity really made a big impact.
He has seen breaks in herds that are vaccinated, breaks in herds that had previous virus exposure less than a year ago and breaks in herds that have used vaccination, previous virus exposure.
In the end, he said it doesn't really seem to change the outcome much between the various combinations or even in the negative herds.