Is ivermectin an effective treatment for PRRS?

Iowa State researchers examine anti-parasitic in sow farms that broke with PRRSV 1-4-4 V1C.


Ann Hess, National Hog Farmer

Aug 03, 2022


After a recent trial demonstrated that ivermectin treatment inhibits porcine reproductive and respiratory syndrome virus infection in PAM-pCD163 cells in a dose dependent manner in early stages of infection, researchers at Iowa State University set out to see if a standardized dose would have the same impact in a natural infection model.


According to Chris Rademacher, clinical professor in veterinary diagnostic and production animal medicine and swine extension veterinarian at Iowa State University, the study aimed to compare the performance of pens of nursery pigs with different interventions tulathromycin (Draxxin), ivermectin and control after a sow farm PRRS outbreak.


"That was the primary objective looking at mortality removal rates and treatment rates. Secondarily, we wanted to take a subset of those pigs and measure PRRS viremia by doing quantitative PCR and infection rates during those treatments," Rademacher says.


The study took place at a site with two sow farms (approximately 4,000 each) that flowed together into a 9,000 head nursery. Both broke with PRRSV 1-4-4 V1C in early 2021.


Each room was only filled by one sow farm. Farm 1 was filled with five rooms and Farm 2 was filled with four rooms. Rooms were filled in one to two wean days, usually two to three days apart. The test included 360 pens.


"Most of the pigs went into general population (63%). They left some empty pens in the middle with pull pens (22%) and then 15% of those pens were left empty and all the small pigs were sorted down upon placement," Rademacher says...